Wednesday, April 06, 2011

About vat dyeing

A couple questions came through regarding 'what is vat dyeing - the process, the effects to achieve? Vat dyes are a distinct class of dyes that are applied at fairly high heat, compared to MX, at least. Temperatures between 120 - 150 degrees F at any rate, with Thiox as a reducing agent (no oxygen in the bath) and lye to raise the pH very high. Because of the Thiox, color is removed at the same time that the vat dyes are applied. Because the thiox creeps farther than the dye does, you can get halos around the new color. And you can over dye a dark color with a lighter color, because the original MX (in my case) color is removed. Vat dyes also work on other types of dye than MX, but I'll have to check my notes to be sure. I do know other fiber-reactive dyes will discharge. But because of the extreme pH, you can't use vat dyes on wool. With TLC, you can use it on silk. Here's a close-up of a section of the gold and purple fabric showing some haloing where the darkest color creeps across the slightly lighter violet diamond:

The process is a little more hazardous than working with MX - more safety gear is required because of the lye. But the results are worth it, and once I practice, practice, practice, I hope I'll be able to get results like the photos in my March 26 post. Nothing like wanting to achieve the work of the master on day 3 of class! Elin has another class this summer at Whidby Island - go there if you can!!
I hope to continue with vat dyes, as well as MX and disperse and to keep adding pictures here and at, where I sell my fabric. Thanks for looking, and for the encouragement!


Debbie said...

Really interesting post. I wonder if it would work with cotton yarn? Only one way to find out I guess....