My husband has old lumber stored in the garage. Our house is very old and the garage often get cold and damp. He went to use a piece lumber out of the garage to build a shelf. it had tiny black pin dots on it. I wiped it down with water and a little bleach and the dots are still there.I think this this either a form of mold or mildew.. Am I correct and if so can we use the lumber inside for the shelf?