There is a lot to fabric then just what it’s made out of. What is the weight of the material? Are you using interfacing? Cotton in general washes out because it makes ash. There is a post I did with option on waterproofing it to help prevent it some. But polyester is what I mainly use for fabric engraving. These items were engraved with the glowforge and the photo was taken after it came out of the wash:
