Optical brighteners

14 07 2010

I got a call awhile ago from Harmony Susalla, founder and chief designer for Harmony Art  (if you haven’t seen her glorious fabrics go right now to www.harmonyart.com).  She was wondering about optical brighteners, and I discovered I couldn’t tell her much except to say that some are derived from benzene, which is a chemical nobody wants to live with.  GOTS allows the use of optical brighteners – with caveats (see below) – but they are supposed to reevaluate them “in two years from date of adoption” of version 2.0, which puts the reevaluation right about now.

So let’s explore optical brighteners, which are used extensively in:

  • Laundry detergents (to replace whitening agents removed during washing and to make the clothes appear cleaner.) – detergents may contain up to 0.2% whitening agents,
  • Paper, especially high brightness papers, resulting in their strongly fluorescent appearance under UV illumination. Paper brightness is typically measured at 457nm, well within the fluorescent activity range of brighteners. Paper used for banknotes does not contain optical brighteners, so a common method for detecting counterfeit notes is to check for fluorescence.
  • Cosmetics: One application is in formulas for washing and conditioning grey or blonde hair, where the brightener can not only increase the luminance and sparkle of the hair, but can also correct dull, yellowish discoloration without darkening the hair).  Some advanced face and eye powders contain optical brightener microspheres that brighten shadowed or dark areas of the skin, such as “tired eyes”.
  • as well as fabrics, which may contain 0.5% OBAs. A side effect of textile optical whitening is to make the treated fabrics more visible with Night Vision Devices than non-treated ones (the fluorescence caused by optical brighteners can easily be seen with an ordinary black light). This may or may not be desirable for military or other applications

You can still buy “bluing” – which is advertised to “whiten whites and brighten colors”.  Bluing works by removing yellow light to lessen the yellow tinge.   Optical brighteners – also called optical brightening agents (OBAs), fluorescent brightening agents (FBAs), and/or fluorescent whitening agents (FWAs) or “synthetic fluorescent dyes” –  work a bit differently.  Optical brighteners are chemicals similar to dyes which absorb ultraviolet light and emit it back as visible blue light – in other words, they fluoresce the ultraviolet light into visible light. The blue light emitted by the brightener compensates for the diminished blue of the treated material and changes the hue away from yellow or brown and toward white.

They are designed to mask yellow or brown tones in the fibers and make the fabric look cleaner and brighter than it would otherwise appear to the naked eye.   In other words, the undesirable color is made invisible to the eye in an “optical manner”.  Optical brighteners are used both on natural fibers (cotton, linen, hemp, silk) as well as in polymer melts for polyester and other synthetic fiber production.

Optical brighteners aren’t effective unless they remain in the fabric, and persist after washing.  They only last so long, until the point when they actually burn out and no longer do anything. They are also subject to fading when exposed long term to UV.

Brighteners can be “boosted” by the addition of certain polyols like high molecular weight polyethylene glycol or polyvinyl alcohol. These additives increase the visible blue light emissions significantly. Brighteners can also be “quenched”. Too much use of brightener will often cause a greening effect as emissions start to show above the blue region in the visible spectrum.

Optical brighteners are synthesized from various chemicals.  The group of chemicals which are called “optical brighteners” consists of approximately 400 different types listed in the Color Index, but less than 90 are produced commercially. (To get more information about the Color Index click here .)

Basic classes of chemicals used in OBAs  include:

  • Triazine-stilbenes (di-, tetra- or hexa-sulfonated)
  • Coumarins
  • Imidazolines
  • Diazoles
  • Triazoles
  • Benzoxazolines
  • Biphenyl-stilbenes

Using these chemicals, many companies compose their own chemical versions of an optical brightener, and sell it under a branded name, such as:

  • Blankophar R
  • Calcofluor
  • Uvitex
  • Bluton
  • CBS
  • DMS E=416
  • Kolorcron 2B

To find out what is in the optical brightener in any fabric, you must know the name of the optical brightener, and also the C.I. number (such as Brightener 24 or 220).  Then you can look up the chemical composition of the substance – but  only if you’re a subscriber to the Color Index database.  So it’s pretty difficult to confirm what is actually in an optical brightener.

In exploring some of the chemicals used in formulating optical brighteners,  I found one called cyanuric chloride, a derivative of 1,3,5 triazine.  Cyanuric chloride is used as a precursor and crosslinking agent in sulfonated triazine-stilbene based optical brighterners.   It is also classified as “very toxic”, “harmful” and “corrosive” by the EU and has several risk phrases identified with it – including R26 (“very toxic by inhalation”).  R26 is a substance which is specifically prohibited by GOTS.  So how can optical brighteners be allowed under GOTS?

The short answer is:  some are allowed, some are not – it depends on the chemical composition of each individual optical brightener.   Like dyestuffs, GOTS allows optical brighteners if they “meet all criteria for the selection of dyes and auxiliaries as defined in chapter 2.4.6, Dyeing.”  Those criteria include the prohibition of all chemicals listed in 2.3.1 and substances which are assigned certain risk phrases “or combinations thereof”.   But in order to know if a particular optical brightener meets these criteria, it’s necessary to know the chemical formula for that brightener.   And that takes a bit of detective work – and even so you might not be able to get final answers.  Don’t you begin to feel like a hamster in one of those wheels going round and round?

What are the problems associated with optical brighteners?
Some brighteners have been proven to cause allergic skin reactions or eye irritation in sensitive people.   The German Textiles Working Group conducted a health assessment of various optical brightening agents  following concerns of potential health risks to the public. It was found that there is a general lack of information on toxicity and a need for studies into dermal  absorption and the release of these substances from clothes.  While it has not been shown to negatively affect health, it has also not been proven safe.

They are known to be toxic to fish and other animal and plant life and have been found to cause mutations in bacteria.

Most OBAs are not readily biodegradable, so chemicals remain in wastewater for long periods of time, negatively affecting water quality and animal and plant life.  It is assumed that the substances accumulate in sediment or sludge, leading to high concentrations.
In wastewater, OBAs can also leach into groundwater, streams, and lakes. Since fluorescence is easy to detect,  optical brightener monitoring is an emerging technique to quickly and cost-effectivley detect the contamination of stormwater by sanitary wastewater.

REACH is the new European Union regulation which aims to  improve human health and the environment through better and earlier identification of the properties of chemical substances.  REACH stands for Registration, Evaluation, Authorisation and Restriction of Chemical substances.   REACH contains provisions to reduce the use of what are called “high volume production” chemicals.  These are defined as chemicals having annual production and/or importation volumes above 1 million pounds.  It is assumed that high volume production is a proxy for high exposure; in addition, large releases of low toxicity substances such as salts do cause environmental harm due to the sheer volume of the substance.
Much of the impact from optical brighteners comes in the form of large releases of low toxicity substances.  A number of these optical brighteners are listed as high and low production volume substances and so will be subject to REACH.   For example, C.I. Fluorescent Brightener 220 is listed as a high production volume chemical.


Why is recycled polyester considered a sustainable textile?

14 07 2009



Synthetic fibers are the most popular fibers in the world – it’s estimated that synthetics account for about 65% of world production versus 35% for natural fibers.[1] Most synthetic fibers (approximately 70%) are made from polyester, and the polyester most often used in textiles is polyethylene terephthalate (PET).   Used in a fabric, it’s most often referred to as “polyester” or “poly”.

The majority of the world’s PET production – about 60% – is used to make fibers for textiles; about 30% is used to make bottles.   It’s estimated that it takes about 104 million barrels of oil for PET production each year – that’s 70 million barrels just to produce the virgin polyester used in fabrics.[2] That means most polyester – 70 million barrels worth –  is manufactured specifically to be made into fibers, NOT bottles, as many people think.  Of the 30% of PET which is used to make bottles, only a tiny fraction is recycled into fibers.  But the idea of using recycled bottles – “diverting waste from landfills” – and turning it into fibers has caught the public’s imagination.

The reason recycled polyester (often written rPET) is considered a green option in textiles today is twofold, and the argument goes like this:

  1. energy needed to make the rPET is less than what was needed to make the virgin polyester in the first place, so we save energy.
  2. And  we’re keeping bottles and other plastics out of the landfills.

Let’s look at these arguments.

1) The energy needed to make the rPET is less than what is needed to make the virgin polyester, so we save energy:


It is true that recycling polyester uses less energy that what’s needed to produce virgin polyester.  Various studies all agree that it takes  from 33%  to 53% less energy[3].  If we use the higher estimate, 53%,  and take 53% of the total amount of energy needed to make virgin polyester (125 MJ per KG of ton fiber)[4], the amount of energy needed to produce recycled polyester in relation to other fibers is:

Embodied Energy used in production of various fibers:

energy use in MJ per KG of fiber:

hemp, organic




hemp, conventional


cotton, organic, India


cotton, organic, USA


















rPET is also cited as producing far fewer emissions to the air than does the production of  virgin polyester: again estimates vary, but Libolon’s website introducing its new RePET yarn put the estimate at 54.6% fewer CO2 emissions.  Apply that percentage to the data from the Stockholm Environment Institute[5], cited above:

KG of CO2 emissions per ton of spun fiber:

crop cultivation

fiber production


polyester USA




cotton, conventional, USA






hemp, conventional




cotton, organic, India




cotton, organic, USA




Despite the savings of both energy and emissions from the recycling of PET, the fact is that it is still more energy intensive to recycle PET into a  fiber than to use organically produced natural fibers – sometimes quite a bit more energy.

