My Mom machine embroidered/appliqued a t-shirt for me with mylar in the design. (The design is from Purely Gates.) I have washed it many times and it is holding up fine. The designs stitch loosely over the mylar so that it is tacked down but still shows. I usually put my t-shirts in the dryer for just a few minutes then hang them to finish drying, but I think her shirts are left in until they are fully dry and, last I heard, hers were holding up as well.