Hemp vs. Linen

31 08 2016

We are often asked for 100% hemp fabric in lieu of linen fabrics. We offer hemp and adore it, but it may not be the best eco choice.

Make no mistake – we love hemp, we sell hemp fabrics and we think the re-introduction of hemp as a crop would be a boon for American farmers and consumers.

But hemp that is used to produce hemp fabric via conventional methods – as opposed to GOTS methods – is a far inferior choice to any Global Organic Textile Standard (GOTS) or Oeko-Tex certified fabric. So the overriding difference is not between hemp and any other fiber, but between a certified fabric versus one that is not certified, because certification assures us that the fabric is free of any chemicals that can change your DNA, give you cancer or other dred diseases which can affect you in ways ranging from subtle to profound. The choice of GOTS also assures us that the mill which produced the fabric has water treatment in place, so these chemicals don’t pollute our groundwater – and that the mill pays fair wages to their workers who toil in safe conditions!

Now let’s look at some of the differences between hemp and linen:

First, do not be confused by the difference between the fiber and the cloth woven from that fiber – because the spinning of the yarn and the weaving of the cloth introduces many variables that have nothing to do with the fibers. Both hemp and flax (from which linen is derived) are made from fibers found in the stems of plants, and both are very laborious to produce. The strength and quality of both fibers are highly dependent on seed variety, the conditions during growth, time of harvest and manner of retting and other post-harvest handling.

Retting (or, really, rotting) is the microbial decomposition of the pectins which bind the fibers to the woody inner core of the plant stem. The old system of water or snow retting has given way to chemical retting, which in turn often shortens – which means weakens – the fibers. These short fibers are said to have been “cottonized” since cotton fibers are only about 1.5 inches long.

It’s important to note that there is very little to distinguish flax fibers from hemp fibers – they both have similar properties. Hemp’s fibers so closely resemble flax that a high-power microscope is needed to tell the difference. Without microscopic or chemical examination, the fibers can only be distinguished by the direction in which they twist upon wetting: hemp will rotate counterclockwise; flax, clockwise.

In general, hemp fiber bundles are longer than those of flax.   So the first point of differentiation is this: the length of the fibers. Long fibers translate into inherently more resilient and therefore durable yarns. Hemp fibers vary from 4 to about 7 feet in length, while linen is generally 1.5 to 3 feet in length. Other differences:

  • The color of flax fibers is described as yellowish-buff to gray, and hemp as yellowish-gray to dark brown.
  • Hemp is highly resistant to rotting, mildew, mold and salt water. Linen on the other hand is non-allergenic and insect-repellent.
  • Hemp is the most highly resistant natural fiber to ultraviolet light, so it won’t fade or disintegrate in sunlight. Linen too has excellent resistance to UV rays.
  • Hemp’s elastic recovery is very poor and less than linen; it stretches less than any other natural fiber.

The biggest difference between hemp and linen might be in the agricultural arena.

Hemp grows well without the use of chemicals because it has few serious pest problems, although the degree of immunity to attacking organisms has been greatly exaggerated.  Several insects and fungi specialize exclusively in hemp!  But despite this, the use of pesticides and fungicides are usually unnecessary to get a good yield. Hemp has a fiber yield that averages between 485 – 809 lbs., compared to flax, which averages just 323 – 465 lbs. on the same amount of land.   This yield translates into a high biomass, which can be converted into fuel in the form of clean-burning alcohol.

Farmers claim that hemp is a great rotation crop – it was sometimes grown the year prior to a flax crop because it left the land free of weeds and in good condition.   Hemp, it was said, is good for the soil, aerating and building topsoil. Hemp’s long taproot descends for three feet or more, and these roots anchor and protect the soil from runoff. Moreover, hemp does not exhaust the soil. Additionally, hemp can be grown for many seasons successively without impacting the soil negatively. In fact, this is done sometimes to improve soil tilth and clean the land of weeds.

The price of hemp in the market is far higher than for linen, despite hemp’s yields.   We have no idea why this is so. And finding organic hemp is becoming almost impossible, because hemp is usually grown by subsistence farmers who are loath to pay certification fees.

Yarns, made from the fibers, are graded from ‘A’, the best quality, to below ‘D’.   The number of twists per unit length is often (but not always) an indication of a stronger yarn.   In addition, the yarns can be single or plied – a plied yarn is combined with more than one strand of yarn. Next, the cloth can be woven from grade ‘A’ yarns with a double twist per unit length and double ply into a fabric where the yarns are tightly woven together into cloth. Or not.

But in general, there are many similarities between cloth made from hemp and cloth made from linen:

  • Both linen and hemp become soft and supple through handling, gaining elegance and creating a fluid drape.
  • Both hemp and linen are strong fibers – though most sources say hemp is stronger (by up to 8 times stronger) than linen (even though the real winner is spider silk!), but this point becomes moot due to the variables involved in spinning the fiber into yarn and then weaving into fabric.   The lifespan of hemp is the longest of all the natural fibers.
  • Both hemp and linen wrinkle easily.
  • Both hemp and linen absorb moisture. Hemp’s moisture retention is a bit more (12%) than linen’s (10 – 12%)
  • Both hemp and linen breathe – they release moisture back into the atmosphere and do not retain water.
  • Both hemp and linen are natural insulators: both have hollow fibers which means they’re cool in summer and warm in winter.
  • Both hemp and linen have anti-bacterial properties.
  • Both hemp and linen benefit from washing, becoming softer and more lustrous with each wash.
  • Both hemp and linen are resistant to moths and other insects.
  • Both hemp and linen absorb dyestuffs readily.
  • Both hemp and linen biodegrade.

