I've been using Crayola washable markers for years and never had a problem. I have left quilts go for month with the marks on them and they came out. I have never washed a quilt in hot water though. I use cold water. I have iron them and they still came out. I was originally told to use them by a quilt shop owner. She has closed her shop and now sells kits on the internet. She attends our quilt guild and last I talked to her she was still using them also. Never a problem here, must be our hard water.lol