Originally Posted by JJBlaine

The thing to remember about using fusibles like heat and bond, or wonder under, is that they are thin layers of heat activated glue, and that new unwashed fabrics are treated with sizing and other chemicals that can sometimes repel the glue, causing adhesion problems.

If you do not pre-wash your fabrics, or if you put your project in the washer in hot water, or into a hot dryer, the heat is going to re-melt the glue. That is why it comes loose. Cold water and line drying should cause no issues.

I used to use wonder under on fabrics with large Hawaiian style prints, cut out the individual flowers, and adhere them onto clothing. Then I would go around the edges and outlines with puffy paints. The only time I had any issues with adhesion was when I used unwashed clothing and/or fabric, or when I mistakenly tossed the shirts in a dryer. Some of my sweatshirts lasted for years when properly cared for.

Personally, I do not care for fusible when I am quilting. It comes out just too stiff for my liking. I also tend to have issues with it gumming up my needles. Yes, the fusible does keep the fabric edges from fraying, but I prefer to use some fray check for that if I need it. If I'm doing turned edge applique, I use Elmer's glue sticks.