What kind of fabric for your new sofa?

11 06 2015

 

We’ve looked at the frame, suspension system and cushioning on a sofa; next up:  fabric.  We consider fabric to be a very important, yet certainly misunderstood, component of furniture.  It can make up 40 – 45% of the price of a sofa.    So we’ll be breaking this topic up into several smaller bite size portions:  after a general discussion of what kind of fabric to choose for your lifestyle,  we’ll look at the embodied energy in your fabric choice (next post), and then finally we’ll take a look at why an organic fabric is better for you (as well as the rest of us).

One thing to remember is that there is much more fabric used in constructing an  upholstered piece of furniture than just the decorative fabric that you see covering the piece – a typical “quality” sofa also uses about 20 yards of decorative fabric, plus 20 yards of lining fabric, 15 yards of burlap and 10 yards of muslin, for a total of 65 yards of fabric!

So what do people look for in an upholstery fabric?

After color, fabric durability is probably top of everybody’s list.  Durability translates into most people’s minds as “heft” – in other words, lightweight cotton doesn’t usually come to mind.  A fabric with densely woven yarns tends to be more durable than a loosely woven fabric.  Often people assume leather is the best choice for a busy family.  We did a post about leather – if you’re at all considering leather, please read this first (https://oecotextiles.wordpress.com/2012/05/22/leather-furniture-what-are-you-buying/ ).    Another choice widely touted is to use Ultrasuede.  Please see our post about this fabric if you’re considering Ultrasuede: https://oecotextiles.wordpress.com/2010/09/08/is-ultrasuede%c2%ae-a-green-fabric/.

Equally important in evaluating durability is the length of the fibers.  Cotton as a fiber is much softer and of shorter lengths than either hemp or linen, averaging 0.79 -1.30 inches in length.  Hemp’s average length is 8 inches, but can range up to 180 inches in length. In a study done by Tallant et. al. of the Southern Regional Research Laboratory,  “results indicate that increases in shortfibers are detrimental to virtually all yarn and fabric properties and require increased roving twist for efficient drafting during spinning. A 1% increase in fibers shorter than 3/8 in. causes a strength loss in yarns of somewhat more than 1%.”[1]    In fact, the US textile industry has  advocated obtaining the Short Fiber Content (SFC) for cotton classification.  SFC is defined as the percentage of fibers shorter than ½ inch.  So a lower cost sofa upholstered in cotton fabric could have been woven of short fiber cotton, a cheaper alternative to longer fiber cotton and one which is inherently less durable – no matter how durable it appears on the showroom floor.

Patagonia, the California manufacturer of outdoor apparel, has conducted  tests on both hemp and other natural fibers, with the results showing that hemp has eight times the tensile strength and four times the durability of other natural fibers.   Ecolution had a hemp twill fabric tested for tensile and tear strength, and compared the results with a 12-oz cotton denim.  Hemp beat cotton every time:   Overall, the 100% hemp fabric had 62% greater tear strength and 102% greater tensile strength. [2]   And polyester trumps them both – but that’s a whole different ballgame, and we’ll get to that eventually.

There is a high correlation between fiber strength and yarn strength.  People have used silk as an upholstery fabric for hundreds of years, and often the silk fabric is quite lightweight;  but silk is a very strong fiber.

In addition to the fiber used, yarns are given a twist to add strength. This is called Twist Per Inch or Meter (TPI or TPM) – a tighter twist (or more turns per inch) generally gives more strength.  These yarns are generally smooth and dense.

So that brings us to weave structure.  Weave structures get very complicated, and we can refer you to lots of references for those so inclined to do more research (see references listed at the end of the post).

But knowing the fibers, yarn and weave construction still doesn’t answer people’s questions – they want some kind of objective measurement.  So in order to objectively compare fabrics,  tests to determine wear were developed (called abrasion tests), and many people today refer to these test results as a way to measure fabric durability.

