Mordanting? Do I Need To?

Over a month ago was when I got my first batch of onion skins from Danny, our Chef and I said maybe I’d start “next week”. Now I’ve been at it for 2 ½ weeks. The apartment is more of a mess than ever with fabrics everywhere, dye samples, and bundles of dyes. I was excited with my results until one day when Yoshiko Wada called and said I must use a mordant with onion skins as a dye. We mordanted in dye classes I took, but I’d never done it at home, only choosing dyes that don’t need mordants (which I thought was the case with onion skins). I did have alum but never used it, so I guessed I’d better try it.  A mordant is a metal salt that is used to fix a dye in a fiber. The word comes from the French word mordre, which means “to bite”. Usually it is done before the fiber is dyed, but not always.

Here are two bundles of silks; the stiff ones (undegummed) are on the left and the silky silks on the right. Boy, does silk dye deeply and easily. There were all mordanted in alum. It wasn’t such a bother as I thought.

I put a small batch of unmordanted silk in with the mordanted into my pot of onion skin dye.

This book became my bible. It is so user friendly. It does refer you to another page often, but the organization makes it easy to use. And I took notes for what I needed. I took a class with the author; Catharine Ellis last fall and it was wonderful. I just hadn’t looked into the book until now. I knew that my linens would be the next challenge and really appreciated everything she wrote about dyeing (and mordanting) cellulose fibers as well as silks.

Because I’ve promised myself that I am going to dye the fabrics I brought back from India, I knew I needed samples first to determine which fabrics would do what. It was fun organizing this swatch chart and it took a good bit of time. The 11 degummed silks are in the left 2 columns and the 10 stiff silks (undegummed) in the right two, for a total of 21 different silk fabrics. The unmordanted ones are the left ones in the pairs. Looks like there is very little difference in the colors with the mordanted ones. However, Yoshiko said mordanting made them more color fast. Since mordanting wasn’t so onerous, I guess I can entertain the idea of mordanting a lot more (or not??)

6 thoughts on “Mordanting? Do I Need To?”

  1. Peggy,

    I use different pans to act as the mordant for some of some of my dyeing. IE. a copper pan, enamel with alum. etc.


  2. Rats! I was looking for the next several paragraphs about your dying adventure. Guess I’ll have to wait for the next chapter. BTW, these samples are gorgeous and so fascinating.

  3. I also thought it was not necessary to mordant ahead of dyeing with onion skins, until I did it. I made a shirt from Kona cotton that was “prepared for dyeing”, meaning that it didn’t have brighteners and things. When I dyed it with onion skins it was a bright beautiful color. I wore it regularly and the color eventually washed out, much to my dismay. After a year I dyed it again, but I believe I mordanted it first. The color faded again. I met Catharine Ellis in March and was very impressed with her work with cellulose fabrics and bought her book. Before I get around to dyeing again, I’m going to study it.

    • Thanks for that. I’m really glad to hear from experience. Boy, did you gave your shirt lots of washingbefore it faded.

  4. These are beautiful colors. Do you need a pound of onion skins per pound of fabric/fiber? And are these yellow onion skins?


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