Thursday, September 17, 2015

Dye Plants--Colors of Red Cabbage Update

I don't see a way to upload a photograph into Comments, so I will respond here to a question on the red cabbage dyed cloth.

The original post: The Colors of Red Cabbage

Saffi commented on 9/11/15 "Lovely post with clear instructions and great pictures. Can I ask how the silk is one year on? Has the colour faded or changed at all? "

I located the silk pieces from that project. Below first, are the pieces photographed dry, from top to bottom they are alkaline, neutral and acid. The rug underneath is beige.
red cabbage-dyed silk rephotographed
red cabbage-dyed silk.
Top to bottom: alkaline, neutral and acid.
photographed dry on 9/17/15

I wet them in my tap water (which is alkaline) and got the colors below: alkaline, neutral and acid from top to bottom. Because they were wet I put a towel underneath. It is white.
red cabbage-dyed silk, rephotographed
red cabbage-dyed silk.
Top to bottom: alkaline; neutral and acid
photographed wet on 9/17/15
Here is the photograph from 2014, the pieces sitting on some kind of white cloth over the beige rug. They were wet, having been rinsed after dyeing.
red cabbage-dyed silk and wool, 2014
red cabbage-dyed silk and wool;
Left to right: alkaline, neutral and acid
photographed wet 4/22/14
I could find only one of the pieces of yarn, and it is colorless, but it is the neutral pH that was essentially colorless in the photo from 2014.

I kept the silks in a plastic bag at room temperature, out of the sun and didn't take them out much, so that's pretty substantial fading in a year. On the other hand, cabbages are cheap: you could redye once in a while when the garment started looking faded. 


In April, 2015 Christi Dea commented:  "found that my alpaca fibers were wash fast and light fast when I premordanted them with myrobalan (which makes a butter yellow). I'm thinking that maybe the alum blocks the absorption of red cabbage dye on wool since the dye is water soluable and the alum salts are coating the fibers. Possibly mordanting AFTER I dye may yield better results?" 

I didn't answer that and still can't. I've never worked with alpaca or premordanted with myrobalan. The mordant I used, alum, is a metal that links the colored molecules of the dye to the fiber. Myrobalan is a tropical tree which dyes things because it is rich in tannins. Tannin dyes don't need mordants, but are not themselves mordants. The chemistry of this suggestion is beyond me to analyse. See discussions of mordants, tannins and myrobalan in D.Cardon, Natural Dyes. Archetype Publications, 2007.

Comments and corrections welcome.
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Kathy Keeler


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