Abrasion test results are supposed to forecast how well a fabric will stand up to wear and tear in upholstery applications.  There are two tests generally used:  Martindale  and Wyzenbeek (WZ).  Martindale is the preferred test in Europe; Wyzenbeek is preferred in the United States.  There is no correlation between the two tests, so it’s not possible to estimate the number of cycles that would be achieved on one test if the other were known:

  • Wyzenbeek (ASTM D4157-02):  a piece of cotton duck  fabric or wire mesh is rubbed in a straight back and forth motion on a      piece of fabric until “noticeable wear” or thread break is evident.  One back and forth motion is called a “double rub” (sometimes written as “dbl rub”).
  • Martindale (ASTM D4966-98):  the abradant in this test is worsted wool or wire screen, the fabric specimen is a circle or round  shape, and the rubbing is done in a figure 8, and not in a straight line as in Wyzenbeek.  One circle 8 is a cycle.

The Association for Contract Textiles performance guidelines lists the following test results as being suitable for commercial fabrics:

Wyzenbeek Martindale
Low traffic / private spaces 15,000 20,000
High traffic / public spaces 30,000 40,000

According to the Association for Contract Textiles, end use examples of “low traffic” areas where 30,000 WZ results should be appropriate include executive offices, corporate boardrooms, luxury hotel lobbies, suites and guest rooms. Areas of “high traffic” include: single shit corporate offices, waiting rooms, and high traffic hotel lobbies and guest rooms.

Sina Pearson, the textile designer, has been quoted in the Philadelphia Inquirer as saying that 6,000 rubs (Wyzenbeek) may be “just fine” for residential use”[3]   The web site for Vivavi furniture gives these ratings for residential use:

Wyzenbeek
from to
Light use 6,000 9,000
Medium use 9,000 15,000
Heavy use 15,000 30,000
Maximum use >30,000

Theoretically, the higher the rating (from either test) the more durable the fabric is purported to be.  It’s not unusual for designers today to ask for 100,000 WZ results.  Is this because we think more is always better?  Does a test of 1,000,000 WZ guarantee that your fabric will survive years longer than one rated only 100,000 WZ?  Maripaul Yates, in her guidebook for interior designers, says that “test results are so unreliable and the margin of error is so great that its competency as a predictor of actual wear is questionable.”[4]  The Association for Contract Textiles website states that “double rubs exceeding 100,000 are not meaningful in providing additional value in use.  Higher abrasion resistance does not necessarily indicate a significant extension of the service life of the fabric.”

The reason these test results might not be predicative is because there are, apparently, many ways to tweak test results. We’ve been told if we don’t like the test results from one lab, we can try Lab X, where the results tend to be better.  The reasons that these tests produce inconsistent results are:

1. Variation in test methods:       Measuring the resistance to abrasion is very complex.  Test results are affected by many factors that include the properties and dimensions of  the fibers; the structure of the yarns; the construction of the fabrics;  the type, kind and amount of treatments added to the fibers, yarns, or fabric; the time elapsed since the abradant was changed;  the type of  abradant used; the tension of the specimen being tested,the pressure between the abradant and the specimen…and other variables.

2. Subjectivity:    The  measurement of the relative amount of abrasion can be affected by the method of evaluation and is often influenced by the judgment of the operator.  Cycles to rupture, color change, appearance change and so forth are highly variable parameters and subjective.

3. Games Playing:     Then there is, frankly, dishonest collusion between the tester and the testee.  There are lots of games that are played. For instance, in Wyzenbeek, the abradant, either cotton duck or a metal screen, must be replaced every million double rubs. If your fabric is tested at the beginning of that abradant’s life versus the end of its life, well… you can see the games. Also, how much tension the subject fabric is under –  the “pull” of the stationary anchor of the subject fabric, affects the  rating.

In the final analysis, if you have doubts about the durability of a fabric,  will any number of test results convince you otherwise?  Also, if your heart is set on a silk  jacquard, for example, I bet it would take a lot of data to sway you from your heart’s desire.  Some variables just trump the raw data.

REFERENCES FOR WEAVE STRUCTURE:

1.  Peirce, F.T., The Geometry of Cloth Structure, “The Journal of the Textile Institute”, 1937: pp. 45 – 196

2. Brierley, S. Cloth Settings Reconsidered The Textile Manufacturer 79 1952: pp. 349 – 351.

3. Milašius, V. An Integrated Structure Factor for Woven Fabrics, Part I: Estimation of the Weave The Journal of the Textile Institute 91 Part 1 No. 2 2000: pp. 268 – 276.