2) We’re diverting bottles and other plastics from the landfills.


That’s undeniably true,  because if you use bottles then they are diverted!

But the game gets a bit more complicated here because rPET is divided into “post consumer” PET and “post industrial” rPET:  post consumer means it comes from bottles; post industrial might be the unused packaging in a manufacturing plant, or other byproducts of manufacturing.  The “greenest” option has been touted to be the post consumer PET, and that has driven up demand for used bottles. Indeed, the demand for used bottles, from which recycled polyester fibre is made, is now outstripping supply in some areas and certain cynical suppliers are now buying NEW, unused bottles directly from bottle producing companies to make polyester textile fiber that can be called recycled.[6]

Using true post consumer waste means the bottles have to be cleaned (labels must be removed because labels often contain PVC) and sorted.  That’s almost always done in a low labor rate country since only human labor can be used.   Add to that the fact that the rate of bottle recycling is rather low – in the United States less than 6% of all waste plastic gets recycled [7].  The low recycling rate doesn’t mean we shouldn’t continue to try, but in the United States where it’s relatively easy to recycle a bottle and the population is relatively well educated in the intricacies of the various resin codes, doesn’t it make you wonder how successful we might be with recycling efforts in other parts of the world?

pet-recycling-graph-2 SOURCE: Container Recycling Institute

There are two types of recycling:  mechanical and chemical:

    • Mechanical recycling is accomplished by melting the plastic and re-extruding it to make yarns.  However, this can only be done  few times before the molecular structure breaks down and makes the yarn suitable only for the landfill[8] where it may never biodegrade, may biodegrade very slowly, or may add harmful materials to the environment as it breaks down (such as antimony).  William McDonough calls this  “downcycling”.
    • Chemical recycling means breaking the polymer into its molecular parts and reforming the molecule into a yarn of equal strength and beauty as the original.  The technology to separate out the different chemical building blocks (called depolymerization) so they can be reassembled (repolymerization) is very costly and almost nonexistent.

Most recycling is done mechanically (or as noted above, by actual people). Chemical recycling does create a new plastic which is of the same quality as the original,  but the process is very expensive and is almost never done, although Teijin has a new program which recycles PET fibers into new PET fibers.

The real problem with making recycled PET a staple of the fiber industry is this:  recycling, as most people think of it, is a myth.  Most people believe that plastics can be infinitely recycled  – creating new products of a value to equal the old bottles or other plastics which they dutifully put into recycling containers to be collected. The cold hard fact is that there is no such thing as recycling plastic, because it is not a closed loop.  None of the soda and milk bottles which are collected from your curbside are used to make new soda or milk bottles, because each time the plastic is heated it degenerates, so the subsequent iteration of the polymer is degraded and can’t meet food quality standards for soda and milk bottles.  The plastic must be used to make lower quality products.  The cycle goes something like this:

  • virgin PET can be made into soda or milk bottles,
  • which are collected and recycled into resins
    • which are appropriate to make into toys, carpet, filler for pillows, CD cases, plastic lumber products,  fibers or a million other products. But not new soda or milk bottles.
  • These second generation plastics can then be recycled a second time into park benches, carpet, speed bumps or other products with very low value.
  • The cycle is completed when the plastic is no longer stable enough to be used for any product, so it is sent to the landfill
    • where it is incinerated (sometimes for energy generation, which a good LCA will offset)  –
    • or where it will hold space for many years or maybe become part of the Great Pacific Garbage Patch![9]

And there is another consideration in recycling PET:  antimony, which is present in 80 – 85% of all virgin PET[10], is converted to antimony trioxide at high temperatures – such as are necessary during recycling, releasing this carcinogen from the polymer and making it available for intake into living systems.

Using recycled PET for fibers also creates some problems specific to the textile industry:

  • The base color of the recycled polyester chips vary from white to creamy yellow, making color consistency difficult to achieve, particularly for the pale shades.  Some dyers find it hard to get a white, so they’re using chlorine-based bleaches to whiten the base.
  • Inconsistency of dye uptake makes it difficult to get good batch-to-batch color consistency and this can lead to high levels of re-dyeing, another very high energy process.  Re-dyeing contributes to high levels of water, energy and chemical use.
  • Unsubstantiated reports claim that some recycled yarns take almost 30% more dye to achieve the same depth of shade as equivalent virgin polyesters.[11]
  • Another consideration is the introduction of PVC into the polymer from bottle labels and wrappers.
  • Many rPET fibers are used in forgiving constructions such as polar fleece, where the construction of the fabric hides slight yarn variations.  For fabrics such as satins, there are concerns over streaks and stripes.

Once the fibers are woven into fabrics, most fabrics are rendered non-recyclable  because:

  • the fabrics almost always have a chemical backing, lamination or other finish,
  • or they are blends of different synthetics (polyester and nylon, for example).

Either of these renders the fabric unsuitable for the mechanical method of recycling, which cannot separate out the various chemicals in order to produce the recycled yarn; the chemical method could  –   if we had the money and factories to do it.

One of the biggest obstacles to achieving McDonough’s Cradle-to-Cradle vision lies outside the designers’ ordinary scope of interest – in the recycling system itself. Although bottles, tins and newspapers are now routinely recycled, furniture and carpets still usually end up in landfill or incinerators, even if they have been designed to be  recycled [12] because project managers don’t take the time to separate out the various components of a demolition job, nor is collection of these components an easy thing to access.

Currently, the vision that most marketers has led us to believe, that of a closed loop, or cycle, in which the yarns never lose their value and recycle indefinitely is simply that – just a vision.  Few manufacturers, such as Designtex (with their line of EL fabrics designed to be used without backings) and Victor Innovatex (who has pioneered EcoIntelligent™ polyester made without antimony),  have taken the time, effort and money needed to accelerate the adoption of sustainable practices in the industry so we can one day have synthetic fabrics that are not only recycled, but recyclable.

[1]“New Approach of Synthetic Fibers Industry”, Textile Exchange,  http://www.teonline.com/articles/2009/01/new-approach-of-synthetic-fibe.html

[2] Polyester, Absolute Astronomy.com: http://www.absoluteastronomy.com/topics/Polyester and Pacific Institute, Energy Implications of Bottled Water, Gleick and Cooley, Feb 2009, http://www.pacinst.org/reports/bottled_water/index.htm)

[3] Website for Libolon’s RePET yarns:  http://www.libolon.com/eco.php

[4] Data compiled from:  “LCA: New Zealand Merino Wool Total Energy Use”, Barber and Pellow,                                                                       http://www.tech.plym.ac.uk/sme/mats324/mats324A9%20NFETE.htm and  “Ecological Footprint and Water

Analysis of Cotton, Hemp and Polyester”, by Cherrett et al, Stockholm Environment Institute

[5] “Ecological Footprint and Water Analysis of Cotton, Hemp and Polyester”, by Cherrett et al, Stockholm Environment Institute

[6] The Textile Dyer, “Concern over Recycled Polyester”,May 13, 2008,

[7] Watson, Tom, “Where can we put all those plastics?”, The Seattle Times, June 2, 2007

[8] William McDonough and Michael Braungart, “Transforming the Textile Industry”, green@work, May/June 2002.

[9] See http://www.greatgarbagepatch.org/

[10] Chemical Engineering Progress, May 2003

[11] “Reduce, re-use,re-dye?”,  Phil Patterson, Ecotextile News, August/September 2008

[12] “Taking Landfill out of the Loop”, Sarah Scott, Azure, 2006

Why should I choose an organic fabric when I have to put an FR treatment on it anyway?

9 05 2009

The questions is whether it’s a better choice to use inherently flame retardant fabrics such as AvoraFR rather than a natural fiber (like cotton) which has been doused with toxic FR chemicals.  The answer is complicated and like most in this emerging green area, there may be no “best” answer.  We think the answers may lie in the tradeoffs we have to make.  But we’ve got an opinion, and it’s based on the following reasoning:

Fabrics which are inherently flame retardant are synthetics which have been changed at the molecular level to make the fabrics thermally stable and able to pass commercial flame tests.   Some petroleum-based synthetic fibers, such as Avora FR, Trevira CS and Lenzing FR viscose – add a flame retardant to the chemical treatment before polymer extrusion rather than change the molecular structure of the polymer.  This process builds the chemical treatment into the backbone of the polyester rather than adding it later to the finished product.  It is presumed to be less likely to expose the occupants to chemicals.

So how do you compare the two?

When comparing the synthetic with a natural fiber, we think it’s important to look at the carbon footprint of the fibers.  A synthetic like polyester requires much more energy to produce a ton of fiber than does conventional cotton – in megajoules (MJ) of energy the difference is about four times: 126,000 MJ polyester vs. 33,000 MJ for conventional cotton.  Organic cotton is even less:  only 16,000MJ.

