Denim Manufacturing Process- the presentation

Please refer to the following presentation for the denim manufacturing process

Proposed Inspection Process for Indigo Dyed Denim

* A four point system can be adopted, with 9 qualities ( from 9 to 1).

The point distribution is as follows:

upto 3"= 1 point
3-6"= 2 point
6-9"= 3 points
9" and above= 4 points

Any defect across full width = 4 point
All the above defects may be length or width wise.
Length wise one course or fine ends/ up to one meter=4
Starting mark (across the width)=4
Cuttable Defects
-moire
- continuous slub or slubbing weft
- thinck end more than one meter
- major shade variation
-burnt selvedge
- blanket impression
-width variation
-Jala-jerky-chira-wrong drawn- float-snarls-missing ends- more warp breaks- patti-holes-cuts-sever temple mark- more pick findings in short length, double pick
-Slack and tight ends >1m


* From qualities 3-9, only 2 pieces in a single roll are allowed and no piece should be less than 30 meters.

The qualities Criterian can be defineds as follows:

9--> 2 shades allowed, allow 20 points per linear meter which no greater than 2 to 3 4 points defects
8--> 3 shades are allowed, allow 36 points per linear meter no greater than 4, 4 point defects
7--> same as 8 but here we allow upto 5 shades
6--> Allow 72 points per linear meter, upto 3 shades -no greater than 5 to 6 , 4 point defects
5--> same as 6, but 5 shades are allowed.
4--> points should not be greater than 72, any number of shades, any number of 4 point defects. We do not allow patta ( width wide strips)
3--> Same as 4, we can allow patta
2--> same as 3, 5 pieces are allowed ( every piece 10-30 meters each)
1--> any continuous defect is allowed ( pack the piece less than 1 meter)

Shade gradation can be
Dark Shade--> D+
Normal Shade --> D
Light Shade --> D-

Relation between Manual and "l a b" grading system
l, a, b values
D- = 554,654,655
D= 454,555,656
D+= 455,456,556

Tolerance for l a b values--> L = +-0.5, a = +/- 0.5, b= +/- 0.5

Voile, Cambric, Terry voile, shiffon, long cloth, classical oxford, pin-point oxford, Chief Value Cotton

Voile

It is a doubled yarn, highly twisted with count range >60s. It has an square and open construction. The fabric made from it is light weight, transparent, crispy and granular feel. It can be either cotton or P/C. Its trade name is 2 x2 Rubia. 72 epi and 72 ppi.

Cambric

It is a single yarn, rest properties are same as voile.

Terry Voile

It is name of voile with 2/81 high twisted fabric in 67:33 blend which is later carborised to get a 100% polyester fabric.

Shiffon

Count is 62s. Here weft is highly twisted (1400-1500 tpm) polyester filamnet and textured and warp is p/c. 67:33

Long Cloth

It is a plain fabric with special kind of finish which remains for some times even after normal washing.

Poplin Broad Cloth
A tightly woven, subtle variation on a plain-weave fabric, characterised by a very high thread count- 100 to 200 tpi- produces a thin, but relatively opaque fabric with a crisp, hard finishing. Also characteristics of the fabric is its fine horizontal ribbing, produced by the lengthwise warp threads being packed more densly than the crossing weft threads. The ribbing is scarcely noticeable but makes any on-grain stripes very clear and appear solid in color, and it also adds a little shine on the fabric. If the cotton fiber itself has any shine, it will enhance the shine of ribbing and produces a very dressy effect. It comes in solid colors, stripes, plaids and checks.

120 *72
Chambray: It looks solid color but is a plain worked with two colors of yarns, usually a white warp and a colored weft or vice-versa. They are woven in all weights. It can be poplin, or twill or dobby chambray

Classical Oxford
It is like chambray, but in contrast to a chambrays plain weave, oxford cloth is woven in a basket weave. It produces the fabric's soft bulkiness.

Warp is Dyed and weft grey
warp --> 2/40s, Weft --> 2/30s

Pin Point Oxford
When worked in a fine weave, oxford cloth is called a pinpoint oxford.

both warp and weft 2/80s, 144 ends/inch in grey and 60-62 ppi.

Chief Value Cotton

60% cotton, 40% polyester

German Finish

Enzyme treatment. Here fabric gets very good lustre and feel. Also we do a process called weight reduction process ( weight is reduced by 4-5%, so bulkiness in the fabric is given.

Chinos

3/1 twill with 2/40s * 2/30s. When single yarn is used it is called Drill.

Gaberdine
2/1 twill
with 2/40s * 2/30s

Notes on Dyeing of sulphur black on Rope Dyeing Range

1. Process of dyeing of sulphur color:

1st Wash tank: mercerisation by taking 22% NaOH ie. 250 gpl
2nd Wash Tank: Hot Wash
3rd Wash Tank: Cold Wash

2. In 1st and 2nd dye bath take sulphur color 6-8% on the weight of the yarn sheet. Temperature 90 deg. cel. The solution contains the following:

1. solubalised sulphur color: 150 gpl
2. Na2S--> reducing agent: It is added to increase its reducing power
3. Caustinc Soda --> 10 gpl--> reducing agent
4. Wetting agent--> 2gpl
5. Antioxident Sulphide ( Glucose paste--> 5gpl). This is added to prevent the oxidation of of Sulphide solution. It will always remain in reduced form
( Alos if the shade is slightly greyish, one can add tiny tinge of sulpher blue--> 20gpl)

in III, IV and V dye bath--> cold wash
in 6th dye bath. We take H2O2(30%)+Acetic Acid(2:1 by weight). H2O2 acts as an oxidising agent. But as it acts on neutral pH (=7) and after cold bath the solution is slightly alkaline, to make it neutral wil add acetic acid. Acs in alkaline pH, oxidising action of H2O2 will be similar to the bleaching action, which may cause tendering in the fabric.

7th and 8th Dye Bath: Cold Wash

Wash Box Number 4: Here washing is done with detergent and soda ash at 60-70 deg.c

5th and 6th Wash Box: Hot Wash

7th wash Box: Here softner is added at 25 gpl. It is cationic softener with pH 4.5 to 6.5. As during oxidation of sulphur, strength is reduced by 10%. On a yarn sulphur is of two types :
1. Free Sulphur
2. Reacted Sulphur.

The free sulphur will react with moisture in the atmosphere to form:
H2O + S --> H2SO4
Which tenders the yarn. Now at acidic pH reaction is much faster. So we add only a small amount of softener (25 gpl) as against that in indigo which is 100gpl.

3rd Point

Over all during sulphur dyeing and storing, the yarn strength is reduced by 15% as compared to Indigo.

4th point

If ball formation takes place of sulphur dyed warp at loom shed, then we can taken in 4th dye bath little Na2S+Caustic to reduce the free sulphur.