Welcome to Studio 39 Fabrics!
Overdyed, 100% cotton floss.
The following information is provided by The Gentle Art:
Sampler Threads™, Simply Shaker Threads™ and Simply Wool ™ are colorfast, meaning that they will not change color when washed, will not fade if kept out of direct sunlight, etc.
Although great care and detail is taken during the rinsing process, there is a slight chance that some surface dye may remain on individual threads. It may sometimes be difficult to rinse off all the dye that is on the surface of the thread when dyeing in large quantities as The Gentle Art does.
If you would like to wash your piece AFTER stitching, The Gentle Art recommends that you could do the following only as a precaution:
It is safe to rinse Sampler Threads™ and Simply Shaker Threads™ in hot water BEFORE stitching. Blot them on a white paper or terrycloth towel to see if there is any residual surface dye remaining. You may repeat this process several times until they rinse clean. Again, the color will not fade. Let the threads dry (it won’t take long) and then stitch. Piece may be gently washed after stitching.