Very interesting stuff. It has two layers so when you knead a chunk the inner and outer layers blend and the hardening begins. I used it to repair fiberglass and vinyl body pieces on a motor home and it did not adhere very well. The one drawback is the setting speed. It is very hard to cut it knead it and apply it before it hardens. If you take the time to press it firmly in place and smooth it you may find that it has gone brittle and won't hold up or stick. You need to work fast and if you are doing more than a tiny repair you need to work in smaller sections to avoid having it harden before you can get it in place. A ten or fifteen minute version would be better. Who is in that much of a hurry?