My friend Tracy came over yesterday bearing indigo stock solution and we proceeded to dye all day. It's hard to believe that I have been using natural dyes off and on for years because it involves things like math and chemistry. To give you an example, I know there is a process called oxidation that happens after you pull the fiber/fabric out of the indigo vat. The fabric is initially this chartreuse green and right before your eyes it turns blue. This is caused by oxidation, but I call it magic.
We used a chemical indigo vat where we substitute things like lye and thiourea dioxide for the oatmeal, rice, rhubarb leaves, and other natural plant fibers used to create a natural dye bath. The dye bath has to be ph'd properly and chemicals measured and checked often so here's math and chemistry. I think my chemist friend, Janet, would be both proud of me and also laugh at me .
In this picture you see some of the dyed pieces hanging to dry. The darker shade of color you want the more dips in the dye pot. The piece must stay in the pot for at least 30 seconds and up to a minute. Then you wait 20 minutes before you dip it again.
I shibori dyed some dupioni silk but I don't think I dipped enough times in the dye pot and I'm afraid most of the color is going to wash out. With indigo you always have to dip more times so the fabric looks darker than you want it because it is the nature of the dye to wash out a lot. It helps to "cure" it longer by letting it set. You should let all indigo dyed pieces air dry for at least 24 hours. I'm going to let this piece set longer and see if I can retain some color.
Here are some more pieces of lace and crochet I dyed along with some shibori dyed silk ribbons. I'll post pictures of these again after I wash and iron them.