OEcotextiles

Leather has become the sign of a luxurious – and durable – choice for practically any product you can think of.  As the ads say, “the rich scent, luxurious texture and easygoing attitude” makes it a popular choice.

Leather has been around as long as  people  –  ancient peoples used materials that were available, like bark and plant tannins, alum, earth minerals, fish oils, animal brains, lime and smoke to preserve animal skins.  The process took a long time – from 1 to 12 months.  But today’s leather is a far cry from  early leathers because horribly toxic synthetic chemicals have replaced the older tanning chemicals (usually in the interest of time – chrome tanning takes only a fraction of the time as does “natural” tanning); modern leather tanneries are frighteningly toxic and the animal husbandry aspect is sad and sickening. There are a very few ethical tanneries, but so far I can count them on one hand. [1]

But leather –  the skin of a dead animal – is meant to decompose.  What do you think has to be done to that skin so it doesn’t decompose? We covered this topic in a former post ( click here to read that), but basically the tanning of leather is in the top 10 of the world’s worst pollution threats –  at #5 – directly affecting more than 1.8 milllion people. [2] More than 90 percent of Bangladeshi tannery workers suffer from some kind of disease — from asthma to cancer — due to chemical exposure, according to a 2008 survey by SEHD, a local charity, with local residents being almost as badly affected. [3]

What chemicals are used to create such terrible pollution? In all, around 250 chemicals are used in tanning. Skins are transferred from vat to vat, soaked and treated and dyed.   Chemicals include alcohol, coal tar , sodium sulfate, sulfuric acid, chlorinated phenols (e.g. 3,5-dichlorophenol), chromium (trivalent and hexavalent), azo dyes, cadmium, cobalt, copper, antimony, cyanide, barium, lead, selenium, mercury, zinc,  polychlorinated biphenyels (PCBs), nickel, formaldehyde and pesticide residues.[4]  At the same time, toxic gases like ammonia, hydrogen sulfide, and carcinogenic arylamines are emitted into the air. The smell of a tannery is the most horrifyingly putrid smell on earth.

But people really want leather – so what’s an industry to do?

Enter Pleather, made from oil in the form of plastic – either PVC or polyurethane. Pleather is simply a slang term for “plastic leather”, made by bonding the plastic to a fabric backing.   It’s often used as an inexpensive substitute for leather, but the fashion industry has adopted it big time. It is lighter than leather, and it does not decompose as quickly as leather. It’s also supposed to be much more durable than leather.

The PVC version does not breathe and can be very hard to clean – it’s not often used for surfaces that come in contact with the skin.   The polyurethane version is usually machine washable and can be dry cleaned. It’s also slightly breathable, softer, and more flexible.

Is this a good alternative? Given that every manufactured product has an unavoidable environmental cost, neither leather nor pleather is particularly green. The PVC version of pleather is made from polyvinyl chloride, which is loathed by Greenpeace, calling it the “most damaging plastic on the planet,” because its production releases dioxins and persistent organic pollutants. The polyurethane version doesn’t have quite the same toxicity problems as PVC, but plenty of CO2 is emitted during the production. According to the Association of Plastics Manufacturers in Europe, producing a pound of polyurethane emits 3.7 lbs. of CO2 – slightly less than burning a gallon of gas.[5]

YouTube’s version (shown below) shows the production of PVC pleather: Pleather is made by coating a paper backing (embossed to look like leather) with PVC (polyvinyl chloride). First, a petroleum based plasticizer; a UV stabalizer and a fire retardant are mixed in solution, then powdered vinyl is added. Dyes are put into a different tub, then they pour in the liquid vinyl. Next the large roll of paper with a leather like texture is coated with the liquid vinyl. It is baked in an oven to harden the vinyl, which takes on the paper’s texture. A second batch of vinyl is prepared which contains a thickening agent, and it is poured onto the first layer. Then the double layered vinyl goes through the oven again. Fabric (from cotton to polyester) is adhered to the back, and the paper is peeled off to reveal the leather pattern. Here is the visual production from YouTube:

Properly manufactured pleather should be calendered – which means passing the material between two rollers to make the surface shiny.   If it is not calendered, it is considered “cheap” pleather and its durability is compromised.

But maybe if we wait just a bit there will be even better alternatives: Richard Wool, a professor of chemical and biomolecular engineering at the University of Delaware, has been working on a leather alternative which is entirely non-plastic, and bio-based: it’s made from flax or cotton fibers, which are laminated together in layers using palm, corn, soybean or other plant oils to create a leather-like material.   And unlike pleather – it’s breathable. Wool plans to call his product Green Engineered Material or GEM. But he’s looking for muscle and money to get the product moving forward.[6]

[1] Organic Leather, in California, is trying to create high-quality and stylish leather while working to transform the industry and educate consumers.  See their white paper: http://www.organicleather.com/organic_leather_white_paper.pdf

[2] http://www.globe-net.com/articles/2011/november/11/world’s-10-worst-toxic-pollution-problems/

[3] Barton, Cat, “Workers pay high price at Bangladesh tanneries”, AFP, Feb. 2011

[4] Ibid.

[5] Koerner, Brendan, “Wheather the Leather be Pleather”, Slate online, http://www.slate.com/articles/health_and_science/the_green_lantern/2007/12/whether_the_leather_be_pleather.html

[6] http://www.newarkpostonline.com/news/article_c67d7f46-8747-5bb0-abfe-d50ce305f767.html