Great tip Carol! I had trouble using fray check on a baby diaper set, and was beside myself trying
to get those brown stains out. I've never had that problem before, and of course it would happen
when I was making something special....isn't that they way it always goes?
I've since ditched my Fray-check brand seam sealant, and hesitate to use any kind now....at least
on light color fabrics. I came to the conclusion the stains were due to a combination of products
used on those buttonholes, but I'll never know which combination caused it. If memory serves,
I marked the holes with blue wash-out marking pen, used a sticky back stabilizer, probably some
spray starch along the way....and who knows if I got all the soap out when I prewashed my fabric.
My Fray Check was pretty old too. That might have been a factor.
Since then I've heard from others who had this staining problems. They didn't know
why it happened one time, but not another.