4. Kumpikaitė, E., Sviderskytė, A. The Influence of Woven Fabric Structure on the Woven Fabric Strength Materials Science (Medžiagotyra) 12 (2) 2006: pp. 162 – 166.

5. Frydrych, I., Dziworska, G., Matusiak, M. Influence of Yarn Properties on the Strength Properties of Plain Fabric Fibres and Textile in Eastern Europe 4 2000: pp. 42 – 45.

6. ISO 13934-1, Textiles – Tensile properties of fabrics – Part 1: Determination of Maximum Force and Elongation at Maximum Force using the Strip Method, 1999, pp. 16.

[1] Tallant, John, Fiori, Louis and Lagendre, Dorothy, “The Effect of the Short Fibers in a Cotton on its Processing Efficiency and Product Quality”, Textile Research Journal, Vol 29, No. 9, 687-695 (1959)

[2]  http://www.globalhemp.com/Archives/Magazines/historic_fiber_remains.html

[3] ‘How will Performance Fabrics Behave”, Home & Design,  The Philadelphia Inquirer, April 11, 2008.

[4] Yates, Maripaul, “Fabrics: A Guide for Interior Designers and Architects”, WW. Norton and Company.

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What’s pleather?

16 07 2014

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





What about chrome-free, or “eco” leather?

29 05 2012

With the increased interest in avoidance of certain chemicals and industrial products that are particularly harmful to our environment, it’s not surprising that manufacturers are becoming ingenious in pointing out attributes that play to this script.  So we now see claims for “chrome free” leather, or for “eco friendly” leather.

In last week’s post, I pointed out two kinds of leather tanning – chromium and vegetable. Although most leather is tanned using chromium (from 80 – 95% of all leather produced[1]) there is a third type of leather tanning, called aldehyde tanning, which like vegetable tanning does not use chromium.  Let’s revisit leather tanning for a minute:

  1. Sometimes leather manufacturers will tell you that they don’t use the toxic form of chromium in tanning – the toxic form is called chromium IV or hexavalent chromium.  And that is correct:  chromium tanned leathers use chromium III salts (also called trivalent chromium) in the form of chromium sulfate.  This form of chromium is found naturally in the environment and is a necessary nutrient for the human body.   However, the leather manufacturers fail to explain that  chromium III oxidizes into chromium IV in the presence of oxygen combined with other factors, such as extremes in pH.  This happens during the tanning process.  Chromium-tanned leather can contain between 4 and 5% of chromium [2] – often hexavalent chromium, which produces allergic reactions and easily moves across membranes such as skin.  End of life issues, recovery and reuse are a great concern – chromium (whether III or IV) is persistent (it cannot be destroyed) and will always be in the environment.   Incineration, composting and gasification will not eliminate chromium.
  2. Vegetable tanning is simply the replacement of the chromium for bark or plant tannins – all other steps remain the same.  And since there are about 250 chemicals used in tanning, the replacement of chromium for plant tannins, without addressing the other chemicals used, is a drop in the bucket.   Last week I mentioned some of the other 249 chemicals routinely used in tanning:  alcohol, coal tar , sodium sulfate, sulfuric acid, chlorinated phenols (e.g. 3,5-dichlorophenol), azo dyes, cadmium, cobalt, copper, antimony, cyanide, barium, lead, selenium, mercury, zinc, polychlorinated biphenyels (PCBs), nickel, formaldehyde and pesticide residues.[3]   Here are the steps to creating leather :
  3. Aldehyde tanning is the main type of leather referred to as “chrome-free”, and is often used in automobiles and baby’s shoes.  Aldehyde tanning is often referred to as “wet white” due to the pale cream color it imparts to the skins.  But aldehydes are a group of chemicals that contain one chemical which many people are familiar with: formaldehyde.  And we all know about formaldehyde: it is highly toxic to all animals; ingestion of as little as little as 30 mL (1 oz.) of a solution containing 37% formaldehyde has been reported to cause death in an adult human[4]  and the Department of Health and Human Services has said it may reasonably be anticipated to be a carcinogen.  Aldehyde tanning essentially uses formaldehyde, which reacts with proteins in the leather to prevent putrefication.  BLC Leather Technology Centre,  a leading independent leather testing center, states that leathers should contain no more than 200ppm of formaldehyde for articles in general use. If the item is in direct skin contact this should be 75ppm, and 20ppm for items used by babies (<36 months). Typically, with modern tanning techniques, leathers contain 400ppm or less.[5]   Yet that far exceeds levels set elsewhere – in New Zealand, for example, acceptable levels of formaldehyde in products is set at 100 ppm[6]  – the European Union Ecolabel restricts formaldehyde to 20 ppm for infant articles, 30 ppm for children and adults, while GOTS prohibits any detectable level.

BLC Leather Technology Centre Ltd.  commissioned a study by Ecobilan S.A (Reference BLC Report 002)  to do a life cycle analysis to evaluate the various tanning chemicals, to see if there was an environmentally preferable choice between chrome, vegetable and aldehyde based processes.  The result?  They found no significant differences between the three  – all have environmental impacts, just different ones.  These LCA’s demonstrate that tanning is just one of the impacts – other steps may have equal impacts.   Chrome was sited as having the disadvantage of being environmentally persistent. “Another consideration, in terms of end-of-life leather or management of chrome tanned leather waste, is the possibility of the valency state changing from the benign Cr III to the carcinogenic Cr VI.”[7]

So much for “chrome free” leather.  What about claims for “eco leather”?

In the strict sense of the definition, the term “eco leather” is meaningless. However, retailers want to imply improved environmental performance. So how can you evaluate their claims for “eco leathers”?

There are two main considerations in making leather:

  • How is it manufactured?
  • What inputs are used to produce it?

Research has shown that a significant part of the environmental impact of leather is in the manufacturing process.  In this respect it is the environmental stewardship practice of tanners coupled with chemical selection that should determine how eco friendly a leather is.  The following areas of leather manufacture have the most significant potential impact:

  • Management of restricted substances
  • Energy consumption
  • Air emissions
  • Waste management (hazardous and non hazardous)
  • Environmental management systems
  • Water consumption
  • Control of manufacturing processes
  • Effluent treatment
  • Chrome management
  • Traceability of material

In terms of the selection of inputs, we should consider the use of certain materials that could give an improved eco profile to leather. These include:

  • Biodegradable wetting agents for soaking
  • Reduced sulphide processing
  • Non synthetic or polymeric re-tannage systems
  • optimized dyestuffs
  • Vegetable oil based fatliquors
  • Optimised finishing systems to reduce waste such HVLP or roller coating
  • Biodegradable in 12 months or less

In summary, although there is no current definition, these are the key elements which should determine an “eco leather”:

  1. Control of leather manufacturing processes
  2. Clean technology chemical selection in the process
  3.  Effective management of restricted substances within the leather
  4. A measure of the end of life impact

As I mentioned in last week’s post, the production of leather can be a hellish life for the animal.  I have found only one company, Organic Leather, which looks beyond the production of the leather itself to the important questions of animal husbandry and land management practices which provide the skins, and incorporate these into a tanning process which “prevents further toxicity entering our environment and our bodies.”

The Leather Working Group (LWG)   is a multi-stakeholder group[8], whose purpose is  “to develop and maintain a protocol that assesses the compliance and environmental performance of tanners and promotes sustainable and appropriate environmental business practices within the footwear leather industry.”   The LWG, in conjunction with BLC Leather Technology Center Ltd., operates an eco rating system for leather. (This sort of mark is known as a first or second party certification, and lacks – I believe – the credibility of a true third party certification.)   Retailers, brands or tanners who are able to meet the requirements of this standard are eligible to use the EcoSure mark. To be eligible to use this mark tanneries must have achieved at least a Bronze award in the LWG Tannery Environment Auditing Protocol,  and the finished leather on which the mark is to be used must meet the requirements of the audit and testing regime. (to see the audit form, click here  ).

One issue which is a hot topic in leather production is that of deforestation and the sourcing of skins from Brazil – cattle ranching in Brazil accounted for 14% of global deforestation and ranches occupy approximately 80% of all deforested land in the Amazon.[9]  Greenpeace and the National Wildlife Federation (NWF) aims to stop all deforestation in the Amazon by encouraging the meat processors to insist that their suppliers register their farms and map and log their boundaries as a minimum requirement. They also encourage companies to cancel orders with suppliers that are not prepared to stop deforestation and adhere to these minimum requirements.  Many of the LWG member brands have  made commitments to a moratorium on hides sourced from farms involved in deforestation and LWG itself has a project to identify and engage with the key stakeholders in Brazil, investigate traceability solutions, conduct trials and implement third party auditing solutions.


