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The Myth of the Bad Mordant

by Cheryl Kolander, Master Natural Dyer, Aurora Silk, since 1969

In answer to a question whether natural dyes, especially mordants, weren’t just as polluting / dangerous / bad as synthetic dyes.

My perspective is that all synthetic, chemically produced dyes are terrible poisons.  They are manufactured from coal tar, which is what is left over from a barrel of petroleum after the gasoline and kerosene are boiled off.  All kinds of incredibly dangerous and poisonous chemicals are used to turn the basic hydrocarbons of coal tar into the various benzene rings that vibrate with light and can function as colours and dyes.  These same artificially produced compounds are well known to be some of the most carcinogenic and polluting substances on the planet.  For example, synthetic red dyes are now restricted as food additives, for all are recognized carcinogens, while Cochineal (Natural red dye #4) has become the safety standard. (1) And synthetic yellow exposure has long been implicated in developmental disorders of the nervous system.

By contrast, my investigations over these past 15 years, since I studied at the National College of Naturopathic Medicine, have proved that all natural dyes are natural medicines, and none, even if dumped at full strength, are more polluting than leaf tea. 

As for the dred mordants, I do believe there’s a web-site posting of my paper on Chrome, which was presented at the International Natural Dyers Conference in Ames, Iowa in 2002.  Chrome, that is, potassium or sodium dichromate, is the only mordant that is used in home dyeing that might be questioned.  In addition to the logical and reasonable approach to the safe use of chrome mordant by the home or art dyer, I calculated the actual impact of my own personal chrome mordant use.  I use tiny amounts of chrome mordant for almost a third of my Aurora Silk hand dyed art colours.  Using conservative estimates, I was surprised to discover that the impact of an art dyer much like myself (who always recycles and reuses mordants) is approximately equal to the pee from 1/80th of the population of Portland, since that many people take vitamins and mineral supplements that include chrome as a necessary trace mineral.  In other words, 80 art dyers working daily would barely equal what is now being peed out daily, and no one complains about this.  And shall we mention the tons of chrome that is dumped daily by US industry into our waterways? And shall we note that most synthetic dyes and paints are compounded with chrome?   Yellow, green, brown and black synthetic colours are rarely based on anything other than chrome! 

Alum is sold in grocery stores and for better or worse you eat it every day.  It is ingested by all Americans in commercial baked goods (it’s in the baking powder), pickles, spaghetti sauce, all restaurant meals (which are cooked in aluminum pots) etc, etc.  It is rubbed into the skin of probably more than half the population, as all antiperspirants, including so-called natural ones, are based on alum, because of its astringent qualities.  Personally, I avoid all exposure to aluminum internally.  And when we dye, we always wear protective gloves, so as not to absorb anything through the skin.  Besides my standard dye works practice of re-using mordant baths and never dumping them, I must here point out that most alum used today is used to “purify” water.  It is added to the water systems of many cities, to precipitate out impurities.  Many people, if not most, are ingesting substantial amounts of alum in water, every time they use the tap.

Iron also is incredibly abundant in our lives.  It is the main ingredient in iron supplements and products like Geritol.  Rusty pipes contribute visible iron to the drinking water of many households.  People complain about the colour, but no toxic effects of this rather high exposure have been reported.  In fact, iron ores have long been honored as sacred, for their life giving properties. The so-called “red clay people”, who were an ancient pan-arctic culture, buried their dead smeared with red clay, with caches of red clay, as iron supplement meant life.  This is still true, as any formerly anemic person will affirm.

The whole hype is misinformation, I suppose promulgated by a dirty industry
that doesn’t want any threat, (like the art or home natural dyer!) to cut even
a fraction of a percent into their profits.  That is the standard American
way of doing business: cut your competition no matter what lies you tell nor how small the competition is now.  It is not impossible that people could start one day to question the poisons they put on their bodies, just as 20 years ago they began en masse to question the poisons in the food put into our bodies.  Now there is a huge, growing natural foods industry.  What if people decided the extra cost of natural dyes was worth the benefits: in health for themselves, the planet, the economy (especially of third world countries), and for the BEAUTY.

In times past, cotton dyeing used heavy metal mordants industrially, but
NOBODY uses these mordants now.  We use only Alum, tin, iron and a tiny bit
of copper and some of us use a tiny bit of chrome. (2,3)

In contrast to the standards applicable to the home or art dyer, my industrially dyed silk fabric “by the bolt” colours are all dyed using only alum, tin and iron.  Even dyed by the bolt, the amounts used are minuscule.  However, when the natural dye industry reaches commercial status, it will be a requirement of my (hoped for) dye works to reduce / reuse / recycle / conserve everything, and to have an on-site wastewater precipitation tank and natural treatment wetlands.

I have been a daily natural dyer for 35 years.  My health is very good.
Synthetic, chemical dyes are so poisonous they have destroyed rivers all over Germany where most manufacturers are.  Chemical art dyers of my generation have dyed of cancer, because they did not take the necessary precautions of gas masks, clean work clothes, hood fans, etc that these poisons – freely sold – require.  I wish the true nature of these poisons were better known.  I have devoted my life to the alternative: Beautiful colours, safe dyes.

Many people ask the same questions of me, here is an original email from a concerned consumer

The original inquiry follows:


Thanks for the email.

Today has been really interesting. I have had a day of seminars
regarding sustainability and toxins/poisons created by manufacturing
and from the waste of designed objects. One of the lecturers mentioned
natural dyes and yet somebody questioned that the mordant metals for
fixing dyes are extremely poisonous and polluting. Are they just
polluting if they are let out into the local water systems? Is it ok if
you recycle the water back into the studio system to re-use again? Or
is it that the metals are polluting to the environment but not toxic to
people in their homes?

I have been told that todays dyes are no longer toxic and that just
because they are synthetic does not mean that they are poisonous and
just because they are natural does not mean that they are

-J. W.

My original response to the inquiry.

1 – “Truth in labeling laws do not require cochineal be listed as a colourant. It is often grouped under “natural flavours”.  “Carminic acid” is a synonym.  Only Jones’ Sodas list it, but all cranberry juice contains it.

2- TIN has been ingested from tin-lined cans for about 100 years, with no noted negative effects.  Negative effects were noticed from the lead in the solder used to form the cans.  Thus tin cans have mostly now been replaced by aluminum or enamel lined.  Tin is a mineral the body needs

3 – COPPER has been ingested from copper water pipes in soft water regions for centuries.  No noted negative effects were noted from the copper, but negative effects were noticed from the lead in the joint compounds.  The best water systems are clay or glass.  Now we mostly have PVC that leach carcinogenic poly-vinyl-chlorides into our water.  A deficiency of copper is very common and results in arthritis; thus, the wearing of copper bracelets helps many sufferers by delivering copper, in the form of the green copper oxide that discolours the skin, right into the joint.

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