I just inherited an old one story log cabin. The exterior chinking appears to be mortar. The interior chinking is a mystery material. It looks like it is loose because it is fuzzy, but it is hard to the touch and dark in color. I can not pull it out. This interior chinking seems to function well but it collects dust and Iseem to be allergic to it. Can you guess what it is? Can I apply a latex chinking over it?