[1] Richards, Matt, et al, “Leather for Life”, Future Fashion White Papers, Earth Pledge Foundation

[2] Gustavson, K.H. “The Chemistry of Tanning Processes” Academic Press Inc., New York, 1956.

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

[4] Agency for Toxic Substances & Disease Registry, “Medical management guidelines for formaldehyde”, http://www.atsdr.cdc.gov/mmg/mmg.asp?id=216&tid=39

[5] BLC Leather Technology Center Ltd, “Technology Restricted substances – Formaldehyde”, Leather International,  November 2008,  http://www.leathermag.com/news/fullstory.php/aid/13528/Technology_Restricted_substances-Formaldehyde.html

[6] “Evaluation of alleged unacceptable formaldehyde levels in Clothing”, Wellington, New Zealand: New Zealand Ministry of Consumer Affairs, October 17, 2007.

[8] Currently the consumer brands involved with the LWG are: Adidas-group, Clarks International, Ikea of Sweden, New Balance Athletic Shoe, Nike Inc, Pentland Group including (Berghaus, Boxfresh, Brasher, Ellesse, Franco Sarto, Gio-Goi, Hunter, KangaROOS, Mitre, Kickers (UK), Lacoste Chaussures, ONETrueSaxon, Radcliffe, Red or Dead, Speedo, Ted Baker Footwear), The North Face, The Timberland Company, Wolverine World Wide Inc including (CAT, Merrel, Hush Puppies, Patagonia, Wolverine, Track n Trail, Sebago, Chaco, Hytest, Bates, Cushe, Soft Style). New brands recently joined are Airwair International Ltd, K-Swiss International, Marks & Spencers and Nine West Group.

[9] “Broken Promises: how the cattle industry in the Amazon is still connected to deforestation…” Greenpeace, October 2011; http://www.leatherworkinggroup.com/images/documents/Broken%20promises%20-%20Oct11FINAL.pdf





Leather furniture – what are you buying?

22 05 2012

People like to buy leather furniture because of leather’s durability (it’s advertised to last a lifetime) – even though it demands a bit of attention to keep it looking its best.   Manufacturers also like to portray leather (perhaps because of its high price) as conveying luxury and sophistication.

Leather has been used practically forever –  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 natural tanning process takes a long time – from 1 to 12 months.  It often also relies on physical manipulation.

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]

Let’s take a look at what that leather on your sofa means to us today.

Many people think that leather is a by-product of the meat industry, and that buying leather does not increase the number of animals slaughtered.  But in the case of some animals, the meat is the by product – on ostrich farms, the leather account for 80% of the dead animal’s value.[2]  Some leather – made from more exotic animals like kangaroos, zebras, seals, snakes, lizards and even sharks – are either raised or hunted specifically for their skins. [3] Regardless of how you define it, the skin is not a “leftover” since processing it as leather accounts for about 10% of the slaughtered animal’s overall value,[4] generating significant profits for both factory farms and the leather trade itself.  In fact, without the lucrative sale of animal skins for leather, factory farms would not even be able to turn a profit by selling meat alone. Ultimately, buying leather products subsidizes factory farms while providing financial incentive for them to produce more leather.

Most leather comes from cattle who are slaughtered for meat, worn-out dairy cows who no longer produce enough milk to be profitable, and veal calves whose soft skin is particularly valuable.  These animals often suffer in many ways that are detailed on various websites (such as Liberation BC: Speaking out for Animals and PETA) – it is such a gut wrenching, gruesome story that I can’t even bring myself to talk specifics.

Let’s face it – leather is the skin of a dead animal.  It is, by nature, meant to decompose.  What do you think has to be done to that skin so it doesn’t decompose?