The overriding difference is not between hemp and linen, but between a hemp OR linen fabric that has GOTS or Oeko-Tex certification and one that does not. That means that a conventional hemp fabric, which enjoys all the benefits of hemp’s attributes, also introduces unwanted chemicals into your life: such as formaldehyde, phthalates, heavy metals, endocrine disruptors and perhaps soil or fire retardants. The certified fabric is the better choice. If the choice is between a conventional hemp fabric and a certified linen fabric, we wouldn’t hesitate a second to choose the linen over the hemp, especially because hemp and linen are such close cousins.








Our response to the Flint water crisis

22 06 2016


An editorial by Nicholas Kristof was published in the February 13, 2016, issue of the New York Times entitled: “Are you a Toxic Waste Disposal Site?” We think Mr. Kristof makes some great points, so we’ve published the entire editorial below:

EVEN if you’re not in Flint, Mich., there are toxic chemicals in your home. For that matter, in you.

Scientists have identified more than 200 industrial chemicals — from pesticides, flame retardants, jet fuel — as well as neurotoxins like lead in the blood or breast milk – of Americans, indeed, in people all over our planet.

These have been linked to cancer, genital deformities, lower sperm count, obesity and diminished I.Q. Medical organizations from the President’s Cancer Panel to the International Federation of Gynecology and Obstetrics have demanded tougher regulations or warned people to avoid them, and the cancer panel has warned that “to a disturbing extent, babies are born ‘pre-polluted.’”

They have all been drowned out by chemical industry lobbyists.

So we have a remarkable state of affairs:

■ Politicians are (belatedly!) condemning the catastrophe of lead poisoning in Flint. But few acknowledge that lead poisoning in many places in America is even worse than in Flint. Kids are more likely to suffer lead poisoning in Pennsylvania or Illinois or even most of New York State than in Flint. More on that later.

■ Americans are panicking about the mosquito-borne Zika virus and the prospect that widespread infection may reach the United States. That’s a legitimate concern, but public health experts say that toxic substances around us seem to pose an even greater threat.

“I cannot imagine that the Zika virus will damage any more than a small fraction of the total number of children who are damaged by lead in deteriorated, poor housing in the United States,” says Dr. Philip Landrigan, a prominent pediatrician and the dean for global health at the Icahn School of Medicine at Mount Sinai. “Lead, mercury, PCBs, flame retardants and pesticides cause prenatal brain damage to tens of thousands of children in this country every year,” he noted.

Yet one measure of our broken political system is that chemical companies, by spending vast sums on lobbying— $100,000 per member of Congress last year — block serious oversight.[1] Almost none of the chemicals in products we use daily have been tested for safety.

Maybe, just maybe, the crisis in Flint can be used to galvanize a public health revolution.

In 1854, a British doctor named John Snow started such a revolution. Thousands were dying of cholera at the time, but doctors were resigned to the idea that all they could do was treat sick patients. Then Snow figured out that a water pump on Broad Street in London was the source of the cholera[2]. The water company furiously rejected that conclusion, but Snow blocked use of the water pump, and the cholera outbreak pretty much ended. This revelation led to the germ theory of disease and to investments in sanitation and clean water. Millions of lives were saved.

Now we need a similar public health revolution focusing on the early roots of many pathologies.

For example, it’s scandalous that 535,000 American children ages 1 to 5 still suffer lead poisoning, according to the Centers for Disease Control and Prevention[3]. The poisoning is mostly a result of chipped lead paint in old houses or of lead-contaminated soil being tracked into homes, although some areas like Flint also have tainted tap water. (Note:  fabrics often contain lead in the dyes used and as a catalyst in the dyeing process.)

lead paint

While the data sets are weak, many parts of America have even higher rates of child lead poisoning than Flint, where 4.9 percent of children tested have had elevated lead levels in their blood. In New York State outside New York City, it’s 6.7 percent. In Pennsylvania, 8.5 percent. In parts of Detroit, it’s 20 percent. The victims are often poor or black.[4]

Infants who absorb lead are more likely to grow up with shrunken brains and diminished I.Q.[5] They are more likely as young adults to engage in risky sexual behavior, to disrupt school and to commit violent crimes. Many researchers believe that the worldwide decline in violent crime beginning in the 1990s is partly a result of lead being taken out of gasoline in the late 1970s. The stakes are enormous, for individual opportunity and for social cohesion.

Fortunately, we have some new Dr. Snows for the 21st century.

A group of scholars, led by David L. Shern of Mental Health America, argues that the world today needs a new public health revolution focused on young children, parallel to the one mounted for sanitation after Snow’s revelations about cholera in 1854. Once again, we have information about how to prevent pathologies, not just treat them — if we will act.

The reason for a new effort is a vast amount of recent research showing that brain development at the beginning of life affects physical and mental health decades later. That means protecting the developing brain from dangerous substances and also from “toxic stress”— often a byproduct of poverty — to prevent high levels of the stress hormone cortisol, which impairs brain development.

A starting point of this public health revolution should be to protect infants and fetuses from toxic substances, which means taking on the companies that buy lawmakers to prevent regulation. Just as water companies tried to obstruct the 19th-century efforts, industry has tried to block recent progress.

Back in 1786, Benjamin Franklin commented extensively on the perils of lead poisoning, but industry ignored the dangers and marketed lead aggressively. In the 1920s, an advertisement for the National Lead Company declared, “Lead helps to guard your health,” praising the use of lead pipes for plumbing and lead paint for homes. And what the lead companies did for decades, and the tobacco companies did, too, the chemical companies do today.


Lead poisoning is just “the tip of the iceberg,” says Tracey Woodruff, an environmental health specialist at the University of California at San Francisco. Flame-retardant chemicals have very similar effects, she says, and they’re in the couches we sit on.

The challenge is that the casualties aren’t obvious, as they are with cholera, but stealthy and long term. These are silent epidemics, so they don’t generate as much public alarm as they should.

