Properties of Cuprammonium Rayon

Properties of Cuprammonium Rayon

Cuprammonium rayon is a regenerated cellulose fibre known especially for its fine filament structure and soft, silk-like handle. Like viscose rayon, it is made from cellulose, but the method of manufacture gives it certain distinctive characteristics, particularly in fineness, appearance, swelling behaviour, and dye absorption.

The following points summarise the important properties of cuprammonium rayon. Some numerical values and older technical descriptions should be verified from standard textile fibre references before academic citation.

1. Extreme Fineness of Filaments

One of the most important characteristics of cuprammonium rayon is the extreme fineness of its filaments. Filaments as fine as about 1.33 denier have been reported as being regularly produced, whereas viscose rayon has often been described in older textile literature as having a usual denier of around 2.5 denier.

This increased fineness is generally associated with the stretching or drawing applied to the filaments during spinning. Finer filaments give the fibre a softer feel and a more delicate drape.

Needs source verification: The specific denier values of 1.33 for cuprammonium rayon and 2.5 for viscose rayon should be checked against a standard textile fibre textbook or manufacturer data.

2. Soft and Silk-like Handle

Because of its fineness, cuprammonium rayon produces a soft, smooth, and silk-like handle. This makes it suitable for lightweight fabrics where softness, fluid drape, and a refined appearance are desired.

In fabric form, this property can be especially useful for dress materials, linings, saree-like drapable fabrics, scarves, and other products where a soft touch is valued.

3. Similarity to Cotton, but with Greater Swelling

Cuprammonium rayon is a regenerated cellulose fibre and therefore has many properties similar to cotton. However, it differs from cotton in some important structural aspects.

The average degree of polymerisation, often written as DP, is lower than that of cotton. Also, a larger portion of the fibre structure is occupied by amorphous regions. Because of this, cuprammonium rayon swells more readily than cotton.

Technical Note:
In textile science, degree of polymerisation refers to the average length of cellulose polymer chains. A lower DP generally indicates shorter cellulose chains. Amorphous regions are less ordered parts of the fibre structure, and these regions are usually more accessible to water, dyes, and chemicals.

As a result of greater swelling and higher accessibility, chemical reactions may take place faster in rayon than in cotton. This is important in wet processing, dyeing, finishing, and chemical treatment.

4. Behaviour on Burning and Exposure to Sunlight

Like viscose rayon, cuprammonium rayon burns rapidly. Older textile sources state that it chars at around 180°C. It is also reported to be degraded and weakened by exposure to sunlight in the presence of oxygen and moisture.

On ignition, cuprammonium rayon may leave behind ash containing traces of copper, due to the copper-based solvent system used in its manufacture.

Needs source verification: The charring temperature of 180°C and the statement regarding copper-containing ash should be checked from authoritative textile testing or fibre chemistry references.

5. Tensile Strength

The average tensile strength of cuprammonium rayon has been reported as approximately 1.7–2.3 in the dry state and 0.9–2.5 in the wet state.

These values appear to come from older fibre-property references. The unit is not mentioned in the original note and should therefore be verified before use in formal academic writing.

Needs source verification: Confirm the tensile strength values and their units. In textile references, fibre tenacity may be expressed in g/denier, cN/tex, or other units.

6. Elongation at Break

Cuprammonium rayon has been reported to show an elongation at break of about 10–17% in the dry state.

This means that the fibre can stretch to some extent before breaking. In practical fabric behaviour, elongation influences comfort, drape, crease recovery, and handling during processing.

Needs source verification: The stated elongation range should be verified from standard fibre-property tables.

7. Moisture Regain

At 70°F and 65% relative humidity, the moisture content of cuprammonium rayon is reported to be about 11%, similar to viscose rayon.

This relatively high moisture regain contributes to comfort in wear, because regenerated cellulose fibres can absorb moisture better than many synthetic fibres such as polyester or nylon.

Needs source verification: The 11% moisture content figure should be checked against standard textile fibre regain tables.

8. Dye Absorption

Cuprammonium rayon has good dye absorption. Its absorption power for direct dyes has been reported to be greater than that of viscose rayon, resulting in deeper shades under comparable dyeing conditions.

This behaviour can be related to the fibre’s accessible cellulose structure and swelling tendency. In practical dyeing, this may affect shade depth, dye uptake, and process control.

Needs source verification: The comparison of direct dye absorption between cuprammonium rayon and viscose rayon should be checked from dyeing or fibre chemistry references.

9. Microscopic Appearance

Under microscopic examination, cuprammonium rayon filaments appear uniform in longitudinal view. Their surfaces generally show no prominent markings.

In cross-section, the filaments are usually round and smooth, though they may occasionally appear slightly oval.

Practical Note:
Microscopic appearance is useful in fibre identification. Cotton shows natural twists or convolutions, while viscose rayon often shows striations. Cuprammonium rayon is generally smoother and more uniform in appearance.

Summary Table: Key Properties of Cuprammonium Rayon

Property	Description	Practical Significance
Fineness	Very fine filaments; older sources mention about 1.33 denier	Soft handle, smooth surface, good drape
Handle	Soft and silk-like	Useful for lightweight, elegant fabrics
Structure	Lower DP than cotton; more amorphous regions	Greater swelling and chemical accessibility
Burning behaviour	Burns rapidly like viscose rayon	Important for fibre identification and safety understanding
Strength	Moderate tensile strength; reported values need unit verification	Affects processing and fabric durability
Elongation	About 10–17% dry elongation reported	Influences flexibility and fabric behaviour
Moisture content	About 11% at 70°F and 65% RH reported	Contributes to comfort and absorbency
Dye absorption	Good absorption of direct dyes; deeper shades reported than viscose rayon	Relevant for dyeing depth and shade control
Microscopic appearance	Smooth longitudinal view; round or slightly oval cross-section	Useful for fibre identification

Conclusion

Cuprammonium rayon is valued mainly for its fine filament structure, soft silk-like handle, good moisture absorption, and attractive dyeing behaviour. Although it shares many properties with cotton and viscose rayon because all are cellulose-based fibres, its greater fineness and smoother microscopic appearance give it a distinctive character.

For students and textile professionals, cuprammonium rayon is a useful example of how manufacturing method, fibre structure, and end-use performance are closely connected. However, some numerical values commonly found in older notes should be verified from reliable textile references before being used in academic or technical documentation.

Suggested References / Sources to Check

The following references may be useful:

1. Textile Fibres: Their Physical, Microscopical and Chemical Properties — J. Merritt Matthews
2. Textile Fibers, Dyes, Finishes, and Processes — Howard L. Needles
3. Physical Properties of Textile Fibres — W. E. Morton and J. W. S. Hearle
4. Manufactured Fibre Technology — V. B. Gupta and V. K. Kothari
5. Identification of Textile Materials — The Textile Institute
6. Textile Science — E. P. G. Gohl and L. D. Vilensky
7. Handbook of Textile Fibres: Man-Made Fibres — J. Gordon Cook
8. BIS, ASTM, or Textile Institute standards on fibre identification and moisture regain
9. Manufacturer technical data sheets for cupro / cuprammonium rayon
10. Academic papers or technical notes on regenerated cellulose fibres and cupro fibre properties

Manufacturing Process of Cuprammonium Rayon

Cuprammonium Rayon


Like Viscose Rayon, cuprammonium rayon is also a regenerated cellulose fibre. Cotton linters are used as the source of cellulose for this rayon.

Ammonical copper oxide solution is also known as cuprammonium hydroxide solution. Cuprammonium hydroxide solution is a solvent for cellulose. When a solution of cellulose in cuprammonium hydroxide is diluted with water or treated with dilute sulphuric acid, the cellulose is regenerated or reprecipitated. By using a spinnerette, filaments of this regenerated cellulose can be produced.

