There are different types if mylar so it is best to make a sample and wash, dry, and iron test. Noticed some are thin and others thick.
it can be washed if you use the clear Mylar, not the coloured ones. hugs Gerry
I stitched out three poodles with Mylar backing on some cotton fabric. I put the stitch-out test on a pile of other stitch-outs. A mouse got into the house and ran over my fabric (Gasp!@!!)....
I tossed the lot into the washing machine, normal wash with 40F water, as it was a matter of survive or be tossed out and burnt.
To my surprise all the stitch-outs survived perfectly. I ironed all the fabric on the back, including the Mylar designs, and, again, to my surprise the Mylar survived good as new.
I bought my Mylar from ... www.heirloomsbysharon.com
Well, I could have just said Yes, couldn't I.
AlmaG.
Beware, if you use the colored wrapping type "mylar", the color will run. I learned the hard way. But it holds up fine in the wash and dryer.
I wash it normally and iron on the back and have had no problems
I believe there can be some colour run from the stronger colours. Irridescent seems to be ok.