"Dragnet" premiered on TV on this day in 1951. It was raining and we were working the "Masonry Stain" detail. We're on our way to Azusa on a 911 call, possible efflorescence. Not a pretty picture. I'm Detective Joe Friday. Open up, masonry police! Understand you've got chalky white stains on your bricks. Could just be paint oxidizing and washing down off window trim and siding. If so, no cause for alarm -- just unsightly. Or it could be something far more serious, efflorescence -- mineral deposits left when water passes through bricks and evaporates on the surface. To check it, wash the chalky stain off. If it stays away it's OK. If it returns or gets worse, water is moving through the wall and you've got a problem -- efflorescence. If so, call a masonry professional. Those are the facts. And that's the On The House tip for today.