I thought I had a container of Furnace Cement until I opened it and it was rock hard. The reason why I ordered this product. Did a good job of filling the draft in the door, the slider broke off so was filling the air intake as the other door has an air intake and it really isn't needed so it worked fine. The product is easy to apply. with a piece of treated cardboard which I like more than a spatula as the treated cardboard is flexible to glue cement to the vent hole.