“Industrial chemicals that injure the developing brain” have been linked to conditions like autism and attention deficit hyperactivity disorder, noted The Lancet Neurology, a peer-reviewed medical journal. Yet we still don’t have a clear enough sense of what is safe, because many industrial chemicals aren’t safety tested before they are put on the market. Meanwhile, Congress has dragged out efforts to strengthen the Toxic Substances Control Act and test more chemicals for safety.

The President’s Cancer Panel recommended that people eat organic if possible, filter water and avoid microwaving food in plastic containers. All good advice, but that’s like telling people to avoid cholera without providing clean water.

And that’s why we need another public health revolution in the 21st century.


[1] http://www.opensecrets.org/lobby/indusclient.php?id=N13&year=2015

[2] http://www.bbc.co.uk/history/historic_figures/snow_john.shtml

[3] http://www.cdc.gov/mmwr/preview/mmwrhtml/mm6213a3.htm

[4] http://www.nytimes.com/2016/02/07/opinion/sunday/america-is-flint.html

[5] http://journalistsresource.org/studies/society/public-health/lead-poisoning-exposure-health-policy?utm_source=JR-email&utm_medium=email&utm_campaign=JR-email&utm_source=Journalist%27s+Resource&utm_campaign=63b82f94eb-2015_Sept_1_A_B_split3_24_2015&utm_medium=email&utm_term=0_12d86b1d6a-63b82f94eb-79637481

What will nanotechnology mean to you?

2 04 2014

A hot topic in the media right now is the toxicity of chemical flame retardants that are in our furniture and are migrating out into our environment.  Tests have shown that Americans carry much higher levels of these chemicals in their bodies than anyone else in the world, with children in California containing some of the highest levels ever tested.   According to Ronald Hites of Indiana University, these concentrations have been “exponentially increasing, with a doubling time of 4 to 5 years.”[1]  These toxic chemicals are present in nearly every home – packed into couches, chairs and many baby products including (but not limited to) mattresses, nursing pillows, carriers and changing table pads (scary!).  Recent studies have found that most couches in America have over 1 pound of the toxic chemical Chlorinated Tris inside them[2], even though it was banned in children’s pajamas over cancer concerns over a generation ago.[3]

Why the concern?  Fire retardant chemicals, called PBDE’s (polybrominated diphenyl ethers) have been linked to cancer, reproductive problems and impaired fetal brain development, as well as decreased fertility.  And even though they’ve been banned in the U.S. and European Union, they persist in the environment and accumulate in your body – and they’re still being used today.

So its probably no surprise that there is a mad scramble on to produce a fire retardant that does not impact our health or the environment.   The current front runners, touted as being “exceptionally” effective yet safer and more environmentally friendly than the current fire retardants, use nanotechnology – specifically “nanocoatings” and “nanocomposites”[4] .  These composites and coatings are based on what are called “multiwalled carbon nanotubes” or MWCNTs.

Based on a final report published by the U.S. EPA in September 2013 about the assessment of the risks of using these  MWCNTs, the EPA found that there will be releases of these MWCNTs into the environment throughout the life cycle of textiles – to our air and water during production,  in the form of abraded particles of the textiles falling into the dust in our homes, and in the disposal of furniture in municipal landfills or incineration facilities.[5]

While it is reasonable to propose that substituting nanomaterials for polybrominated diphenyl ether (PBDEs)  or chlorinated triss  and calling it “sustainable”, the fact is that no quantitative study has ever been done to support this assertion . [6]

Please don’t misunderstand me – I am all for finding safer alternatives to the current crop of chemical fire retardants (assuming I buy into the argument that we actually need them).  However, I don’t want us to jump from the frying pan into the fire by rushing to use a technology which is still controversial.  But the race is on:  the US patent office published some 4000 patents under “977 – nanotechnology” in 2012, a new record.

patents nanotech

Here’s an interesting video which helps to explain how nano works – and why we will need extensive study to absorb the many implications of this emerging science.

Consider these science fiction type scenarios of how nano can be used to profoundly change our lives:

  • “nanomedicine” offers the promise of diagnosis and treatment of a disease – before you even have the symptoms.  Or it promises to rebuild neurons for people with Alzheimers or Parkinson’s disease – and stem cells for whatever ails you!   Bone regeneration.  [7]
  • Surfaces can be modified to be scratchproof, unwettable, clean or sterile, depending on the application.[8]
  • Quantum computing.
  • Solar cells capturing the sun’s visible spectrum – as well as infrared photons –  doubling the solar energy available to us.  How about zero net carbon emissions.
  • Nanoscale bits of metals can detoxify hazardous wastes.
  • Clothing that recharges your cell phone as you stroll, or an implant that measures blood pressure powered by your own heartbeat.

And yet.  The unknowns are great, and as Eric Drexler has said, the story involves a tangle of science and fiction linked with money, press coverage, Washington politics and sheer confusion.  Scientists and governments agree that the application of nanotechnology to commerce poses important potential risks to human health and the environment, and those risks are unknown. Examples of high level respected reports that express this concern include:

  • Swiss Federation (Precautionary Matrix 2008)[9]
  • Commission on Environmental Pollution (UK 2008)[10];
  • German Governmental Science Commission (“SRU”)[11];
  • Public testimony sought by USA National Institute for Occupational Safety and Health (NIOSH, Feb 2011)[12] ;
  • OECD working group (since 2007)[13];
  • World Trade Organization (WTO)[14]
  • as well as several industrial groups and various non-governmental organizations.

Nanotechnology is already transforming many products – water treatment, pesticides, food packaging and cosmetics to name a few – so the cat is already out of the bag.  Consider this small example of the nano particle  argument:  When ingested the nanoparticles pass into the blood and lymph system, circulate throughout the body and reach potentially sensitive sites such as the spleen, brain, liver and heart.[15]   The ability of nanoparticles to cross the blood brain barrier makes them extremely useful as a way to deliver drugs directly to the brain.  On the other hand, these nanoparticles may be toxic to the brain.  We simply don’t know enough about the size and surface charge of nanoparticles to draw conclusions.[16]  In textiles, silver nano particles are used as antibacterial/antifungal agents to prevent odors.

