Try cutting off a piece of the floss and dipping it in hot water in a white bowl or cup. That is a good test.

Some are, some are not. I prefer Weeks Dye Works overdyed floss,.they are colorfast. The 1% of WDW that is not colorfast is so labelled. I cannot trust other brands and have had bad luck because on the one side of the label it says COLORFAST by industry standards, yet the other side of the label says to rinse in hot water and blot with a white towel (I use paper towels without prints on them).

Colorfast? Look in any dictionary. The description is very good. Unsure? Rinse or even wash and rinse

Hello,

Per the Gentle Art website, the Sampler Threads, Simply Shaker Threads and Simply Wool threads are colorfast. They also go on to state that:

"although great care and detail taken during the rinsing process, there is a slight chance that some surface dye may remain on your individual threads. It may sometimes be difficult to rinse off all the dye that is on the surface of the thread when you dye in large quantities as we do.

If you would like to wash your piece AFTER stitching, we recommend that you could do following only as a precaution"

Here is the link the Care Section on their website if you would like to read a bit more about it:
http://thegentleart.com/ga/care.htm

Hope this helps :)

~Kristi @ ECS