Manufacture of Cuprammonium Rayon

The source of cellulose for this rayon is cotton linters, the purification of cotton linters is carried out in two stages:

a. Mechanical Treatment
b. Chemical Treatment

Mechanical Treatment

The cotton linters are transported in bales in highly compressed state and the object of the mechanical treatment is to loosen them and to remove mechanically admixed and loosly bound impurities such as dust sand, seed residues etc.

Chemical Tratment

The mechanically opened and purified cotton linters are boiled under pressure for several hours with dilute sod ash ( Na2Co3) solution (2%) to which a little amount of caustic soda may be added. The natural fatty matter present in the cotton is converted into soluble substance by the action of soda ash and thus removed from cotton linters.

Dissolution of Cellulose

In this, a solution of hydrated copper sulphate in 300-400 liters of water is introduced in a vessel at ordinary temperature with stirring. Some sugar is also added followed by caustic soda solution to form copper hydroxide.

Ground linters suspended in water are added to the above mixture to form copper cellulose.

The copper cellulose is filtered to remove the liquid, well ground and dissolved in a solution of ammonia in water.

Spinning Solution

By adding certain compounds to the cuprammonium cellulose solution, the solution is made more suitable for spinning. These compounds include glycerine, glucose, tartaric acid, citric acid, oxalic acid, can sugar etc.

Stretch Spinning

In the spinning process, the cuprammonium cellulose solution is discharged through nozzles ( spinnerette) into a solution of sulphuric acid in the form of relatively thick threads which are subsequently pulled( stretched ) to very fine filaments.

Properties of Viscose Rayon

Properties of Viscose Rayon

Moisture Absorption

It absorbs more moisture than cotton. Moisture Content of Coton is 6% at 70 deg F and 65% RH, and for Viscose Rayon it is 13% under the same conditions.

Tensile Strength

The Tensile Strength of the fibre is less when the fibre is wet than when dry. It is 1.5-2.4 gpd in the dry state and 0.7-1.2 gpd in the wet state. For high tenacity variety the values are 3-4.6 gpd and 1.9 to 3.0 gpd.

Elasticity

The elasticity of Viscose Rayon is less than 2-3%. This is very important in handling viscose yarns during weaving, stentering etc when sudden tensions are applied.

Elongation at Break

Ordinary Viscose rayon has 15-30% elongation at break, whule high tenacity rayon has only 9-17% elongation at break.

Density

The density of Viscose rayon is 1.53 g/cc. Rayon filaments are available in three densities: 1.5, 3.0 and 4.5

Action of Heat and Light

At 300 deg F or more, VR loses its strength and begins to decompose at 350-400 deg F. Prolonged exposure to sunlight also weakens the fibre due to moisture and ultraviolet light of the sunlight.

Chemical Properties

Viscose rayon consists of cellulose of lower DP than cotton cellulose. Also amorphous region of Viscose rayon is present to a greater extent, therefore, Viscose rayon reacts faster than cotton with chemicals. Acids like H2SO4 HCL breaks the cellulose to hydrocellulose. Oxidising agents like Na(OCl)2, Bleaching powder, K2Cr2O7, KMnO4- form oxycellulose. Cold acid solutions for a short time do not attack viscose rayon.

Action of Solvents

Textile solvents can be used on Viscose rayon without any deteriorating effect. Viscose rayon dissolves in cuprammonium hydroxide solution.

Effect of Iron

Contact with iron in the form of ferrous hydroxide weakens viscose rayon yarns. Therefore staining, marking or touching of rayon to iron or iron surface should be avoided.

Action of Microorganisms

Microorganisms ( moulds, mildew, fungus, bacteria) affect the colour, strength, dyeing properties and lustre of rayon. Clean and dry viscose rayon is rarely attacked by moulds and mildew.

Longitudinal View

The longitudinal view of these fibres show many striations running parallel to the long axis of the fibre. The cross section of viscose has striated periphery, having many sharp indentations, and cross sectional contours vary from circular and oval to ribbon-like forms.

Some Common Indian Fabrics

Here is a site which gives some details about the fabrics sold in Indian markets ( although the language is a bit colloquial)

Khadi Cotton
Bandani Cotton
Linen
Poplin
Vial Cotton
Teri Rubia
2x2 Rubia Cotton
Lizzy Bizzy Cotton:50% cotton 50% Polyster
Polyester
Bafta Cotton
Lining cotton
Floral cotton
Small Pleads cotton
Medium Pleads cotton
Cotton Silk
Khadi Silk
Bandani Silk
Raw Silk
Pure Silk
Crepe Silk
Polyester Silk
Satin Silk
Crepe Back Satin
Chikan kari
Chiffon:
Georgette
Artificial Silk Sari fabric
Silk Sari fabric
Sari Border
Curtain Fabric
Crepe
Net Fabric
Tissue
Wool

Manufacturing Process of Viscose Rayon

Viscose Rayon

It is a regenerated cellulosic fibre and cellulose is the raw material for producing this man made fibre.

The raw material is obtained from a special variety of wood called spruce.

Manufacturing Process

a. Purification of Cellulose:

The manufacture of viscose rayon starts with the purification of cellulose. Spruce trees are cut into timber. Their barks are removed and cut into pieces measuring 7/8" x 1/2" x 1/4". These pieces are treated with a solution of calcium bisulphite and cooked with steam under pressure for about 14 hours.
The cellulosic component of the wood is unaffected by this treatment, but the cementing material called lignin, which is present in the wood, is converted into its sulphonated compound which is soluble in water. This can be washed off, thereby purifying the remaining cellulose. This cellulose is treated with excess of water. After this it is treated with a bleaching agent (sod hypochlorite) and finally converted into paper boards or sheets. This is called wood pulp, which is normally purchased by the manufacturers of viscose rayon.

b. Conditioning of Wood Pulp:
The pulp sheets are cut by a guillotine to the required dimension and are kept in a special room. Air moves freely among the divisors by means of ventilatorys, the temperature is maintained at 30 deg celcius. In this way the desired moisture content can be had.

c. Steeping Process:
The conditioned wood pulp sheets are treated with caustic soda solution ( about 17.5%). It is called mercerising or steeping. The high DP cellulose (1000) is converted into soda cellulose. The sheets are allowed to soak (steep0 until they become dark brown in colour. This takes about 1-14 hours. The caustic soda solution is drained off and sheets are pressed to squeeze out excess caustic soda solution. 100 kg of sulphite pulp gives about 310 kg of soda cellulose.

4. Shredding or cutting process:
The wet, soft sheets of soda cellulose are passed through a shredding machine which cuts them into small bits. In 2-3 hours the sheets are broken into fine crumbs.

5. Ageing Process:
To obtain almost ideal solution of cellulose, the soda cellulose is stored in small galvanised drums for about 48 hours at 28 deg C. This process is called ageing process.The ageing process is essential. During This process, the DP od soda cellulose is decreased from 1000 to about 300 by oxygen present in the air, contained in the drum.

6. Churning Process or Xanthation:
After ageing, the crumbs of soda cellulose are transferred to rotating, air tight, hexagonal churners or mixers. Carbon disulphide ( 10% of the weight of the crumbs) is added to the mixer and churned together for 3 hours by rotating the mixers at a slow speed of 2 rev per minutes. Sodium cellulose xanthate is formed during this process and the colors of the product changes from white to reddish orange.

7. Mixing or dissolving Process:
The orange product i.e. sod.cell.xanthate is in the form of small balls. These fall into a mixer called dissover which is provided with a stirrer. A dilute solution of caustic soda is added, and the contents are stirred for 4-5 hours and at the same time, the dissovler is cooled. The sod.cell.xan. dissovles to give a clear brown thick liquor, similar to honey. This is called 'viscose' and it contains about 6.5% caustic soda and 7.5% cellulose.

8. Ripening Process:
This viscose solution requires to be ripened to give a solution having best spinning qualities. Ripening is carried by storing the viscose solution for 4-5 days at 10 to 18 deg. The viscosity of the solution first decreases and then rises to its original value. The ripened solutoin is filtered carefully and is now ready for spinning to produce viscose rayon filaments.