But there are almost no publications on the effects of engineered nanoparticles on animals and plants in the environment.

So it’s still not clear what nanoscience will grow up to be – if it doesn’t kill us, it might just save us.

[2] Stapleton HM, et al. Detection of organophosphate flame retardants in furniture foam and U.S. house dust. Environ Sci Technol 43(19):7490–7495. (2009); http://dx.doi.org/10.1021/es9014019.

[3] Callahan, P and Hawthorne, M; “Chemicals in the Crib”, Chicago Tribune, December 28, 2012, http://articles.chicagotribune.com/2012-12-28/news/ct-met-flames-test-mattress-20121228_1_tdcpp-heather-stapleton-chlorinated-tris

[5] Comprehensive Environmental Assessment Applied to Multiwalled Carbon Nanotube Flame-Retardant Coatings in Upholstery Textiles: A Case Study Presenting Priority Research Gaps for Future Risk Assessments (Final Report), Environmental Protection Agency, http://cfpub.epa.gov/ncea/nano/recordisplay.cfm?deid=253010

[6] Gilman,  Jeffrey W., “Sustainable Flame Retardant Nanocomposites”; National Institute of Standards and Technology

[7] Hunziker, Patrick,  “Nanomedicine: The Use of Nano-Scale Science for the Benefit of the Patient” European Foundation for Clinical Nanomedicine (CLINAM) Basel, Switzerland 2010.

[9] Swiss National Science Foundation, Opportunities and Risks of Nanomaterials Implementation Plan of the National Research Programme NRP 64 Berne, 6 October 2009; see also Swiss Precautionary Matrix, and documents explaining and justifying its use, available in English from the Federal Office of Public Health.

[10] Chairman: Sir John Lawton CBE, FRS Royal Commission on Environmental Pollution, Twenty-seventh report: Novel Materials in the Environment: The case of nanotechnology. Presented to Parliament by Command of Her Majesty November 2008.

[11] SRU, German Advisory Council on Environment, Special Report “Precautionary strategies for managing nanomaterials” Sept 2011. The German Advisory Council on the Environment (SRU) is empowered by the German government to make “recommendations for a responsible and precautionary development of this new technology”.

[12] See: Legal basis and justification: Niosh recommendations preventing risk from carbon nanotubes and nanofibers ”post-hearing comments Niosh current intelligence bulletin: occupational exposure to carbon nanotubes and nanofibers Docket NO. NIOSH-161 Revised 18 February 2011; Testimony on behalf of ISRA (International Safety Resources Association) Before NIOSH, USA. Comments prepared by Ilise L Feitshans JD and ScM, Geneva, Switzerland. Testimony presented by Jay Feitshans, Science Policy Analyst; ISRA Draft Document for Public Review and Comment NIOSH Current Intelligence Bulletin: Occupational Exposure to Carbon Nanotubes and Nanofibers, Docket Number NIOSH-161-A.

[13] The OECD Working Party for Manufactured Nanomaterials (WPMN) “OECD Emission Assessment for Identification of Sources of release of Airborne Manufactured Nanomaterials in the Workplace: Compilation of Existing Guidance”, ENV/JM/MONO (2009)16, http://www.oecd.org/dataoecd/15/60/43289645.pdf. “OECD Preliminary Analysis of Exposure Measurement and Exposure Mitigation in Occupational Settings: Manufactured Nanomaterials” OECD ENV/JM/MONO(2009)6, 2009. http://www.oecd.org/dataoecd/36/36/42594202.pdf.
“OECD Comparison of Guidance on selection of skin protective equipment and respirators for use in the workplace: manufactured nanomaterials”, OECD ENV/JM/MONO(2009) 17, 2009. www.oecd.org/dataoecd/15/56/43289781.pdf.

[14] WHO Guidelines on “Protecting Workers from Potential Risks of Manufactured Nanomaterials” (WHO/NANOH), (Background paper) 2011

[15] Dixon, D., “Toxic nanoparticles might be entering human food supply, MU study finds”, August 22, 2013, http://munews.missouri.edu/news-releases/2013/0822-toxic-nanoparticles-might-be-entering-human-food-supply-mu-study-finds/

[16] Scientific Committee on Emerging and Newly Identified health Risks (SCENIHR), The European Commission, 2006



How to avoid toxins in fabrics – and other products

6 12 2013

In response to a post a few weeks back, Susan Lanham wrote to us:  “I initially signed on to get this blog because I thought you would give practical ways to avoid these carcinogens. However, they are so pervasive, and there doesn’t seem to be any practical way to avoid them, so that reading your blog just makes me feel helpless and hopeless. More and more I just delete without reading: it’s like diagnosing a disease early when there is nothing to be done for it.”

Yikes.  We certainly didn’t want to turn people off in despair!  There is much you can do armed with a bit of knowledge.

We have always thought that information is the great motivator – that if people knew what they were buying, then they would demand changes in those products.  Remember that each time you purchase something,  you’re ensuring that the product you bought will keep being produced, in the same  way.  If you support new ideas, find that creative way to use something or insist that what you buy meets certain parameters, then new research will be done to meet consumer demand and new processes will be developed that don’t leave a legacy of destruction.

At least in theory, right?

The reality is that change takes a long time, and we’re living in a toxic soup now – so what can we do to protect ourselves right now?

