Chalk inks on fabric

[joystamp4]

I read several posts a while ago about how well the petal point inks were for fabric stamping. So, I used them to stamp some shirts for my granddaughter. They were all cotton, washed and dried before stamping. After stamping, I put them in a hot dryer to set. Yesterday she wore the first one and as soon as the drool hit it, the colors ran like crazy. What do you think I did wrong?

Joy

[Edie32]

I've never used these on fabric before - but have always wanted to try.
They say they're permanent when heat set.

I guess I'd try it again on a scrap of fabric and use an iron.