9. Spinning Process:

The viscose solution is forced through a spinnerette, having many fine holes ( 0.05-0.1mm) diameter. The spinnerette is submerged into a solution containing the following chemicals.
10% --> sulphuric acid, 18%- Sod sulphate, 1% - Zinc sulphate, 2% glucose, 69% water.

The spinning solution is kept at 40-45 deg celcius.

Sodium sulphate precipitates the dissoved sod. cell.xanthate. Sulphuric Acid converts xanthate into cellulose, carbon disulphide and sod. sulphate. the glucose is supposed to give softness and pliability to the filaments whereas zinc sulphate gives added strength.

The quality of viscose rayon filament formed depends upon:

1. The temperature of the spinning bath
2. The composition of the spinning bath.
3. The speed of coagulation
4. The period of immersion of the filament in the spinning bath.
5. The speed of spinning.
6. The stretch imparted to the filaments.

As a number of filaments emerge from the spinnerette, they are taken together to an eye at the surface of the spinning bath and then guided to two rollers from where they are wound on to a spindle.

Common Yarn Faults in Manmade Fibres

Common Yarn Faults in manmade fibres

1. Slubs:

Slub like thick faults seriously mar the appearance of fabrics made from manmade fibres. The following measures can be taken

A. In Blends with cotton

a. properly select the cotton component
b. ensure proper grinding of wirepoints at cards
c. regularly check the ringframe drafting system.

B. In 100% manmade fibres

a. Ensure adequate number of doublings
b. avoid too wide a roller setting and inadequate weighting on rollers.
c. Select correctly the fibres in regard to their compatibility in length.

2. Crackers

This defect is characterised by the cracking sound produced when the yarn is pulled. The sound is produced due to sudden rupture of fibres curled around the yarn.

- Crackers are caused mainly by the presence of very long fibres due to improper cutting of the two.

- They can also be caused due to high vairability in the elongation of the constituent fibres in the blend.

- Ensure wider roller setting in the back zone, adequate roller weighting and avoid too narrow a spacing between the aprons.

- It is helpful to have low roving twist and higher spinning tension through the use of heavier traveller.

3. Neps

This can also mar the appearance of a fabric

- In man made fibres longer and finer fibres tend to produce more neps.
- Other reasons of neps are
- Excessing beating of fibres in the blow room
- Loading of licker-in or cylinder at card
- Blunt wire points on various carding elements
- excessive lap weight

4. Fluffy Yarn

In general presence of short fibres and proneness to static accumulation tend to produce this defect.

The fault can be corrected by maintaining proper atmospheric conditions and reducing the fluff on roving.

5. Smoky Yarn

- The yarn containing synthetic fibres get smoky through long exposure of the running bobbin in a dirty atmosphere in the ring spinning system.

- Installation of smoke filters in H-plant can correct the problem

- Use of roving build can check this defect.

Tsudakoma ZAX- Settings for standard Denim

Tsudakoma-ZAX Loom Settings for 14.5 Oz/Sq yd OE/OE Denim (EPI x PPI = 64 x 37) count (6s x 7s)


Back Rest- 125 mm (vertical)
-16th mark ( horizontal)

Dropper Box- 100 mm (vertical)
- 50 mm (vertical)

Shedding Amount

1st Frame- 99 mm
2nd Frame-91mm
3rd Frame- 83 mm
4th Frame- 75 mm

Heald Frame Height:

1st Frame - 43 mm
2nd Frame-41mm
3rd Frame-39mm
4th Frame- 37mm

Shed Crossing Timing- 290 deg

Leno Crossing Timing- 290 deg ( LH Side), 0 deg ( RH side)

Temple- 15 rings- Medium Type

Sub Nozzle angle- 4 deg
Sub nozzle height- 3rd Mark
Machine Pulley- 220 mm
Motor Pulley- 113 mm for 760 rpm

iboard Settings

Tension- 280 kgf
Upper Limit- 560 kgf
Lower Limit- 0 kgf
Pick Density- 37 pick
Turns/Pick- 4
Arrvial setting - 240 deg
Filling insertion timing- 80 deg
No. of Sub groups- 5

Timing

Feeler H1- 200 deg to 290 deg
H2- 200 deg to 310 deg
Forward- 350 deg
Rev (others)- 180 deg/320 d eg
(Filling)- 290 deg
WBS- 240deg-300deg

SENSOR/TROUBLE
Dropper Setting: 10 th Volume
Sensor- on
Feeler-on
Timing

Pin: 50deg-200 deg
Main: 50deg-200deg
AUX Main: 60deg-100deg
80deg

Auxiliary Nozzle- 76 deg-176 deg
1st Pick- 86 deg

Sub Nozzle

64deg-170 deg
100deg-190deg
130deg-220deg
150deg-230deg
170deg-250deg

Stretch Nozzle- 200deg-300deg

STOP MARK Data

1. F Kick ( Filling) - 0 upto 7 steps
2. F Kick (Others)- 0 upto 7 steps
3. R Kick ( Filling)- 0 upto 7 steps
4. R Kick (Others) - 0 upto 7 steps
5. Kick Back Speed- 1. Low 2, Medium 3, High On
6. Kickback order- on 1

1. Rev to Forward
2. Forward to Rev

7. Down time- 5 min
8. Fell Control-8
9. Dia Comp-48
10. Let Off Avg-2
11. F-Gain-0
12. R.Gain- 0

13. Gain -1
1. Low
2. Medium
3. High

14. Rush Torque- 1200%
15. change Picks-2
16. Change timing- 30 deg
17. 1 pick insertion- On
18. Autolevelling- On

Critical Process Parameters- Denim Manufacturing

Critical Process Parameters- Denim Manufacturing

Warping:

Machine Speed m/min= 600+-50
Tension on individual thread ( cN) 90+-30
Warping breaks ( Avg/10000m/400 ends) < = 0.2

Dyeing-cum-Sizing

1. Machine Speed = 30+-2
2. Size Viscosity ( Flow seconds) = 6+-1
3. Size Add on ( %)= 6+-2
4. Breaking Force (gf) sized yarn = >=1100
5. Tenacity ( cN/tex) ( sized yarn) = >13
6. Elongation ( %) of sized yarn >= 4.5

Finishing

Quality	7 x 6	7 x 6	7 x 7	7 x 9	7 x 6
Width(cm)	151+-1	149+-1	151+-1	151+-1	151+-1
Shrinkage ( %)	15+-1	14.5+-1	15.5+-1	16+-1	14+-1
Skew ( %)	5-11	5-11	5-11	5-11	5-11

Finished Properties of some Common Denim Fabrics

Finished Properties of Common Denim Fabrics: Understanding Weight, Yarn Count, Construction and Fastness

Denim is one of the most widely used fabrics in garments, especially for jeans, jackets, skirts, children’s wear and casual apparel. Although denim is often identified by its appearance, shade and wash effect, the real performance of denim depends on measurable fabric properties such as weight, yarn count, ends per inch, picks per inch, rubbing fastness and laundering fastness.

The original note listed finished properties for three common denim fabrics with ideal weights of 14.5 oz/sq yd, 13.75 oz/sq yd and 12.5 oz/sq yd. These values are useful because denim is often commercially discussed by weight category, but weight alone does not tell the full story. A merchandiser, fabric buyer or production person must also understand the relation between yarn count, fabric construction and finished performance.

Table of Contents

• Why Finished Denim Properties Matter
• Comparative Finished Properties of Common Denim Fabrics
• Understanding Fabric Weight in Denim
• Role of Warp and Weft Count
• EPI and PPI: Fabric Construction
• Rubbing Fastness and Laundering Fastness
• Practical Notes for Merchandisers
• Common Mistakes in Reading Denim Specifications
• Conclusion

Why Finished Denim Properties Matter

In denim manufacturing, the fabric that comes out of weaving is not the same as the fabric finally used in garments. Denim passes through finishing operations such as singeing, desizing, washing, sanforizing, softening, skew correction and sometimes special chemical or mechanical treatments. These processes change the fabric’s handle, dimensions, shrinkage, shade appearance and apparent fabric weight.

