I bought the pens last weekend and was very disappointed in them. They seem to disappear on light fabric OK (it still remains to be seen if they reappear), but on dark fabric it leaves an opaque line. I will NEVER use them on dark fabric and possibly never at all. On the bright side, my daughter had a great time writing a letter to a friend and them ironing it clear! Her friend has to put the letter in the freezer to be able to read!