No it does not wash out. I have only done it once but it still is holding after washing. I do like you, sew the front etc... I do the back differently depending on size and such. I did a little check book cover and used only seam a steam on the inside binding. Looked great. So it depends. But the thread is fusible, lasting fusible. The only thing is there are different brands, so I don't know about all. The project I used the fusible thread on was a table runner for myself (for a change) and believe me it has been washed and still is fused. It was so easy, I put the thread in the bobbin and when I sewed the top binding on the bobbin thread went to the back and then I ironed and yep done. There are spots that could have been done better. Try it on something small like a hot mat or something, then the most that will happen is you will have to sew the binding on if it does not stay. My fusible thread I have now does not have instructions so I am wondering if it is lasting fusible. So I am going to give it a try. Probably the same as yours but not sure. Got a good deal from Sewing with Nancy on line so bought two spools. I'll let you know what happens.