Therefore, when we say that a denim fabric is 14.5 oz, 13.75 oz or 12.5 oz, we should be clear whether we are talking about greige weight, finished weight or washed weight. Finished properties are especially important because the garment buyer and consumer experience the fabric after finishing, not at the loom stage.

Visual 1: Denim fabric properties map showing how weight, count, construction and fastness affect final performance.

Comparative Finished Properties of Common Denim Fabrics

Property	Heavy Denim	Medium-Heavy Denim	Medium Denim
Ideal Weight	14.5 oz/sq yd	13.75 oz/sq yd	12.5 oz/sq yd
Warp Count, Washed	6.9 ± 0.6	6.9 ± 0.5	6.9 ± 0.5
Weft Count, Washed	6.0 ± 0.4	6.9 ± 0.5	9.0 ± 0.5
EPI, Unwashed	70 ± 2	70 ± 2	70 ± 2
PPI, Unwashed	43 ± 2	43 ± 2	43 ± 2
Actual Weight	14.2 oz/sq yd	13.4 oz/sq yd	12.2 oz/sq yd
Rubbing Fastness, Dry	2–3	2–3	2–3
Fastness to Laundering	2	2	2

This small table contains an important technical lesson. The three fabrics have almost the same warp count, EPI and PPI, but the weft count changes. This means that the weight difference is mainly controlled through the weft yarn, while the face character of the fabric is kept broadly similar.

Understanding Fabric Weight in Denim

Fabric weight in denim is commonly expressed in ounces per square yard. Heavier denim generally feels thicker, stronger and more rigid, while lighter denim feels softer, more flexible and easier to wear in warm conditions. A 14.5 oz denim is usually perceived as a heavy and rugged fabric, while a 12.5 oz denim is closer to a medium-weight commercial denim.

Denim Weight	Practical Meaning	Typical Use
Around 14.5 oz	Heavy denim	Rugged jeans, workwear-inspired garments, structured bottoms
Around 13.75 oz	Medium-heavy denim	Regular jeans, casual bottoms, durable apparel
Around 12.5 oz	Medium denim	Comfortable jeans, fashion denim, lighter casual wear

In the data, the actual finished weights are slightly lower than the ideal weights. For example, the 14.5 oz fabric shows an actual weight of 14.2 oz/sq yd, while the 12.5 oz fabric shows 12.2 oz/sq yd. Such differences can occur because of yarn variation, weaving tension, finishing loss, moisture content and process conditions.

Role of Warp and Weft Count

The warp yarn count remains nearly the same in all three fabrics, around 6.9 Ne. This suggests that the main difference between the three denim qualities is not coming from the warp yarn, but from the weft yarn. The weft count changes from 6.0 Ne in the heavier fabric to 9.0 Ne in the lighter fabric.

In the English cotton count system, a lower count number means a coarser yarn. Therefore, 6s weft is coarser than 9s weft. This explains the weight difference clearly:

\( \text{Coarser weft yarn} \Rightarrow \text{more yarn mass per unit area} \Rightarrow \text{heavier denim} \)

\( \text{Finer weft yarn} \Rightarrow \text{less yarn mass per unit area} \Rightarrow \text{lighter denim} \)

This is a useful point for merchandisers. If EPI and PPI remain almost constant, but fabric weight changes, the change is often due to yarn count, especially weft count.

Visual 2: Relationship between weft count and denim weight, showing why coarser weft gives heavier fabric.

EPI and PPI: Fabric Construction

The construction shown in all three fabrics is approximately 70 × 43. This means that the fabric has about 70 ends per inch in the warp direction and about 43 picks per inch in the weft direction. Since EPI and PPI are the same across all three fabrics, the construction density remains largely unchanged.

EPI stands for ends per inch, or the number of warp yarns in one inch of fabric width. PPI stands for picks per inch, or the number of weft yarns in one inch of fabric length. In the given case:

\( \text{EPI} = 70 \pm 2 \)

\( \text{PPI} = 43 \pm 2 \)

This is a good example of how fabric properties should be read together. Looking only at fabric weight may not explain the reason for the difference. Looking at weight, yarn count and construction together gives a much clearer technical understanding.

Why Warp Count is Similar but Weft Count Changes

In conventional denim, the warp yarn is usually indigo dyed, while the weft yarn is generally undyed or lightly coloured. The warp gives denim its characteristic blue appearance, while the weft contributes strongly to weight, handle and body.

Keeping the warp count similar helps maintain a consistent denim appearance and surface character. Changing the weft count allows the manufacturer to create different weights without drastically changing the face appearance of the fabric. This is why three fabrics can look similar at first glance but behave differently in hand feel, stiffness and garment comfort.

Rubbing Fastness and Laundering Fastness

The dry rubbing fastness given for all three fabrics is 2–3. This indicates that colour transfer during rubbing is a concern. In denim, this is especially important because indigo dye is mainly present on the surface of the yarn rather than deeply penetrating the fibre.

A dry rubbing fastness rating of 2–3 means that some colour transfer may occur when the fabric rubs against another surface. This may appear as blue staining on light-coloured shirts, shoes, bags, upholstery or inner pocketing. For the merchandiser, this means care instructions and buyer expectations should be handled carefully.

The laundering fastness is shown as 2 for all three fabrics. This means that the fabric is likely to lose shade during washing. In denim, this is not always considered a defect because fading is often part of the desired denim character. However, from a quality-control perspective, this rating must be interpreted according to the buyer’s requirement.

Visual 3: Denim fastness performance map showing rubbing fastness, laundering fastness and consumer risk points.

Relationship Between Weight, Comfort and Durability

Heavier denim usually gives better body and ruggedness, but it may feel stiff and warm. Lighter denim gives better comfort and flexibility, but may not have the same rugged appeal. Medium-weight denim often becomes the commercial balance between durability and wearability.

Fabric Weight	Advantages	Possible Limitations
Heavy denim	Strong body, rugged look, durable feel	Stiffer, warmer, slower to break in
Medium-heavy denim	Good balance of strength and comfort	May still feel firm before washing
Medium denim	Softer, easier to wear, better drape	Less rugged appearance than heavy denim

Simple Weight Calculation Concept

A simplified fabric weight relationship can be understood as:

\( \text{Fabric Weight} \propto \text{Yarn Linear Density} \times \text{Fabric Density} \)

In practical terms:

\( \text{Weight} \approx f(\text{Warp Count}, \text{Weft Count}, \text{EPI}, \text{PPI}, \text{Crimp}, \text{Finishing}) \)

This means that the final denim weight is influenced by both yarn size and construction. In the present example, because EPI and PPI are constant, the difference in weight is largely explained by the difference in weft count.

Practical Notes for Merchandisers

A merchandiser should not approve denim only by looking at the weight. Two denim fabrics with the same weight can behave differently if the yarn count, twist, fibre quality, weave compactness, finishing route or shrinkage control is different.

Checkpoint	Why It Matters
Finished weight	Determines body, feel and product category
Warp and weft count	Explains yarn thickness and fabric mass
EPI and PPI	Indicates fabric density and construction stability
Rubbing fastness	Shows risk of colour transfer
Laundering fastness	Shows expected wash-down behaviour
Shrinkage	Critical for garment fit
Skew and bow	Important for leg twisting in jeans
Handle and stiffness	Affects consumer comfort
Shade consistency	Critical for bulk approval

Common Mistakes in Reading Denim Specifications

One common mistake is to assume that heavier denim is always better. This is not true. Heavy denim may be unsuitable for hot climates, fashion silhouettes or comfort products. Another mistake is to compare denim fabrics only by ounce weight without checking construction.

A third mistake is ignoring rubbing fastness. Denim may pass visual inspection but still create complaints if it stains other garments or accessories. Similarly, laundering fastness must be understood according to the intended wash effect. In denim, fading can be either a defect or a design feature, depending on the product brief.