And after all, just because almost anything can kill you doesn’t mean fabrics should.  So here’s my list of things you can do to begin to protect yourself from toxins in fabrics:

  1. Buy only GOTS or Oeko Tex certified fabrics if you can  – for everything, not just sheets and pajamas – starting now.   If you can’t find GOTS or Oeko Tex certified fabrics, try to use 100% organic natural fibers.  Certifications are a shorthand which allows us to accept that the certified products are safe, but if you want to get granular, you can find out what they’re certifying (i.e., what the certifications are telling you).  Be sure to differentiate between, for example, a GOTS certified fiber and a GOTS certified fabric.  Big difference:  A product which uses GOTS certified fibers only may have been processed conventionally, which means it could be full of chemicals of concern.
  2. If it’s cheap, it probably has hidden costs, like your health or our ecosystem.  It’s expensive to go against the flow, and natural fibers cost way more than synthetics, even though the price of crude is going up.  So pay more, use less.
  3. Never buy anything made of PVC (polyvinyl chloride) or acrylic (which can be used as finishes or backings as well as fibers) and generally avoid other synthetics (such as polyester).  They ALL start with toxic inputs (like ethylene glycol), but the profiles of both PVC and acrylic makes polyester look benign by comparison.  In that same vein, avoid fabrics that are pretending to be something they’re not – polyester can be made to look like practically anything (one of the things we love about it), but it won’t have the characteristics of the natural fibers that make them such good choices for us.
  4. If you must use synthetic fibers, the best choice would be GRS Gold level recycled polyester.  This new certification means that the recycled content really is  95-100%, with the added assurance that chemicals used in the manufacture abide by the GOTS standards (eliminating endocrine disrupting chemicals, heavy metals, and a long list of other chemicals of concern); water is treated and workers are given minimal rights.
  5. Never buy wrinkle-free or permanent-press anything and pass on any stain protection treatments. The wrinkle free finishes are formaldehyde resins, and there simply are no safe stain protection treatments.
  6. Fly less.  (I never said these would be easy, but it’s good to know, right?)  In this case my issue is not with the carbon footprint (which is tremendous) but because the fabrics are so drenched in flame retardants that people who fly often have elevated levels of PBDEs in their blood – and you already know that PBDEs and their ilk are to be avoided as much as possible.  Same is true of fabrics on cruise ships.
  7. Trust your nose.  If a fabric stinks, what does that tell you about it?
  8. Ask questions!  If they can’t tell you what’s in it, you probably don’t want to live with it.
  9. Get involved and become informed! Force the federal government to fulfill its obligation to protect us from harm – join something (like a Stroller Brigade, sponsored by Safer Chemicals, Healthy Families or Washington Toxics Coalition, for example) and urge your representatives to support the Safe Chemicals Act.  And share what you’ve learned.  This is an evolving industry, and we’re all looking for answers. But I know you’re just ONE person – and the problems do seem overwhelming.  Can just ONE person change the world? Margaret Meade said that committed people, banding together, is the only thing that ever has.
  10. Be aware of greenwashing.  This doesn’t mean waiting for the perfect product but it does mean honesty in letting you (the consumer) know exactly what is in the fabric.  If you see a green claim, Google the company name + environment and see what pops up.  If it’s a big company, do they spend a significant portion of their R&D budget on green initiatives?  What percent of their product offerings are “green” vs. “conventional”?

That does it for fabrics, but here are a few more things you can do to protect yourself :

  • Take off your shoes in the house – simple and easy, and it prevents lots of pesticides and other chemicals from being tracked in.
  • Vacuum and/or dust regularly –because the dust in our homes has been proven to contain lots of chemicals – wafted there from the other products in our homes.
  • Filter your water. You’d be surprised to read the list of really bad chemicals found in most tapwater in the United States – if you’re interested, read the series called “Toxic Waters” which was published in the New York Times.
  • Avoid polyurethane (i.e., poly foam, found in cushions and many other products) if you’re in the market for a new sofa or mattress, look for 100% natural – and certified – latex.
  • Read the labels of your grooming products – avoid anything that includes the words “paraben” (often used as a suffix, as in methylparaben) or “phthalate” (listed as dibutyl and diethylhexyl or just “fragrance”). If there isn’t an ingredients list, log on to cosmeticsdatabase.com, a Web site devised by the Environmental Working Group that identifies the toxic ingredients of thousands of personal-care products.
  • About plastics: Never use plastics in the microwave. Avoid “bad plastics” like PVC and anything with “vinyl” in its name. And don’t eat microwave popcorn, because the inside of a microwave popcorn bag is usually coated with a chemical that can migrate into the food when heated. It has been linked to cancer and birth defects in animals.
  • As Michael Pollan says: “Eat food. Not too much. Mostly plants.” I’d add: eat organic as much as possible, support local farmers and don’t eat meat and fish every day. Grow an organic garden – one of the most powerful things you can do! If you can only purchase a few organic foods, there are lots of lists that tell you which are the most pesticide-laden.
  • Replace cleaning products with non toxic alternatives – either commercially available cleaning products (avoiding ammonia, artificial dyes, detergents, aerosol propellants, sodium hypochlorite, lye, fluorescent brighteners, chlorine or artificial fragrances) or homemade. You probably can do most cleaning with a few simple ingredients like baking soda, lemon juice and distilled white vinegar. Lots of web sites offer recipes for different cleaners – I like essential oils (such as lavender, lemongrass, sweet orange, peppermint, cedar wood and ylang-ylang) in a bucket of soap and hot water. It can clean most floors and surfaces and it won’t kill me.
  • And now that we mention it, avoid using any product which lists “fragrance” as an ingredient.

I know that even that is a daunting list – it’s really hard to avoid some products and growing an organic garden just isn’t in the cards for some of us.  But if you do even some of these things your health – and ours! – will benefit.  Not to mention all the living things on Earth which depend on our good stewardship of this planet.

Fabric and your carbon footprint

3 10 2013

In considering fabric for your sofa, let’s be altruistic and look at the impact textile production has on global climate change.  (I only use the term altruistic  because many of us don’t equate climate change with our own lives, though there have been several interesting studies of just how the changes will impact us directly, like the one in USA Today that explains that wet regions will be wetter, causing flash flooding;  dry regions will get drier, resulting in drought. And  …  a heat wave that used to occur once every 100 years now happens every five years (1)).

