My grandmother used to do this with me when I was a kid (we won't tell how many decades ago that was). But, we used regular crayons and just covered the fabric with wax paper and ironed them really. The heat melted the crayons into the fabric and it worked great. I'm not sure if we washed them, but if you have crayons and some scrap fabric, it would be worth the time to test it out. I was past my coloring days also, but it was a lot of fun.