Hi! I have always used 'jelly roll' gel pens for writing on my quilt labels. After writing the label I then heat set the ink with the hottest iron temp which seems to set the ink pretty well. So far I have not had an issue with the ink washing out. With that said, all gel pens are not created equal.....some do wash out even after heat setting. I would suggest you make a test piece of fabric using your various gel pens, heat set them, then toss in the washer and see what it looks like after washing. I hope this helps.