OK, I just washed it with Dawn, rinsed and ironed it dry. The white number is still there! This is on a kind of maroon colored cloth. I'm sure the mark is on the light fabrics too, just not as obvious.
I don't think I'll use it anymore.
Originally Posted by QuiltnNan
wow, that's a bit scary... could you do a test piece and wash it to see if it comes out then?