This was my comment from this topic:
http://www.quiltingboard.com/links-resources-f4/heads-up-crayola-washable-markers-t267532.html
"I have used the ones marked 'ultra - clean - fine - tipped - Crayola - markers'. They wash out.
Someone recently said they ironed over them and they still washed out, so I tested ironing them thoroughly and it WASHED OUT. I tend to have to test things for myself so I suggest you experiment on a sample piece of fabric and find out if it washes out."