Name: Donna
Message: Hi- I am collecting walnuts, goldenrod, sassafras and poke weed to use on 100% cotton (white and natural) petite canvas bags.  The handles are polyester so they will probably not take the dye. We are going to sell these to raise funds for our local animal protection agency. What is the best way to obtain the colors from these natural materials and what is the best way to fix the color into the material.  I was told 2 different things- use urea or use soda ash.  What do you recommend? Thank you for you help !!! 

Please don't sell anything you make until after you have tested it for washfastness! Make absolutely certain sure that dye does not rub off when dry, nor bleed when wet, before selling anything. As a general rule, natural dyeing requires a lot of experience; the application of natural dyes is much more demanding and labor-intensive than that of synthetic dyes. A beginner's first experiments with natural dyeing do not usually result in professional-quality goods that are suitable for sale. 

Neither urea nor soda ash will fix your natural dye! Urea is a humectant used to retain moisture during reactions of synthetic dyes. Soda ash, which is the main ingredient in washing soda, merely increases the pH, which is essential for using synthetic fiber reactive dyes on cotton, but will not assist in setting natural dyes. Whoever told you to use urea or soda ash to fix natural dyes is not an expert in the dyeing process.

In order to set natural dyes in your cotton, you must pre-mordant it. I recommend that you acquire a copy of Dagmar Klos's book, The Dyer's Companion, which contains detailed recipes for mordanting cotton and other fibers. The  Art and Craft of Natural Dyeing, by J.N. Liles, contains recipes for mordanting cotton, as well, but it is not as easy for a beginning dyer to understand. Use the alum-tannin-alum method of mordanting for best results. Boil your (prewashed) cotton bags for the indicated time in the indicated strength of alum. Next, repeat the process with tannin. For your third step, repeat the alum treatment again. Only after this three-step premordanting process has been completed can you apply the dyestuffs. You will need to find a good recipe for dyeing cotton with each of your natural dyes, as well. Most natural dyeing books contain recipes only for wool, which is vastly easier to dye than cotton; wool recipes cannot be used for cotton. As a general rule, you will need one to two pounds of natural dyestuff for every pound of fabric, and, in most cases, you will need to boil or simmer the dyestuff for some time. Weigh your canvas bags so that you have an idea of how much you will need. If your stack of bags weighs five pounds, in general you should collect ten to fifteen pounds of dyestuff to use on them. It is only dye extracts and synthetic dyes that can be used in smaller quantities than the weight of whatever fabric you are planning to dye.

Walnuts are probably the best and strongest of the dyes that you propose to use. Because of the tannins in the walnuts, you can omit the tannin step in mordanting cotton to be dyed with walnuts, though the alum is still important. I have seen recipes that call for grinding the hulls of green walnuts and letting them rot for a week before using them in dyeing. Lile's book The Art and Craft of Natural Dyeing contains recipes for dyeing cotton and linen with walnuts, but warns that pokeberry gives only non-lightfast results, and that only on wool, not cotton. This book includes a recipe that says that a half-pound of goldenrod flowers is sufficient for one pound of cotton, mordanted with alum/tannin/alum.

Interestingly, when my son used turmeric to dye various fibers for a science fair project, the polyester which had been mordanted with alum did take the dye, a nice yellow. (He boiled the fiber in the alum and then in the turmeric, I think for half an hour each.) If you try turmeric, which is a rather easy-to-use natural dye—only a few spoonfuls are needed—be sure to label your goods with a warning that the dye is not lightfast and will fade with time. Unlike most other natural dyes, turmeric can dye unmordanted cotton, which makes for a much simpler procedure.
 
The idea of natural dyes is very appealing, but, as you can see, this is no beginner's project that you have undertaken. You should obtain recipes in a trusted dyeing book in order to have any hope of success, and you will need to allow plenty of time for trial and error as you learn to correctly use mordants and natural dyes. 

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