Bill Schorr

Bill Schorr

Although most of the current focus on lightening our carbon footprint revolves around transportation and heating issues, the modest little fabric all around you turns out to be from an industry with a gigantic carbon footprint. The textile industry, according to the U.S. Energy Information Administration, is the 5th largest contributor to CO2 emissions in the United States, after primary metals, nonmetallic mineral products, petroleum and chemicals.[2]  And the US textile industry is small potatoes when compared with some other countries I could mention.  Last week we explained that a typical “quality” sofa  uses about 20 yards of decorative fabric, plus 20 yds of lining fabric, 15 yds of burlap and 10 yds of muslin, for a total of 65 yards of fabric – in one sofa.

The textile industry is huge, and it is a huge producer of greenhouse gasses.  Today’s textile industry is one of the largest sources of greenhouse gasses (GHG’s) on Earth, due to its huge size.[3] In 2008,  annual global textile production was estimated at  60 billion kilograms (KG) of fabric.  The estimated energy and water needed to produce that amount of fabric boggles the mind:

  • 1,074 billion kWh of  electricity  or 132 million metric tons of coal and
  • between 6 – 9  trillion liters of water[4]

Fabrics are the elephant in the room.  They’re all around us  but no one is thinking about them.  We simply overlook fabrics, maybe because they are almost always used as a component in a final product that seems rather innocuous:  sheets, blankets, sofas, curtains, and of course clothing.  Textiles, including clothing,  accounted for about one ton of the 19.8 tons of total CO2 emissions produced by each person in the U.S. in 2006. [5] By contrast, a person in Haiti produced a total of only 0.21 tons of total carbon emissions in 2006.[6]

Your textile choices do make a difference, so it’s vitally important to look beyond thread counts, color and abrasion results.

How do you evaluate the carbon footprint in any fabric?  Look at the “embodied energy’ in the fabric – that is, all of the energy used at each step of the process needed to create that fabric.   Not an easy thing to do!  To estimate the embodied energy in any fabric it’s necessary to add the energy required in two separate fabric production steps:

(1)  Find out what the fabric is made from, because the type of fiber tells you a lot about the energy needed to make the fibers used in the yarn.  The carbon footprint of various fibers varies a lot, so start with the energy required to produce the fiber.

(2) Next, add the energy used to weave those yarns into fabric.  Once any material becomes a “yarn” or “filament”, the amount of energy and conversion process to weave that yarn into a textile is pretty consistent, whether the yarn is wool, cotton,  or synthetic.[7]

Let’s look at #1 first: the energy needed to make the fibers and create the yarn. For ease of comparison we’ll divide the fiber types into “natural” (from plants, animals and less commonly, minerals) and “synthetic” (man made).

For natural fibers you must look at field preparation, planting and field operations (mechanized irrigation, weed control, pest control and fertilizers (manure vs. synthetic chemicals)), harvesting and yields.  Synthetic fertilizer use is a major component of the high cost of conventional agriculture:  making just one ton of nitrogen fertilizer emits nearly 7 tons of CO2 equivalent greenhouse gases.

For synthetics, a crucial fact is that the fibers are made from fossil fuels.   Very high amounts of energy are used in extracting the oil from the ground as well as in the production of the polymers.

A study done by the Stockholm Environment Institute on behalf of the BioRegional Development Group  concludes that the energy used (and therefore the CO2 emitted) to create 1 ton of spun fiber is much higher for synthetics than for hemp or cotton:

KG of CO2 emissions per ton of spun   fiber:
crop cultivation fiber production TOTAL
polyester USA 0.00 9.52 9.52
cotton, conventional, USA 4.20 1.70 5.90
hemp, conventional 1.90 2.15 4.05
cotton, organic, India 2.00 1.80 3.80
cotton, organic, USA 0.90 1.45 2.35

The table above only gives results for polyester; other synthetics have more of an impact:  acrylic is 30% more energy intensive in its production than polyester [8] and nylon is even higher than that.

Not only is the quantity of GHG emissions of concern regarding synthetics, so too are the kinds of gasses produced during production of synthetic fibers.  Nylon, for example, creates emissions of N2O, which is 300 times more damaging than CO2 [9] and which, because of its long life (120 years) can reach the upper atmosphere and deplete the layer of stratospheric ozone, which is an important filter of UV radiation.  In fact, during the 1990s, N2O emissions from a single nylon plant in the UK were thought to have a global warming impact equivalent to more than 3% of the UK’s entire CO2 emissions.[10] A study done for the New Zealand Merino Wool Association shows how much less total energy is required for the production of natural fibers than synthetics:

Embodied   Energy used in production of various fibers:
energy use in   MJ per KG of fiber:
flax fibre   (MAT) 10
cotton 55
wool 63
Viscose 100
Polypropylene 115
Polyester 125
acrylic 175
Nylon 250

SOURCE:  “LCA: New Zealand Merino Wool Total Energy Use”, Barber and Pellow,      http://www.tech.plym.ac.uk/sme/mats324/mats324A9%20NFETE.htm

Natural fibers, in addition to having a smaller carbon footprint in the production of the spun fiber, have many additional  benefits:

  1. being able to be degraded by micro-organisms and composted (improving soil structure); in  this way the fixed CO2 in the fiber will be released and the cycle closed.   Synthetics do not decompose: in landfills they release  heavy metals and other additives into soil and groundwater.       Recycling requires costly separation, while incineration produces  pollutants – in the case of high density polyethylene, 3 tons of CO2 emissions are produced for ever 1 ton of material burnt.[11] Left in the environment, synthetic fibers contribute, for example, to the estimated 640,000 tons of abandoned  fishing nets in the world’s oceans.
  2. sequestering  carbon.  Sequestering carbon is the process through which CO2 from the atmosphere is absorbed by plants through photosynthesis and stored as carbon in biomass (leaves, stems, branches, roots, etc.) and soils.       Jute, for example, absorbs 2.4 tons of carbon per ton of dry fiber.[12]

Substituting organic fibers for conventionally grown fibers is not just a little better – but lots better in all respects:

  • uses less energy for production,
  • emits fewer greenhouse gases
  • and supports organic farming (which has myriad environmental, social and health benefits).

