Have you ever shot canned foam and when it cures it looks like this? Where it’s shrinking or cracking or just not curing properly? The reason behind that is pretty simple: polyurethane needs moisture to cure properly. The reason behind it is probably a lack of humidity. Our polyurethane foam gets used all around the world all year long. Especially in desert environments or on low humidity days, you should always mist the substrate that you are using the foam on. This really helps activate the curing process. If there’s not enough humidity in the air it’s not going to cure the right way. After you apply the foam if you mist it a second time, that will ensure that it will cure properly. Look at these two differences side by side. The difference is visible. So, a little bit of water goes a long way here. It will help ensure you get the right seal.