I found two pre-owned white cashmere sweaters in a vintage clothing store and dyed them with the same blackberry leaf dye bath but achieved very different results. I premordanted one sweater with alum before putting it in the blackberry leaf dye bath, and it became bright yellow. After dyeing the other sweater, I processed it with an iron aftermordant, which turned it teal gray-green.
You can have fun with this kind of experiment. Choose an old white sweater from your drawer or pick up one from the local thrift store. Check the sweater label: any sweater you use for this dye project should be 100 percent wool or another natural fiber to assure even dyeing.
Excerpted from "The Handbook of Natural Plant Dyes: Personalize Your Craft with Organic Colors from Acorsn, Blackberries, Coffee, and Other Everyday Ingredients" by Sasha Duerr, published by Timber Press. Images by Sasha Duerr.
Use the Blackberry Leaf and Stem Dye recipe to make your own sweater.