Buyer’s Interpretation of the Given Data

The data suggests that the three denim fabrics are constructed with a similar warp system and similar fabric density. The main adjustment is in the weft yarn count, which changes the fabric weight. The heaviest fabric uses the coarsest weft yarn, while the lightest fabric uses the finest weft yarn.

The fastness ratings are similar across all three fabrics, which means that changing the weight has not significantly improved or reduced rubbing and laundering fastness. This is important because fastness depends more on dyeing, washing and finishing conditions than on weight alone.

Knowledge Nugget

In denim, the blue character comes mainly from the warp, but the body of the fabric is strongly influenced by the weft. Therefore, two denim qualities can have a similar face appearance but different weight and handle because of the weft yarn.

Conclusion

The original table is small, but it contains a useful technical lesson. Denim weight is not an isolated property. It is connected with yarn count, fabric construction and finishing. In the given examples, all three fabrics have nearly the same EPI, PPI and warp count, while the weft count changes. This change in weft count explains the difference between heavier and lighter denim fabrics.

For a merchandiser, this type of specification is very valuable. It helps in understanding why a fabric feels heavier, why one denim quality may feel more rigid, and why fastness ratings must be checked even when the construction looks acceptable. A good denim evaluation should always combine measurable data with hand feel, shade behaviour, washing performance and final garment requirement.

Related Reading on Denim, Fabric Construction and Finishing

• Some Notes on Denim Washing
• Critical Process Parameters- Denim Manufacturing
• Manufacturing Process of Denim
• How to calculate the weight of Fabric
• Count, Construction and Width of common Cotton Fabrics

General Disclaimer

This article is intended for educational and practical understanding of textile and denim concepts. Actual fabric properties may vary depending on fibre quality, yarn type, spinning method, weaving conditions, dyeing process, finishing route, testing method and buyer specification. Readers should verify production decisions with mill technologists, testing laboratories, buyer standards and applicable textile testing methods before applying these values commercially.

Controlling Shade in Indigo Dyeing of Denim

If shade is getting:

Redder- Increase the conc. of Caustic , slightly decrease the conc. of Hydro
Redder, Duller- Increase the con. of hydro
Greener, Paler- decrease the con. of hydro
Greener, duller- Increase the con. of caustic
Bronzing- Increasing the con. of Hydro

Denim of Polyester Cotton Blend

In such denims, the polyester used in warp is kept low about 20-25%, because the blend is harder to dye than cotton . Polyester can be used in much higher percentage in filling. It has the advantage of being strong, durable and even in appearance.

Blending at draw frame

Blending at Draw Frame

This method is normally used for binary blends only. The required blend proportion is adjusted by the number of slivers of each component and the hank of respective slivers.

The fleece blending is done on the blending Drawframes specifically designed for this purpose. They are fed with 16-20 slivers at the back and therefore provide a much greater flexibility as regards the blend ratios.

Advantage

- Easier to obtain uniform blend ratio.
- During opening and carding, optimum settings fro each blend component can be used for better quality of output with less damage to the fibres. 

- Easy working.

Disadvantages

- Difficult to attain random arrangement of fibres in the yarn cross section.
- Additional drawing capacity needed.
- Separate opening lines needed for each component.

Blending of Combed Cotton Sliver and Polyester

Many Indian mills resort to this practice when the humidity control or conditions of machines is very poor.

Advantages
- Produces very intimate blend
- Trouble free running and high productivity at card.
- Less yarn imperfections due to better fibre individualisation because of reprocessing of the cotton component.
- Reduced number of d/f passages.
- Lower end breaks due to fewer slubs.
-better uniformity of dyeing due to more intimate blend.

Disadvantage
- Poor tenacity and evenness in blend yarn.
- High cotton nep content in blend due to reprocessing
- Need of additional b/r and card capacity
- Slightly higher waste in b/r and carding.

Optimum Blending Method of various Blends

1. For blends like P/V , blowroom blending is effective as they need similar b/r sequence.
2. For blending of manmade stack blending method is generally used.
3. The polyester /cotton or acrylic/cotton are generally blended at d/f because cotton component needs a severe opening and cleaning action
4. Where there is a problem of running 100% polyester on card, stack blending of polyester stock and combed cotton may be resorted to.
5. In case of v/c blend, they should be blended at the draw/frame as they need quite a different opening sequence.  

Blending at Blowroom

Blending at Blowroom: Methods, Advantages and Limitations

In cotton spinning, blending is one of the most important operations carried out at the blowroom stage. The purpose of blending is to mix different fibre components in the required proportion so that the final yarn has consistent quality, appearance, strength, and performance.

Blending may be required for several reasons: to mix cottons of different varieties, to combine natural and man-made fibres, to use recovered fibre waste in a controlled manner, or to maintain uniformity when fibres come from different bales or lots.

At the blowroom, blending is generally carried out by three main methods:

1. Feeder blending
2. Stack blending
3. Lap blending

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1. Feeder Blending

In feeder blending, different fibre components are fed into different hopper feeders. The feed from each hopper is adjusted according to the required blend ratio.

For example, if a blend of cotton and polyester is required, cotton may be fed through one hopper feeder and polyester through another. The delivery from each feeder is adjusted so that the desired percentage of each fibre is obtained in the final blend.

The amount of material taken from each bale for feeding these blenders should generally not exceed 2–3 kg. Taking small quantities from many bales helps in achieving better mixing and reduces variation between bales.

This method is generally employed when more than two components are required to be blended.

Practical Note:
Feeder blending is useful when the mill wants flexibility in changing blend ratios. However, the accuracy of the blend depends greatly on the correct setting and regular monitoring of the feeders.

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2. Stack Blending

In stack blending, the blend components from the bale or from bale breakers are first weighed. These pre-opened fibre components are then laid down in alternate layers to form a stack.

The stack is usually laid horizontally. During feeding, the material is withdrawn vertically. This vertical withdrawal helps in taking fibre from several layers at the same time, which improves mixing.

For example, if cotton, polyester, and recovered fibre are to be blended, they may be laid layer by layer in the required proportion. When the stack is cut or withdrawn vertically, material from all layers is taken together, producing a more mixed feed.

Technical Note:
Stack blending depends heavily on accurate weighing and careful layer formation. If the layers are not uniform, the final blend may show variation.

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Advantages of Feeder and Stack Blending

Both feeder blending and stack blending are widely used because they can provide a reasonably intimate and homogeneous blend when properly controlled.

• More intimate and homogeneous blending can be achieved.
• Only one opening line is generally needed.
• They provide simple control over the use of recovered fibre waste.
• They require minimum man-hours for blending when properly organized.

Disadvantages of Feeder and Stack Blending

However, these methods also have some limitations. The blend quality depends on the accuracy of feeding, weighing, and operator control.

• It may be difficult to attain a perfectly uniform blend ratio.
• They demand greater skill on the part of the operator.
• They can be labour-intensive and somewhat slow, especially in manual systems.

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3. Lap Blending

In lap blending, laps of the component fibres are prepared separately, usually at the breaker scutcher. Generally, three to four laps are produced and then fed together to the finisher scutcher in the desired ratio.

Each lap represents a particular fibre component or blend component. By feeding these laps together, a more controlled blend can be obtained. Since the lap weights can be measured and controlled, lap blending provides better control over the blend ratio.

This method was more common in older blowroom lines where scutchers and lap-forming machines were used. In modern blowroom systems, chute feed systems have largely replaced lap-forming systems, but the principle remains important for understanding traditional blowroom blending.

Advantages of Lap Blending

• It ensures good blend homogeneity.
• It is easy to work once the system is properly set.
• It provides good control over the use of recovered fibre waste.
• A uniform blend ratio can be achieved.

Disadvantages of Lap Blending

• The opening line has to be modified to provide both breaker and finisher scutchers.
• Proper control over lap weights is essential.
• Additional machinery and handling may be required.
• If lap weights vary, the blend ratio may also vary.

