community of dyers

Interesting. I'm glad you'll be doing testing on it.

The idea does not appeal to me very much. Since it's not a process like mercerization, it's likely to be a cationic pre-treatment, which causes just about anything with a negative charge to stick to it. It's described at Cotton Clouds like this:

EZ Dye Cotton Sliver is created by adding a molecule to the cellulose that attracts and permanently bonds to a dye molecule, causing the fiber to take dye without the use of auxiliaries such as salt or washing soda.

Sounds like it must be similar or identical to a cationic dye fixative like Retayne. The Weaver's Loft says "it has little to no effect on lightfastness." That to me looks like the claim you're likely to see on something that does affect lightfastness; cationic dye fixatives commonly reduce lightfastness.

I'd like to see washing instructions, for a clue as to how washfast material dyed with this treatment may be. For example, the instructions on Rit Dye Fixative say to wash clothing treated with it only in cold water. While the EZ Dye treated fiber can be used with fiber reactive dyes, they're not likely to form the permanent chemical bond that fiber reactive dyes do when used correctly with soda ash or another high-pH fixative. Washfastness is probably better than for direct dyes used on untreated cotton, though.

Of course, as always, we are given no clue as to how toxic the fabric treatment may be if absorbed from the fabric through the skin. We have no idea, as always with anything used on textiles in the US, whether it contains a significant amount of formaldehyde or other unpleasant chemical. Ordinary commercial clothing certainly does. Only our hand-dyed PFD materials do not.

-Paula