|Carbon oxide is used as a mordant*. It's also added to various plant-based dye baths to manipulate a range of colors.|
I'm working on a a technique for bleaching + dyeing cotton and I sure would like to get a hold of some natural, non-toxic dyes. In a university fiber arts class we used the most brilliant, yummy dyes for batik and tie-dye projects, but alas, I'm afraid it was rawther wicked stuff. I can still envision the shocking blues and purples I was able to achieve in my pieces.
Ecouterre has a cool article about Awamake, a Peruvian natural dye business and I hope someday soon they have small quantities of product available for the small-timers like us!
* a Mordant is defined as: A substance, typically an inorganic oxide, that combines with a dye or stain and thereby fixes it in a material.
Now... off to find some currently available natural dyes.