A study published by Innovations Agronomiques (2009) found that 43% less GHG are emitted per unit area under organic agriculture than under conventional agriculture.[13] A study done by Dr. David Pimentel of Cornell University found that organic farming systems used just 63% of the energy required by conventional farming systems, largely because of the massive amounts of energy requirements needed to synthesize nitrogen fertilizers. Further it was found in controlled long term trials that organic farming adds between 100-400kg of carbon per hectare to the soil each year, compared to non-organic farming.  When this stored carbon is included in the carbon footprint, it reduces the total GHG even further.[14] The key lies in the handling of organic matter (OM): because soil organic matter is primarily carbon, increases in soil OM levels will be directly correlated with carbon sequestration. While conventional farming typically depletes soil OM, organic farming builds it through the use of composted animal manures and cover crops.

Taking it one step further beyond the energy inputs we’re looking at, which help to mitigate climate change, organic farming helps to ensure other environmental and social goals:

  • eliminates the use of synthetic fertilizers, pesticides and genetically modified organisims      (GMOs) which is  an improvement in human health and agrobiodiversity
  • conserves water  (making the soil more friable so rainwater is absorbed better – lessening      irrigation requirements and erosion)
  • ensures sustained  biodiversity
  • and compared to forests, agricultural soils may be a more secure sink for atmospheric      carbon, since they are not vulnerable to logging and wildfire.

Organic agriculture is an undervalued and underestimated climate change tool that could be one of the most powerful strategies in the fight against global warming, according to Paul Hepperly, Rodale Institute Research Manager. The Rodale Institute Farming Systems Trial (FST) soil carbon data (which covers 30 years)  provides convincing evidence that improved global terrestrial stewardship–specifically including regenerative organic agricultural practices–can be the most effective currently available strategy for mitigating CO2 emissions.

At the fiber level it is clear that synthetics have a much bigger footprint than does any natural fiber, including wool or conventionally produced cotton.   So in terms of the carbon footprint at the fiber level, any natural fiber beats any synthetic – at this point in time.   Best of all is an organic natural fiber.

And next let’s look at #2, the energy needed to weave those yarns into fabric.

There is no dramatic difference in the amount of energy needed to weave fibers into fabric depending on fiber type.[15] The processing is generally the same whether the fiber is nylon, cotton, hemp, wool or polyester:   thermal energy required per meter of cloth is 4,500-5,500 Kcal and electrical energy required per meter of cloth is 0.45-0.55 kwh. [16] This translates into huge quantities of fossil fuels  –  both to create energy directly needed to power the mills, produce heat and steam, and power air conditioners, as well as indirectly to create the many chemicals used in production.  In addition, the textile industry has one of the lowest efficiencies in energy utilization because it is largely antiquated.

(1)    http://www.usatoday.com/story/news/nation/2013/02/28/climate-change-remaking-america/1917169/

(2)    Source: Energy Information Administration, Form EIA:848, “2002 Manufacturing Energy Consumption Survey,” Form EIA-810, “Monthly Refinery Report” (for 2002) and Documentatioin for Emissions of Greenhouse Gases in the United States 2003 (May 2005). http://www.eia.doe.gov/emeu/aer/txt/ptb1204.html

(3)    Dev, Vivek, “Carbon Footprint of Textiles”, April 3, 2009, http://www.domain-b.com/environment/20090403_carbon_footprint.html

(4)    Rupp, Jurg, “Ecology and Economy in Textile Finishing”,  Textile World,  Nov/Dec 2008

(5)    Rose, Coral, “CO2 Comes Out of the Closet”,  GreenBiz.com, September 24, 2007

(6)     U.S. Energy Information Administration, “International Energy Annual 2006”, posted Dec 8, 2008.

(7)    Many discussions of energy used to produce fabrics or final products made from fabrics (such as clothing) take the “use” phase of the article into consideration when evaluating the carbon footprint.  The argument goes that laundering the blouse (or whatever) adds considerably to the final energy tally for natural fibers, while synthetics don’t need as much water to wash nor as many launderings.  We do not take this component into consideration because

  1. it applies only to clothing; even sheets aren’t washed as often as clothing while upholstery is seldom cleaned.
  2. is biodegradeable detergent used?
  3. Is the washing machine used a new low water machine?  Is the water treated by a municipal facility?
  4. Synthetics begin to smell if not treated with antimicrobials, raising the energy score.

Indeed, it’s important to evaluate the sponsors of any published studies, because the studies done which evaluate the energy used to manufacture fabrics are often sponsored by organizations which might have an interest in the outcome.  Additionally, the data varies quite a bit so we have adopted the values which seem to be agreed upon by most studies.

(8)     Ibid.

(9)    “Tesco carbon footprint study confirms organic farming is energy efficient, but excludes key climate benefit of organic farming, soil carbon”, Prism Webcast News, April 30, 2008, http://prismwebcastnews.com/2008/04/30/tesco-carbon-footprint-study-confirms-organic-farming%E2%80%99s-energy-efficiency-but-excludes-key-climate-benefit-of-organic-farming-%E2%80%93-soil-carbon/

(10)  Fletcher, Kate, Sustainable Fashion and Textiles,  Earthscan, 2008,  Page 13

(11) “Why Natural Fibers”, FAO, 2009: http://www.naturalfibres2009.org/en/iynf/sustainable.html

(12)  Ibid.

