Name: Byron
Message: hey, I am an art teacher in Casablanca Morocco and I have to buy my dyes in an open air market.  How can I tell the difference between the dyes if none of the dyes have any labels?  THanks for whatever help you can give

This is a very interesting question.

Often people assume that dyes available in non-industrialized countries are natural dyes, but in fact they are usually synthetic dyes. I would like to urge you to maintain the utmost caution in avoiding direct exposure to these dyes, since some dyes which are considered too dangerous for individuals to use in the US or Europe are completely unregulated in other countries. Always wear plastic or rubber gloves when placing your hands in or near the dye. Never reuse a dye pot for cooking or serving food. Do not breathe dye powder. We are quite certain that some dye workers around the world who use the more toxic dyes, and often scoff at reasonable precautions as though they were unmanly, meet early and painful deaths due to diseases such as bladder cancer.

To find out what kind of dyes you have, you will need to familiarize yourself with the different general classes of dye, and do some test dyeing. See the overview about dyes at my web site, and on all the pages linked to from that page. The process of testing would be considerably shortened if you were able to obtain a multi-fiber test fabric ribbon from TestFabrics, Inc. of West Pittiston, Pennsylvania, but that is probably not practical given your location. Their nearest agent to you appears to be in Egypt.

Here is an overview of tests that you could use for your dyes....

Fiber reactive dye: If a dye works well on prewashed untreated cotton when applied overnight at room temperature with soda ash, it is a cool water fiber reactive dye. (There are also hot water fiber reactive dyes.)

Direct dye: If a dye does not stay in cotton when applied at room temperature, but does if boiled with the cotton for an hour, it is probably a direct dye, which is an inexpensive class of dyes with poor washfastness. 

All-purpose dye: If it does this and also works on wool when used with a bit of vinegar, it is more likely the mixture of direct and acid dyes which is commonly sold as all-purpose dye; note that neither all-purpose nor direct dye will work on polyester or acetate.

Acid dye: If you heat the dye with white wool yarn and a tablespoon of vinegar, an acid dye will tend to leave the water and adhere to the wool, and will tend to stay permanently when washed in cool water. Acid dyes can be used on wool, silk, and nylon, but not on cellulosic fibers such as cotton, linen or rayon, and not on other 100% synthetic fibers such as polyester.

Vat dye: Vat dyes are commonly available throughout Africa. These dyes must be applied in a low-oxygen dyebath, since they are soluble when reduced but insoluble when oxidized. It's not the best dye for a novice to use; improperly applied, the dye will rub off on the wearer during use, showing that the dyer did not use the correct methods. Dyes which wash out after being set with the methods normally used for acid dyes on wool or direct or reactive dyes on cotton are likely to be vat dyes. You can learn how to use vat dyes by following the instructions provided for PRO Chemical & Dye's vat dyes. Also do web searches for more information on indigo and other vat dyes. It may be easier to find the chemicals used in "natural" indigo dyeing recipes; indigo may be natural or synthetic, and all other available vat dyes are synthetic, but the natural methods should work the same for the synthetic vat dyes.

Vat dyes can be used on both cellulose fibers such as cotton, and protein fibers such as wool. They cannot be used on synthetics other than viscose rayon (which is very much like cotton).

Disperse Dye: If you paint your unknown dye onto paper, having first mixed it with water to make a paint, and then iron it onto polyester fabric with a very hot, dry iron, if it works well, then what you have is disperse dye. This seems less likely than the other possibilities, since disperse dye is useless on natural fibers.

Basic Dye: The earliest synthetic dyes were all Basic dyes. They are not at all lightfast, and some are quite toxic. They are the best dyes for use on synthetic acrylic fiber, though they must be simmered with it (never reuse the dyepot for food!); they can also be used on cotton, silk, and wool if they are pre-mordanted as for dyeing with natural dyes, or by pre-dyeing with direct type dye.

Naphthol Dye: Finally, the other major class of dye is naphthol dye, in which the different components combine chemically in the fiber to create different colors. These are commonly used in Indonesia and some Asian countries. Many of the components of naphthol dyes are quite carcinogenic; I urge you to be particularly cautious in their use. However, some direct dyes and some acid dyes are also quite dangerous.


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