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Comparison of Blending Methods at Blowroom

Method	Basic Principle	Main Advantage	Main Limitation
Feeder Blending	Different fibres are fed through separate hopper feeders in the required ratio.	Useful for blending more than two components.	Uniformity depends on feeder setting and control.
Stack Blending	Fibres are weighed, laid in alternate layers, and withdrawn vertically.	Simple and suitable for pre-opened fibres.	Requires careful weighing and skilled handling.
Lap Blending	Laps of different fibre components are fed together to the finisher scutcher.	Provides better control over blend ratio.	Requires control of lap weights and suitable machinery.

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Importance of Proper Blending

Proper blending at the blowroom stage has a direct effect on the quality of yarn. If the blending is poor, the yarn may show variation in strength, colour, dye uptake, evenness, and appearance.

In blended yarns such as polyester-cotton, viscose-cotton, or cotton mixed with recovered fibre, improper blending may lead to streakiness, shade variation after dyeing, and inconsistent performance during spinning.

Therefore, the blowroom blending method must be selected according to the type of fibres, number of components, required blend accuracy, machinery available, and the quality level expected in the final yarn.

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Conclusion

Blending at the blowroom is not merely a mechanical mixing operation. It is a quality-control operation that determines the uniformity of the material right from the beginning of the spinning process.

Feeder blending and stack blending are simpler methods and are suitable where flexibility and basic control are required. Lap blending, on the other hand, offers better control over blend ratio but needs proper machinery and careful control of lap weights.

A good blowroom blending system should achieve three things: the correct blend ratio, uniform distribution of fibres, and minimum variation from bale to bale and batch to batch.

Blending-2

How to select Blend Constituents


Selection of Blend Constituents depends upon the following factors:

1. Type of Fibre
- Depending upon the end use of the fabric, blend constituents are chosen.

- For example, it is well known hat a polyester-cotton yarn looks fuller as compared to the lean look of polyester-viscose yarn.

- Therefore for light constructions like shirtings, polyester-cotton blend is used.

- However polyester-viscose blend is preferred for medium and heavy construcitons such as suitings.

2. Compatibility of blend fibres

Compatibility must be there in terms of the following properties:

a. Length and Denier of Fibres:

- As a general rule, these two fibre properties should be nearly the same for all the constituents.
- For example in a viscose rayon cotton blend, the rayon staple of 1.5 denier and 29-32 mm length is generally used since the cotton component used has a denier of around 1.5 and a length of 28mm.

b. Extensibility

- A large difference in the breaking elongation of the fibres in a blend adversly affects the yarn tenacity.

c. Density
- The blend fibres should prefereably have the same density. Any large differences on this account will lead to selctive separation while conveying the blended stock through ducts under the influence of air suction in the blow rooms.

d. Dispersion Properties
- This property describes the ability of an individual fibre to separate from its group and disperse thoroughly within the fibre matrix of the blend to produce an intimate and homogeneous blend.

e. Drafting Properties
- Some fibres like viscose are outstanding it terms of draftability. These fibres, when blended with other fibres act as good carriers to obviate the trouble relating to drafting.

f. Dyeing Properties
- In case the blend yarn or fabric is to be dyed subsequently, due consideration should be given to the dyeing properties of individual fibre components.

CHARACTERISTICS DESIRED IN A BLEND YARN

A. The constituent fibres should be arranged at random in the yarn cross section.

B. The ratio between the blended fibres should be uniform at any cross section of the yarn.

C. There should not be any long-term or short-term irregularity in blend ratio of blended fibres.

Blending-1

Blending-1

Neither natural or manmade fibres are optimally suited to certain fields of use, but a blend of these two fibres types can give the required characteristics.

Objectives:

1. Improvement in Functional Properties

A 100% single fibre yarn cannot impart all the desired properties to a fabric.

For example 100% viscose rayon suffer from low tensile strength, poor crease resistance and low abrasion resistance.

Similarly 100% polyester fabrics are not desirable as they are prone to static accumulation, hole melting and pilling. They are moisture resistant, difficult and expensive to dye and have a poor hand.

These negative attributes of polyester and viscose can be reasonably neutralised by addition of a certain percentage of each fibre.

2. Improved Process performance

Some fibres like polyester at times are quite troublesome to work in 100% form especially at cards. Addition of fibres like cotton or viscose rayon in the previous process has been seen to facilitate the smooth carding of such fibres.

The blending of manmades which are longer and finer to cotton which is shorter influences the spinnablility as well as productivity.

3. Economy

The price of manmades is much more stable than that of natural fibres like cotton. Price stability can enable the mills to pursue optimisation of their fibre purchase programme.

Blending could also be used for reducing the mixing cost. For example, a fibre like viscose can be blended with cotton for producing specific yarns with reduced raw material costs.

4. Fancy Effect

Fibres with a variety of colour mixture or shades can be produced by blending different dyed fibres at the blowroom, drawframe or roving stage.

5. Aesthetics

The aesthetics of a fabric can be developed by selecting specific blend components and their properties.

Receipes for different shades of Denim

Receipes For Different Shades on Denim


A) Black-on-Black
Black-on-Blue

Recipe

Liquid Sulphast Black= 200 gpl
Sodium Sulphide= 20 gpl
Sandozol HSI = 10 gpl
Soda Ash= 10 gpl

B) Blue-on- Blue

Receipe

Liquid Sulphar Navy Blue = 100 gpl
Liquid Sulphast Black= 50 gpl
Sodium Sulphide= 20 gpl
Sandozol HSI= 10 gpl
Soda Ash= 10 gpl

C) Reactive Series

Receipe

01) Ramazol Turquoise Blue G = 110 gpl
Urea= 100 gpl
Swanic 6L= 10 gpl

02) Sodium Silicate= 250 gpl
Caustic Soda = 10 gpl

Ratio of 01) and 02) = 3:1

D) Ramazol Coffee Brown G

Receipe
01) Coffee Brown G = 100gpl
Urea = 100 gpl
Swanic 6L= 10 gpl

02) Sodium Silicate = 250 gpl
Caustic Soda= 10 gpl

Ratio of 01) and 02) = 3:1

E) Ramazol Parrot Green

Receipe
01) Ramazol Turquoise Blue G = 90 gpl
Ramazol Yellow FG = 40 gpl
Urea= 100 gpl
Swanic 6L= 10 gpl

02) Sodium Silicate = 250 gpl
Caustic Soda = 10 gpl

Ratio of 01) and 02) = 3:1

F) Ramazol Blue

Receipe
01) Ramazol Black B = 70 gpl
Urea = 100 gpl
Swanic 6L = 10 gpl

02) Sodium Silicate = 250 gpl
Caustic Soda = 10 gpl

Ratio of 01) and 02) = 3:1

Sewing Problems

Sewing Problems

1. Problems of stitch formation

It gives rise to poor seam appearance and performance

These are

- Slipped stitches
- Staggered stitching
- Unbalanced stitches
- Variable stitch density
- Puckering
- Needle, bobbin or loops thread breakage

a. Slipped Stitches

Arise from the hook or loopes in the machines not picking up the loop in the needle thread.

b. Staggered Stitches

Can be caused by yarns in the fabric deflecting the needle away from a straight line of stitching, giving a poor appearance.

c. Unbalanced stitches

It can reduce the potential of stretch in a seam in a knitted fabric and may lead to seam cracking.

d. Variable stitch density

It arises from insufficient foot pressure in a drop feed system, causing uneven feeding of the fabric through the machine.

PROBLEMS OF PUCKER

Pucker is a wrinkled appearance along a seam in an otherwise smooth fabric. It generally appears as if there is too much fabric and not enough thread in the seam.

Causes of Pucker

a. Seam pucker due to differential fabric stretch

Remember that the upper fabric would tend to move forward by an amount always less than the movement of lower one. This is due to the fact that the lower layer is positively gripped by the feed dog and upper layer is driven by the friction by the lower layer.

b. Differential pucker caused by fabric dimensional instability

The essential feature causing differential pucker is the relative change in dimensions of upper and lower fabric after the seam has been made.