After 75 years at the bottom of the Atlantic, few items aboard the R.M.S. Titanic had survived the ravages of saltwater.  But leather items hadn’t rotted away because their chrome tanning prevented their decay.[5]

The global leather industry is composed of three sectors of activity: animal husbandry and slaughter, tanning, and product manufacturing. Tanning is the stage in which raw leather is processed and made more durable so that it doesn’t decompose in your living room. Tanning consists of two major processes:

  1. Wet blue production (so called because the semi-finished hide is given a chrome bath which imparts a blusih tint).  This process involves removing unwanted substances (salt, flesh, hair, and grease) from a rawhide (by soaking in a bath of lime and sodium sulfide to dissolve hair and flesh), trimming it, treating it to impart the desired grain and stretch, and finally soaking it in a chrome bath to prevent decomposition.  This step is far more polluting than finishing, generating 90% of the water pollution associated with leather tanning.[6]
  2. Finishing – Finishing involves splitting, shaving, re-tanning, and dying the wet blue.

Often leather is advertised as being “aniline dyed”.  That means the leather is dyed for color without any pigments applied.  These dyes enhance the subtle variations of each hide and the leather does not lose any structure or grain pattern.  It is often considered to be of a higher quality than other types of dyed leather because aniline dyed leathers develop a  distinctive patina over time. Only premium hides with the most pleasing color and texture are selected for this category, less than 5% of all upholstery hides in the world.

Semi-aniline, also referred to as “Aniline Plus”,  is also advertised.  These leathers are first dyed in the penetrating aniline dyes. Then a topcoat is applied to even out the color of the hide surface. The topcoat also serves to create fading- and soil-resistant pieces.  They retain a great amount of the softness of aniline dyed hides because the natural top grain is left intact. A much larger proportion of the worldwide hide supply is suitable for this class of leather and as a result they are more moderately priced than pure aniline dyed hides.

So now we come to the part about the problems with using leather – you knew it was coming.

According to the results of a three year study to address health impacts of pollution from the Blacksmith Institute, which works to solve pollution problems in the developing world,  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.[7]

Blacksmith’s Bret Ericson, who managed the three-year project, says:  “These are not large-scale, multinational corporations that are responsible for this pollution. Typically, it’s low income, small-scale industries who have no emissions controls,” often because these outdated industries remain unregulated.

Because of the acknowledged hazards of leather production, the process is being discontinued in most European countries and the U.S., and operations are moving overseas.   Because of the relatively inexpensive cost of labor and materials, over half the world’s tanning activity occurs in low- and middle-income countries.  Leather tanneries are highly concentrated in Nepal, Bangladesh and India.  Bangladesh Tanners Association President M. Harun Chowdhury said, “Most of the European countries and USA are discontinuing leather processing, as [the] leather industry is an environmentally hazardous one.”[8]

Spurred by retailer demand in the West, leather buyers in Asia have been welcomed with open arms by governments all-too-eager for a slice of the global market, and happy to turn a blind eye to non-existent safety regulations in return. Regulations governing tannery pollution have been on the books for decades in countries such as Mexico. Among other things, they require tanneries to register with environmental authorities, install sedimentation tanks and water gauges, handle most solid wastes as hazardous materials, and— most important—pretreat wastewater so that daily concentrations of various pollutants do not exceed set standards. For the most part, however, these regulations are simply not enforced.[9]  One of the reasons mentioned for this, cited by Allen Blackman,  is that tanneries are often a mainstay of the local economy and therefore enjoy considerable political power.

So today Hazaribag, Dhaka, home to many leather tanneries,  the  once  pleasant, semi-rural district in the Bangladeshi capital, is now a wasteland of toxic swamps, garbage landfills and mountains of decomposing leather scraps, surrounded by slums where tannery workers live.  Piles of smouldering trash line the banks of the nearby Buriganga, which is classified as a “dead” river after it hits Hazaribag as pollution from the tanneries has made it impossible for any fish or plantlife to survive.

Every day, the tanneries collectively dump 22,000 cubic litres of toxic waste, including cancer-causing chromium, into the Buriganga — Dhaka’s main river and a key water supply — according to the ministry of environment.

More than 90 percent of the 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.[10]

This is The Ecologist Film Unit’s Jim Wickens take on what the situation is in Dhaka:

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.[11]  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.

