What are the stains on my basement wall?
Most stains are caused by moisture. The white chalky stains are efflorescence, which is a deterioration of the cement as the water passes through the block. The brown stains could be mold or they could be acid stains from water passing thru a highly acid soil. The black stains could be mold and mildew. Mold will grow on painted surfaces more so than it will on a bare block because most paints have organic properties which gives the mold something to feed on. Any of the stains indicate the presents of water.