Differential pucker due to dimensional instability may be suspected when the two fabrics being joined are markedly different or when one shows noticeably more pucker than the other.

c. Seam pucker due to extension in the sewing threads.

All sewing threads have some extensiblity and they are extended by the action of the tension devices and pass into seam in an extended state. When removed from the machine they will tend to contract.

When thread extension is proved to be the cause of puckered seam, consideration must be given to the type of thread being used and to the tensiton settings on individual machines.

d. Seam pucker due to sewing thread shrinkage

Cotton sewing threads increase in diameter and shrink in length when wet and these distortions may cause pucker in sensitive fabrics. Synthetic sewing threads have negligible wet shrinkage and should always be used for such fabrics.

e. Seam pucker due to structural jamming

The presence of the seam itself may introduce a distortion. It is in no way dependent on the action of the sewing machine, but it invariably appears as soon as the seam is formed.

As soon as a woven fabric has been constructed so as to be close to the practical weaving limit, that is very less space left between the yarsn either warp or weft ways, it may be extremely difficult to force in any more threads in either direction.

The term 'structural jamming' is given to this type of pucker because it results directly from the act of jamming extra threads into a structure which is already too closely set to accommodate them.

Seam pucker due to mismatched patterns

This is due to the discrepency between the lengths of the stitching lines on the pattern pieces that go together in the seam. Thus there is a difference in the lengths of the cut parts which the machinist is sewing together.

Problems of damage to the fabric along the stitch line

a) Mechanical damage

1. Needles can strike and break fabric yarns and burst the loops in knitted fabrics. For this appropriate set and ball point needles are necessary.

2. Needles should always be as small as possible.

3. Sometimes the combination of the machine speed and nature of the fabric prevents the yarns from moving out of the way of the needle sufficiently fast to avoid damage .To solve the problems either reduce the speed - which means lesser production or ensure that the fabric is adequately lubricated. It calls for having resin finish on the fabric.

- All sample lengths of the fabric should be tested for sewability and the necessary finishes should be specified before the bulk fabric is ordered and bulk fabric should be tested before production to ensure that finishing treatment has been effective.

b) Needle Heating Damage


Needles heating occurs as a result of friction between the needle and the fabric being sewn.

In high speed sewing of dense material, temperatures as high as 300 deg or even 350 deg can be reached.

At this temperature it is possible that the needle may suffer damage and lose its hardness.

Natural fibres in a fabric or thread can withstand these temperatures for a short time.

With synthetic fibres, the position is more critical since the fibres melt at around 100 deg C, polyamide and polyester soften at about 230 deg C and polyacrylics will only withstand temperatures upto 280 deg C.

Overheated needes can
- Soften the synthetic fibres
- Weaken them
- Produce rough seam with
- harsh stitch holes

Melted fibres stick to the surface of the needes
- Increase its friction
- cog the eye and the groove
- No sew
- Skipped stitches

Reduction of Friction
- Reduce the sewing speed
- Changing the shape or surface of the neede
- long seams will ensure more heat build up in the needle
- Jet of compressed air.
- User spun or corespun yarns.

Sewing-9

Thread Sizing

1. Metric Ticket Number system

eg if Nm 60/1 means 60m of it would weigh 1 gm.

of 120/2 means 120 m of it would weigh2 gms. In this case it would have a resultant count of 60 ( i.e. 60 gms) would weigh 1 m.

The metric ticket number of this thread based on a three fold equivalent is then three times that i.e.

Nm 80/2= Ticket Number 120
Nm 30/3 = Ticket Number 30 and so on..

2. Cotton Sewing threads are sized on the cotton ticket number system

eg. 3/60 Ne --> equivalent cT= 20--> Three fold equivalent = 60 ( Ticket Number)

3. Denier system--> Weight in gms of 9000 m of length

Thread Packages

1. Spool

a. Used for domestic sewing
b. Not suitable for delivering thread to high speed industrial machines.

2. Cops

a. Small cylinderical flangeless tubes onto which thread is cross bound for stability.
b. Lack of flanges facilitates regular offwinding from the top on sewing machines.
c. Their small diameter makes them less suited for the faster thread offtake of machines.

3. Cones

a. They contain 5000 m cross wound for stability and good offwinding performance.
b. They give troublefree thread delivery.
c. Ideal in situations where thread consumption is high.

4. Vicone- Contain any spillage

5. Large Package

a. Can hold in excess of 20000 m of spun or corespun thread

6. Container

cocoons: They are self supporting ie. centerless, thread packages.

Sewing-8

Thread Finish


The final aspect of thread construction to be studied is that of surface finish.

The most important finish is lubrication.

The requirement of a lubricating finish applied to a sewing thread is that it should produce a regular level of friction, and that for synthetic threads in particular, it should provide protection from needle heat.

Without a controlled amount of lubrication applied to threads, unacceptable damage would be inflicted on them during the sewing process which would result in thread breaks during sewing and seam breakdown in wear.

A lubricant


- Must not clog the needle eye
- should not stain
- Must allow thread to unwind evenly from the package
- Must reduce friction with m/c surfaces but without creating too much slippage
- Must not react adversly to high temperature
- Must be inexpensive
- Easy to apply to the thread during manufacturing.

Other finishes


- Mildew or rot resistant finish
- Water resistant finish
- Soil Release
- Flammability finish

Terry Towel Manufacturing Process

In addition to what I have mentioned earlier, Terry Towelling is excellently described in this blog.
Replete with pictures, this post replies succintly the various process steps in manufacturing terry towel.

Sewing-7

Sewing Threads

Threads can be

Spun


Threads made from spun yarn have good sewing performance, good dimensional stability and good stitch locking properties in the seam due to their fibrous surface.

Monofilament


One filament of large size. It is harsh on machine and rather inflexible because the cross sectional shape never varies as it would with multifilaments.

Its cut ends are harsh on the wearer. It has virtually no seam grip and stitches tend to unravel easily.

Its good advantage is a translucency which reduces the need for shade matching.

Multifilament Form


Their fineness enables larger thread packages to be used, thus saving operator time changing them.

Corespun


In this a continuous multifilament core is wrapped around a sheath of spun fiber, two or three of these yarns are then plied together.

The majority of these corespun threads consist of a polyester core and a cotton cover.

Sewing-6

Sewing Threads

Selection of sewing threads depends upon the following factors:

1. Performance properties during sewing
2. Performance in the completed garment under conditions of wear and cleaning

Appearance and perfomance of the threads depends upon:

1. Fiber Type
2. Construction
3. Finish

1. Fiber Type

a. Linen- Useful in making strong, rather stiff threads for heavy sweing and also for button sewing.

b. Slk - Advantage- Good appearance and performance, Disadvantage- High Cost

c. Cotton - Good Sewing Performance, Disadvantages- Strength and abrasion resistance are inferior to synthetic threads of equal thickness.
It is more stable at higher, dry temperature than synthetics- less affected by hot needles during sewing.

d. Viscose- 1. Do not have the strength or durability of synthetic fibres. 2. Low tenacity and low strength when wet. 3. High lustre- can be used for embroidery.

Nylon/ Polyester Threads
1. Not affected by rot, mildew or bectaria
2. High Tenacity
3. High resistance to abrasion
4. Good resistance to Chemicals

2. Construction

When the fibres occur in short lengths, they must be twisted together, initially into a single yarn, and then that twist must be balanced by applying a reverse twist, as two or three such yarns are combined to form the thread construction.

- Twist in singles yarn consolidates the strenth and flexibility provided by the fibres themselves.

- Without the reverse twist, known as finishing twist, a conventional thread cannot be controlled during sewing. The individual plies would separate during their repeated passages through the needles and over the sewing machine control surface.

- Remember that the frictional forces acting on a thread during its passage through a sewing machine also tend to insert some twist, predominantly in one direction.

Sewing-5

Needle Point

These are divided into two parts- Cutting points and cloth points.

Cutting Points: These are needed for fabrics like leather where there are no gaps in the structure.

