Unit - Chemistry of Textiles: Treatments
  1. Felt
  2. Scotchgard
  3. Dry Cleaning
  4. Flame Retardants

Felt

Felt is a non-woven cloth that is produced by matting, condensing and pressing woollen fibres. While some types of felt are very soft, some are tough enough to form construction materials. Felt can be of any colour, and made into any shape or size.

Carroting
From the mid-17th to the mid-20th centuries, a process called "carroting" was used in the manufacture of good quality felt for making men's hats. Beaver, rabbit or hare skins were treated with a dilute solution of mercuric nitrate, [Hg(NO3)2]. The skins were dried in an oven where the thin fur at the sides turned orange - giving rise to the name. Pelts were stretched over a bar in a cutting machine and the skin sliced off in thin shreds, the fleece coming away entirely. The fur was blown onto a cone-shaped colander, treated with hot water to consolidate it, the cone peeled off and passed through wet rollers to cause the fur to felt. These 'hoods' were then dyed and blocked to make hats. This toxic solution and the vapours it produced resulted in widespread cases of mercury poisoning among hatters, possibly giving rise to the expression "Mad as a hatter".

Mad Hatter - Alice in Wonderland
Videos showing how Stetson or Australian Akubra hats are made.

Scotchgard
Scotchgard is a 3M brand of products, that act as a stain repellent and durable water repellent when applied to fabric, furniture, and carpets, protecting them from later stains.
The original formula for Scotchgard was discovered accidentally in 1952 by 3M chemists Patsy Sherman and Samuel Smith. Sales began in 1956, and in 1973 the two chemists received a patent for the formula.
Two related "key ingredients" of Scotchgard are perfluorooctane sulfonate (PFOS) and perfluorooctanesulfonamide (PFOSA), a PFOS precursor. In May 2000, under USEPA pressure, 3M announced the phaseout of the production of perfluorooctanoate (PFOA), PFOS, and PFOS-related products. 3M had monitored the efffect on health for some years.

In May 2009 PFOS was classified as a persistent organic pollutant (POP) by the Stockholm Convention.

Since June 2003, after 3M reformulated Scotchgard it replaced PFOS with perfluorobutanesulfonic acid (PFBS). PFBS has a much shorter half-life in people than PFOS (a little over one month vs. 5.4 years).
perfluorobutanesulfonic acid (PFBS)
The structure of perfluorobutanesulfonic acid (PFBS)

Dry Cleaning
Dry cleaning is any cleaning process for clothing and textiles using a chemical solvent other than water, that is, it is not really dry just that they are not exposed to water. The solvent used was typically tetrachloroethylene (perchloroethylene), which the industry calls "perc". It was used to clean delicate fabrics that could not withstand the rough and tumble of a washing machine and clothes dryer; it can make labour-intensive hand washing unnecessary.
tetrachloroethylene- perc
The structure of tetrachloroethylene (perc)


Dry Cleaning Solvents

Historical

Modern


Decamethylcyclopentasiloxane silicone_D5
The structure of Decamethylcyclopentasiloxane (D5), used in "GreenEarth Cleaning"
PERC cleanup video

Flame Retardants
The term flame retardants includes a diverse group of chemicals that are added to manufactured materials, such as plastics and textiles, and surface finishes and coatings. Flame retardants inhibit or delay the spread of fire by suppressing the chemical reactions in the flame or by the formation of a protective layer on the surface of a material. They may be mixed with the base material (additive flame retardants) or chemically bonded to it (reactive flame retardants). Mineral flame retardants are typically additive while organohalogen and organophosphorus compounds can be either reactive or additive.

See a commercial demo for a Flame Retardant

Acknowledgements.
Much of the information in these course notes has been sourced from Wikipedia under the Creative Commons License. Students taking this course will be expected to contribute to Wikipedia as a part of their course assignments.

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Created February 2013. Links checked and/or last modified 3rd November 2016.
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