(13) Aubert, C. et al.,  (2009) Organic farming and climate change: major conclusions of the Clermont-Ferrand seminar (2008) [Agriculture biologique et changement climatique : principales conclusions du colloque de Clermont-Ferrand (2008)]. Carrefours de l’Innovation Agronomique 4. Online at <http://www.inra.fr/ciag/revue_innovations_agronomiques/volume_4_janvier_2009>

(14) International Trade Centre UNCTAD/WTO and Research Institute of Organic Agriculture (FiBL);    Organic Farming and Climate Change; Geneva: ITC, 2007.

(15) 24th session of the FAO Committee on Commodity Problems IGG on Hard Fibers of the United Nations

(16)  “Improving profits with energy-efficiency enhancements”, December 2008,  Journal for Asia on Textile and Apparel,  http://textile.2456.com/eng/epub/n_details.asp?epubiid=4&id=3296

What kind of fabric for your new sofa?

26 09 2013

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, and then 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 yds of lining fabric, 15 yds of burlap and 10 yds 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, a 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: https://oecotextiles.wordpress.com/2010/09/08/is-ultrasuede%c2%ae-a-green-fabric/.

Equally important in evaluating durability as the weight of the fabric 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, even one identified as an upholstery 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
General contract 15,000 20,000
Heavy duty contract 30,000 40,000

According to the Association for Contract Textiles, end use examples of “heavy duty contract” where 30,000 WZ results should be appropriate are single shift corporate offices, hotel rooms, conference rooms and dining areas.  Areas which would require higher than 30,000 WZ are: 24 hour facilities (like transportation terminals, healthcare emergency rooms, casino gambling areas,  and telemarketing offices) and theatres, stadiums, lecture halls and fast food restaurants.

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:

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.”

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.


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.

What does “mercerized” cotton mean?

5 12 2012

fullsizeMercerization is a process applied to cellulosic  fibers  – typically cotton (or cotton-covered thread with a polyester core)  but hemp and linen can be mercerized also – to increase luster.  It is done after weaving (in the case of fabrics) or spinning (for yarns or threads).  But early on it was found that the process also had secondary benefits:  the mercerized fibers were able to absorb more water, and therefore absorb more dye, making the color of the dyed cloth brighter and deeper.  The difference is dramatic:  mercerization increases the absorption of dyestuffs by as much as 25%.[1]  unmercerized-101mercerized-101Not only is the color brighter, it also gives the cloth a better resistance to multiple washings,  keeping the colors bright and unchanged over time.   In addition to increasing luster and affinity to dyestuffs, the  treatment increases strength, smoothness, resistance to mildew, and also reduces lint.  So higher quality yarns and fabrics,  for example, are always mercerized.

The process goes back to the 1880’s.   John Mercer was granted a British Patent for his discovery that cotton and other fibers changed character when subjected to caustic soda (NaOh, also known as sodium hydroxide or lye), sulfuric acid, and/or other chemicals.   One of the changes was that caustic soda caused the fiber to swell, become round and straighten out.  But so what – these changes didn’t impart any luster to the fibers, so his patent was largely ignored.  Then in 1890 Horace Lowe found that by applying Mercer’s caustic soda process to cotton yarn or fabric under tension, the fabric gained a  high luster  as a result of the light reflection off the smooth, round surface created by the NaOH. It became an overnight success and revolutionized the cotton industry. The rest is history.[2]

Later testing proved that cotton fiber in its roving state (no twist in the yarns) would absorb more NaOH than fiber in a twisted state and as a result would absorb more water or dye.  Since fine, long stapled fiber gives the best absorption with the lowest twist, ( some twist is required for treating under tension to gain luster) it is usually the long fiber types of cotton (Sea Island, Egyptian, Pima) that are selected for yarn to be mercerized.   So mercerized cotton fabric starts with a better quality cotton fiber.

How is it done?

To get the desired luster and tensile strength,  cotton is held under specified tension for about ten minutes with an application of between 21%-23% caustic soda (NaOH) and wetting agents (used to facilitate the transfer of the NaOH into the fibers), at room temperature.  Then the fabric is neutralized in an acid bath.

Luster is a result of light reflection off a surface. The more glass like the surface, the better the luster. Yarn in its spun, treated state still has a very fine covering of tiny fiber ends (fuzz). This fuzz is removed by passing the yarn (or fabric) through a controlled heated atmosphere termed singeing (gas fired in the past, electric more currently) resulting in a cleaner surface.  (Luster is a result of light reflection off a surface. The more glass like the surface, the better the luster.)
You knew I’d have to look at the toxicity profile of sodium hydroxide, which is considered one of the building blocks of chemistry.  It’s a very powerful alkali.   It’s used in industry in a broad range of categories: chemical manufacturing; pulp and paper manufacturing; cleaning products such as drains, pipe lines and oven cleaners ; petroleum and natural gas; cellulose film;  and water treatment as well as textiles. The US Food and Drug Administration (FDA) considers sodium hydroxide to be generally safe, and recognizes it as not being found to pose unacceptable dietary risks, though it is generally only used on food contact surfaces rather than in foodstuffs.

The chemical is toxic to wildlife, and the EPA requires that effluent containing NaOH not be discharged into groundwater.  Because sodium hydroxide falls in the group of chemicals (salts) which are by far the most often used in textile processing, the sheer volume of NaOH used by the textile industry is important to recognize.  Usual salt concentrations in cotton mill wastewater can be 2,000 – 3,000 ppm[3], far in excess of Federal guidelines for in-stream salt concentrations of 230 ppm.  So treatment of effluent is very important, as prevention is the only reasonable alternative to solve the environmental problems associated with this hard-to-treat, high volume waste.  I have read that electrochemical cell treatment might be a substitute for using NaOH to mercerize.  This process occurs in a low voltage electrochemical cell that mercerizes, sours, and optionally bleaches without effluents and without the purchase of bulk caustic, neutralizing acids, or bleaches.