Cloth Points: These are needed for those fabrics where there are gaps in the structure.

Cutting point Neeedles

a. Wedge Point: It produces most durable seam on leather. It resists great stress, the incision lie at right angle to the seam direction and high stitch density can be achieved.

b. Cross Point: Here strength is considerably weakened. The material is likely to tear if stress is at the right angle. The incisions lie parallel to the direction of the seam.

c. Twist Point: The strength is intermediate and the incisions like 45 deg. to the direction of the seam.


Cloth Point Needles

These are used for sewing textile materials rather than the sheet material already described. The points have a round cross section.

The needles are different for the various woven and knitted fabrics.

Knitted fabrics consist of yarns with spaces between them and if a yarn in a knitted fabric is broken the knitted structure may begin to unravel. The requirement in sewing knitted fabrics is :

a. A needle which will slightly deflate the yarns and enter the spaces.

b. A needle of as small a size as possible consistent with needle strength and sewing thread size.

c. A fabric which is sufficiently lubricated that it has flexibility in relation to the movement of the needle.

The shape of the tip of the neele point which best achieves this deflation is a ball shape and the needle is referred to as a ball point needle.

Woven fabric consist of yarns which can have greater or lesser amounts of twist, interlaced with each other at various degrees of density.

For that a needle is needed that goes between the fibres and does not strike and break them.

The shape of the tip of the needle point which best achieves this penetration between the fibres has the appearance of being slighly cone shaped. It is usually referred to as a set point needle.

Sewing-4

Size of Needle

Choice of size is determined by the fabric and the thread combination which is to be sewn.

If needle is too small for the thread, the thread will neither pass freely through the eye nor fit properly into the long groove. As a result it will suffer from excessive abrasion. It may result in

Costly thread breakage in production because the machinist must stop to rethread the needle and possibly also to unpick some of the stitching so that a joint does not show in an important part of the garment.

When sewing heavy plies of material, a fine needle tend to get deflated. It can affect the stitch loop pick up and cause slip stitches, or it can even lead to needle breakage

A break in the situation of multi-needle sewing with fabric running through the folders would be impossible to repair.

If the needle is too large, there will be poor control of the loop formation which may cause slipped stitches.

There will also be holes in the fabric which are too big for the stitches and give an unattractive seam appearance.

In closely woven fabric, there will be a pucker along the seam line due to fabric distortion.

Nomenclature for Needle Size

Metric

d x 100 = Metric Number, where d is in millimeter,

eg. For d = 0.65 mm, number of needle is 0.65x100 =65




Selection of needle and thread size for a particular seaming situation is a question of achieving a balance between the minimum damage due to pucker which is a matter of small needle size and seam strength which requires a substantial needle and thread.

Sewing-3

Sewing Machine Needle

The way in which the fabric is penetrated by the needle during sewing has a direct effect on seam strength and on garment appearance and wearable life.

The functions of the sewing machine needle in general are:

a. To produce a hold in the material for the thread to pass through and to do so without causing any damage to the material
b. To carry the needle thread through the material and there form a loop which can be picked up by the hook on the bobbin case

Anatomy of a Sewing Machine Needle



Butt: It is shaped end of the needle which facilitates insertion into the needle bar or clamp.

Shank:
It is the upper part of the needle which is located within needle bar. It is the support of the needle as a whole and is usually larger in diameter than the rest of the needle for reasons of strength.

Shoulder: It is the section intermediate between the shank and the blade.

Blade: The blade is the longest part of the needle down to the eye. The blade is subjected to the greatest amount of material through which the machine passes.

Long Groove: The long groove in the blade provides a protective channel in which the thread is drawn through the material during stitch formation. Sewing thread can suffer considerably from abrasion during sewing as a result of friction against the fabric. A correctly shaped long groove, of a depth matched to the thread diameter, offers considerable protection to the thread.

Short Groove: The short groove is on the side of the needle which extends a little above and below the eye. It assists in the formation of the loop in the needle thread.

Eye of the Needle: The eye of the needle is the hole extending through the blade from the long groove on one side to the short groove on the other.

Scarf or Clearance Cut: It is a recess across the whole face of the needle just above the eye. This ensures that the loop of the needle thread will be more readily entered by the point of the hook.

The Point of the needle is shaped to provide the best penetration of each type of material.

The Tip is the extreme end of the point which combines with the point in defining the penetration performance.

Sewing-2

Seam Types

Stitched seams are divided into eight classes according to the type and minimum number of components within the seam.

These components which can be the main fabrics of the garment or some additional items such as a lace etc, are termed as being of 'limited' or 'unlimited' width.


where a component is referred to as being limited on one side, that side might be the cut edge of the garment piece that is being seamed.

Where a component is referred to as being unlimited on one side, that edge might be the far edge of the garment panel irrelevent to the seam under consideration.( Figure-1)



Class-I (Superimposed Seams)

It is produced with a minimum of two components both limited on the same side. A variation of the superimposed seam is the french seam.



Class-II ( Lapped Seam)

Seams in this class are produced with a minimum of two components but with these, one is limited on one side and the second is limited on the other side. The components are opposite and at different levels and overlap each other.

Class -III ( Bound Seams)

In this class, seams are produced with a minimum of two components , one is limited to one side with the second is limited on both sides.

Class-iV (Flat Stitching)

In this class, seams are produced with a minimum of two components of which one is limited on one side and the second on the other. The two components are opposite and on the same level. These seams are referred to as flat seams because the fabric edges do not overlap. They may be butted together without a gap and joined across by a stitch which has two needles sewing into each fabric.

Class-V (Decorative Stitching)

Seams in this class are produced with a minimum of two components unlimited on two sides. Any other component is either limited on one side or limited on two sides.



Class-VI (Edge Neating)


It is produced with only one component limited on one side (either on the right or the left). Seam types in this class include those where fabric edges are neated by means of stitches as well as folded hems and edges.

Sewing-1

Sewing

1. Seam: A seam is the application of a series of stitches or stitch types to one or several thicknesses of material.

Stitching is applied to situations where there is only one piece of fabric, such as when fabric edges are neated or hems created, and where decorative sewing is involved.

Objective of Sewing: Are the construction of seams whcih combine the required standards of appearance and performance with in appropriate level of economy in application.

Good Apppearance of Seams: It means smooth fabric joins with no missed or uneven stitches and no damage to the material being sewn.

Performance of Seams: It means the achievement of strength, elasticity, durability, security and comfort, and the maintenance of any specialised fabric properties such as waterproofing or flameproofing.

1. Seams must be strong as the fabric, in directions both parallel to and at right angles to the seam.

2. Seams must be durable to the kind of abrasion experienced in washing and wearing as well as secure against fraying apart or the unravelling of the stitches.

3. A seam in a close fitting garment must not present an uncomfortable ridge or roughness to the skin.

4. It must not damage the fabric along the stitch line.


Factors to be considered while sewing

1. Seam Type: Particular configuration of seams in fabrics.

2. Stitch Type: Particular configuration of threads of in the fabric.

3. The Sewing machine feeding mechanism- It moves the fabric past the needle and enables a succession of stitches to be formed.

4. The needle which inserts the thread into the fabric.

5. The thread which forms the stitch which either holds the fabric together, neatens it or decorates it.

Denim Finishes

I came across these two websites while searching for images and description about denim finishes:

1. The website of cotton incorporated
2. The web site of Textile and Apparel Management at the University of Missouri

I would like to hear more about such websites giving Images and description about denim finishes.

A catalogue on knitting and other defects

This catalogue is available for download on the blog of Aasima Ahmed, Research Assistant, Textile Research & Innovation Centre Lecturer, Fibre Science, Textile Institute of Pakistan.

It is full of illustrations and explanations.

An Amazing Site on Textile Processing

This site on textile processing contains all the relevant information that is normally needed for a person in this industry.

As the site says it is a complete guide to textile processing industry. It has articles on textile processing, textile testing, textile development, affluent treatment

I thank Sazid for leading me to to this site through his blog.