It’s important to look at how these fibers are woven into fabric.  (And that’s a different set of carbon calculations).  If the polyester or the cotton is produced conventionally, the finished fabric has residuals of many chemicals which have been proven to harm human health.  The majority of Americans mistakenly believes that the government tests chemicals used in consumer products to ensure safety, accoring to an opinion poll released by the Washington Toxics Coalition.  However, under the Toxic Substances Control Act (TSCA), there is no legal requirements to test most chemicals for health effects, including impacts on neurological development, at any stage of production, marketing and use.  An organic fabric is one which has not used any of the many chemicals used in textile production which are known to be toxic.

So looking at two fabrics (even if one polyester fabric is produced using optimized production methods – i.e., avoiding the toxic chemicals) the organic cotton (or better yet, hemp or linen) fabric is one I’d rather live with.  But fire kills many people every year and we have reason to keep fire codes in place in public spaces.  So the issue focuses on the chemistry used to fire retard the fabrics.

Natural fibers must have a topical FR treatment applied after manufacture.  In the past, these treatments were based on halogenated chemistry, like PBDEs.  The industry is moving away from these chemicals and most have been banned, but decaBDE is still allowed in the US.  With careful attention and questioning of your supplier, you can have a natural fiber fabric that has an FR treatment which meets all codes – and which is not persisten, bioaccumulative and compromises your health.

So now the question becomes how dothe two fibers react in actual fires?

An important thing to remember about synthetics is that they do not burn, they melt.  That’s why protective clothing (firemen, police, rescue) is not made of synthetics – even inherently fire retardant synthetics – because the melting fabric would cause severe burns.

Another issue (and one we think is most important) is that the smoke created by burning or melting fabrics.   Conventionally produced fabrics (natural fiber or synthetic) release chemicals which add an extra dimension to the already toxic smoke.


So where do we stand?

  • With a carbon footprint of 16,000 MJ vs 126,000 MJ (organic cotton vs. polyester) to make the fiber and
  • with organic fabrics having little or none of the chemicals which have been proven to harm human health and
  • because of the ability to use a nonhalogenated FR treatment on an organic fabric and
  • in the case of a fire, not having to breathe toxic fumes from melting synthetics or conventionally produced fabrics

is there really a choice?

What’s the greenest product?

26 01 2009

Did anybody see the Goyard canvas shopping tote for sale over the holidays?  It cost $1065, plus $310 if you wanted a triangular “recycle” symbol painted in gold.  The canvas was advertised as being “100% recyclable”.


Let’s not go into all the ramifications of that one product, but I want to use this example to make one point:  the perfect green product probably doesn’t exist – and maybe never will.  We’ve all heard that the greenest clothing is what you already own, the greenest mode of transport is probably walking  – you get my drift.  Our product choices are all about compromises, and as Leslie Hoffman of Earth Pledge says, “making them with your eyes open instead of arbitrarily is the best piece of advice I could give.”


That’s why we at O Ecotextiles are so committed to spreading the word about what we’ve discovered about textiles and what each choice involves – in terms of our own and our family’s long-term health, in terms of the pollution burden imposed on our planet by the production of our choice, in terms of contribution to greenhouse gases which are contributing to global warming at a frightening pace, and in terms of the workers who made our chosen product (whether they’re children or laborers working under bonded conditions, working in unhealthful working environments).  Your choices do impact you – maybe you won’t see an impact next week, but your choice does make a difference. 


And lest you think that you – one small person – can’t possibly make a difference, remember what Margaret Mead said: 

 “Never doubt that a small group of thoughtful, committed individuals can change the world.


Indeed, it’s the only thing that ever has.”

New research into the effects of environmental chemicals on children’s health

21 01 2009

The new Children’s Environmental Health Center of the Mt. Sinai Department of Community Health and Preventitive Medicine (www.childenvironment.org)  is looking into, as they say, a “whole host of diseases that come from toxic environments”,  including: asthma, autism, allergies, ADD and ADHD, leukemias, brain cancer and birth defects.

The chemicals they focus on in the YouTube videos on their web site include those used routinely in textile manufacturing, and which remain in residual amounts in the fabrics:  lead, mercury, phthalates, other synthetic chemicals; pesticides from the growing of the fibers.  Check it out!

Latest places to read about O Ecotextiles

30 11 2008

In case you’ve missed it, we’ve had some nice writeups about us lately, and thought we’d share them with you, also because these blogs or sites are great resources for your inquiring minds:





Radio Interview with Harry O (he asked great questions!):   http://thegreenhour.com






Happy reading!