Groundwater near tanneries has been found with highly elevated levels of a variety of toxic substances. The Regis Tanning Co., Inc., operated a tanning facility from the early 1950s until 1972 in New Hampshire. But more than 20 years after it closed down, groundwater samples collected in the area revealed that arsenic, chromium, lead, and zinc were all still present—likely because of wastes disposed of on the property—while samples taken from nearby Lamprey River and its wetlands indicated the presence of cyanide, chromium, and polychlorinated biphenyls (PCBs).[12]

The U.S. Centers for Disease Control and Prevention (CDC) found that the incidence of leukemia among residents near one tannery in Kentucky was five times the national average.[13]

Arsenic, a common tannery chemical, has long been associated with lung cancer in workers who are exposed to it on a regular basis. Several studies have established links between sinus and lung cancer and the chromium used in tanning. [14] Studies of leather-tannery workers in Sweden and Italy found cancer risks “between 20% and 50% above [those] expected.” [15]

And that aniline dye that is often advertised as non toxic:  not according to these sources:  Aniline is toxic by inhalation of the vapour.   [16] The International Agency for Research on Cancer(IARC) lists it in Group 3  (not classifiable as to its carcinogenicity to humans) due to the limited and contradictory data available.  It is linked to bladder cancer.[17]

What about vegetable-tanning, which is sometimes touted as an environmentally-friendly alternative to chrome-tanning? Vegetable-tanning is actually only different from chrome-based in one way: it uses vegetable dyes rather than, perhaps, aniline dyes, to give the leather a “more subtle, muted colour.”[18]The preparation of the skin for tanning is the same, and though vegetable-tanning eliminates the toxins produced during the process of chrome-tanning, it also has its limits: being stiffer and firmer than chrome-tanned leather, it can be used for saddles, belts,  and leather carving, but often not for shoes, coats, or anything that requires much flexibility. Additionally, when exposed to water and allowed to dry, it can discolour and shrink, becoming brittle.

As mentioned in the first footnote above, there are a few companies that are trying to transform the industry and to educate consumers about leather, such as Organic Leather in California.  They seek to “return reverence to the practice of working with leather…to pay homage to the tribal peoples of our world and to encourage respect for the quality of the animals’ lives, from the way they are raised to the way they die…(and) to make sure that no part of the animal already being harvested goes to waste.  Moreover, we are strongly concerned with the chemicals used in the tanning and dyeing process and their effects on the natural environment and the health of both workers and customers.”


[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] Kate Carter, Don’t Hide from the Truth, Guardian.co.uk, 27 Aug. 2008

[3] Leather Made From different animals, Leather Supreme, May 13, 2008 AND “Animals Abused and Killed for their Skins”, PETA media center, 2010.

[5] Davis, John, “Method for safer leather tanning published by Texas Tech researchers”, Texas Tech Today, November 2007.

[6] Blackman, Allen, “Adoption of Clean Leather-Tanning Technologies in Mexico”, discussion paper, Resources for the Future, August 2005

[8] Jasim Uddin Khan, “Local Tanners Eye Bright Prospect as US, EU Quit Leather Processing,” The Daily Star 20 Dec 2007.

[9] Blackman, Allen, “Adoption of Clean Leather-Tanning Technologies in Mexico”, discussion paper, Resrouces for the Future, August 2005

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

[11] Ibid.

[12] U.S. Environmental Protection Agency, “Regis Tannery,” Waste Site Cleanup and Reuse in New England 9 Aug. 2006.

[13] Richard E. Sclove et al., Community-Based Research in the United States (Amherst: The Loka Institute, 1998) 52.

[14] Richard B. Hayes, “The Carcinogenicity of Metals in Humans,” Cancer Causes and Control 8 (1997): 371-85.

[15] France Labrèche, Occupations and Breast Cancer: Evaluation of Associations Between Breast Cancer and Workplace Exposures (Montréal: McGill University, 1997).

[16] Muir, GD (ed.) 1971, Hazards in the Chemical Laboratory, The Royal Institute of Chemistry, London.

[17] http://www.pathologyoutlines.com/topic/bladderurothelialinvasivegen.html  AND Carreon, Tania, et al, “Increased bladder cancer risk among workers exposed to o-toluidine and aniline: a reanalysis”, Occupational and Environmental Medicine, 2010; 67:348-350

[18] Elizabeth Olsen, Can Leather Be Eco-Friendly…Ever?, Ecouterre, 19 Oct. 2009