Seller’s Website

From their website:
“This yarn is…dyed with all natural dyes using alum/cream of tartar mordants to preserve the organic qualities of the wool. The tradition of natural dyeing with plants from the wild, and exotic natural dyestuffs traded across continents, has been practiced for 400 years by our ancestors and many years before that in the Hopi, Navajo and Pueblo tribes.

Our indigo shades are vat dyed by slower traditional bacterial methods to avoid the harsh chemicals introduced in the last century. Brightening, greening & dulling are achieved by dyeing with pure tin, copper & iron rather then using metal salt after baths. No chrome is used.“