Textile Analysis for Forensic Testing

Textile as used in Forensic Evidence

Fibers represent one of the forensic evidences known as trace evidence.

The forensic examiners must handle a victim with care, to minimize fiber loss. Retrieving the victim's clothing as soon as possible is very necessary to prevent as much fiber loss as possible. Fibers are typically collected using adhesive tape.

The following details are particularly noted when analysing fibers. This helps to determine the source of the fibers.

1. Fiber Type: The presence of less common fibers at a  crime scene or on the clothing of victim or suspect increases its significance.

2. Fiber Colors: It greatly influences the significance of fiber comparison. Fading and discoloration further adds significance to a fiber association.

3. Number of Fibers: The greater the number of fibers on the body of a suspect or victim,  the more is the likely hood of a direct contact between individuals, however converse may not be true.

4. Fabric type: Loosley knit or woven fabric or new fabric shed more fibers.

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A Note on Medical Textiles

Textiles act as an interface between man and treament. Depending upon the area of application, the medical textiles are categorises as Non-implantable, implantable and healthcare and hygiene products.

Non implantable material are external to the body, with or without skin contact. It includes absorbant pad, bandages and plasters among others. These material should have good padding characteristics and should be non sticking to the wound. Air and vapor permeability is requrired so that the material is comfortable to the patient. They should have high absorbancy and should be soft and pliable.

Implantable materials are used in place of defective body parts. It includes sutures and soft tissue implants. These materials should have compatibility with the natural body systems. They should be durable and resistant to alkali and acidic media. Of course, they should have functionality for the purpose for which they are applied.

Healthcare and hygine products are not directly used in medical treatment, rather they are used for good hygiene application and healthcare. It includes surgical clothing and surgical covers. They should have high bacterial and viral resistance. They should be hygienic and should have softness and breathablitity. They should have required strength.

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Some Facts about Linen

1. Flax yarns and fabrics increase about 20% in strength on wetting. Linen is therefore stronger than cotton when it comes to washing.

2. Linen can absorb upto 20% of its own weight of moisture while still feeling dry to the touch. That explains why Linen cloth are always fresh and cool.

3. The tensile strength of Linen is twice as high as that of cotton and 3 times as that of wool.

4. Linen reduces gamma radiation almost by half and protects humans against solar radiation.

5. Linen Cloth does not accumulate static electricity- even 10% of linen in a blend is enough to eliminate the static electricity effect.

6. Heat conductivity of Linen is 5 times as high as that of wool and 19 times as that of silk. In hot weather, those dressed in Linen clothes are found to show the skin temperature 3-4 deg below those wearing silk and cotton.

 Among all the linens, Irish Linen is always known to be the best. Linen is an important fiber for Ireland, so much so that stamps and coins are minted showing linen leaves. Source

You can view the production process of Linen from here

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Varanasi Saris- Process Notes

Notes on Varanasi Silk Saris

A Scenic View of the Ganges

Warp and Weft

Loom- Note the two Jacquards

A Close-up view of the Cloth Roll

Rangkaat Sari - Different Colored weft - Interlock technique

Card for Jacquard- Not Interchangeable for other machines

Temple- 6 nails- Unlike Chanderi come from Below

Dyeing of Body and Palla

A View of the Karkhaana- No Jaalas anymore

The warp used is 20/22 denier filament silk. 20/22 is called so because normally a silk fiber is of 2 denier. When 11 such filaments are taken then it becomes 22 denier. However, while reeling one filament may get broaken which means the denier is 20. Hence it is called 20/22 denier. Apart from this 14/18, spun, tussar , 16/18 and Pashmina are also used in the warp. Weft normally used is Katan. Normally for plain weave base 4 heald shafts are used in groups of 2. For Tanchui with Satin base more heald shafts are used. Jacquards are used for extra weft figuring. There can be upto three jacquards, one for weaving body motif, one for palla and one to set Konia etc. Min. warp size can be two saris. Jacquard can be 120 hooks or 160 hooks depending upon the design. Cards cut for one jacquard cannot be interchanged for the other.

Zari

Zari comes in 220 grams bundle and the fineness is denoted by Gajas. If 220 grams has 1200 yards, it is called 1200 gaja if this bundle has 1750 yards, it is called 1750 Gaja. and if it has 3700 yards, it is called 3700 gaja. 1750 and 3700 yard zaris are most commonly used. Zari comes in four quality plastic, Powder, Tested and Real Zari. Plastic zari is also called Kalabattu. Poweder zari has a thinner coating then tested zari and plastic has a synthetic base. In all the zaris except Real, the copper wire is wrapped over a cotton, viscose or synthetic and it is coated with gold or silver. Generally tested zari is also called half fine zari. Also in powder zari the inner core is twisted rayon over which artificial gold color powder is super imposed to obtain the lustrous appearance.However this lace get blacken after some use.3700 Gaja tested Zari has polyester as a base ( 30 denier) with copper covering and siliver or gold electroplating. The thicker zaris has cotton as the core. The Silver coated zari is called Rupa and Gold coated sari is called Sona. The best zari suppliers are AVJ from Surat or Locat supppliers like Uma. Zari comes in three shades; dark, light and medium. To subdue the effect of zari, it can be twised with Resham and used.  An amazing presentation on Zardozi work can be seen here.

Dyes

Dyes used are acid and metal complex for silk and Vat/reactive for cotton.  The colors of Varanasi Saris are fast and no staining is observed.

Preserving Varanasi Saris

The best way to preserve a Varanasi Sari is to keep it in the Mull cloth ( no starch, washed). Plastic is not recommened. It should be dry cleaned.

Finishing of Varanasi Saris

Generally after sari is finished it is then passed through cold calendar to give it a sheen and delivered.  

Other Notes

Maximum weight variation in two Varanasi saris willl be 20-50 grams per sari. Organza sari is called Kora. 

Other Readings:

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An interesting reading is about the use of Condoms in making Varanasi Saris. 

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