My daughter will be 16 tomorrow and I taught her to sew about 5 or so years ago. She's really into cosplay and goes to several conventions a year. She's made a LOT of costumes. Luckily she has a part time job to support her "habit". Frankly, her costumes are far better than any I could make.
Anyway, she started making a new cosplay... Connor from Assassin's Creed. I had just learned about the crayola washable markers for quilting and my daughter started using those to mark her fabric. I didn't think anything of it until I saw she had ironed the hood piece and I saw it still had marker on the fabric. (!!!) A good soaking, Shout, and wash later, the marker came out thank goodness! It didn't occur to me that she would start using what I had been. Of course she didn't know to test the fabric first to make sure the marker would come out and to NOT apply heat because it could set the ink. Luckily no harm was done. It's a good thing because the outfit is made of heavy linen and it's uber expensive!