Q: I have a wood deck that I have stained twice in six years with semi-transparent stain. The second time was a disaster, and the stain is peeling and chipping. Both times I cleaned and power washed the deck before staining. I can't remember the brand of stain I used. What could cause this, and do I need to strip the deck before staining again?

A: You probably mixed two types of stain, one latex or water-based and the other alkyd or oil-based, and the stains are not compatible. The best bet when finishing a deck for the first time is to pick a high quality product of a given type, then stick with it for future applications. Cut the label from an empty can of finish and file it for future reference, so there will be no question about what was used.

You will need to strip the deck now and start over. A number of products are available at home centers to remove deck stains. You should pick one, such as Flood Wood Stripper Premium, that will remove both oil-based and water-based stains. Be sure and read all the directions before starting, and follow them carefully.

Some top brands among deck stains are Flood, Olympic, Cabot, Sikkens, Thompson's and Wolman. Latex stains have less odor and clean up with water, but oil-based stains often are considered more durable. Read labels and ask questions of the dealer before you pick the stain you want to live with.

Q: My fiberglass shower has a chip and some scratches on the floor. How can I repair them?

A: Fiberglass repair kits are available online and at some home centers and marine-supply stores. One online source is www.bathwizard.com. Repair kits cost $29 each and are available in three colors.

Q: Water seeps through our concrete basement floor in several large spots. A thick white crust develops on the perimeter of these wet areas. What causes this and what can be done about it?

A: The crust is minerals that have leached to the surface as the result of the seepage — a process technically called efflorescence that occurs on many types of masonry. The minerals are basically harmless and often can be removed by scraping and brisk brushing with a stiff-bristled brush. If a residue remains on the floor, scrubbing with TSP should help remove it. TSP (trisodium phosphate) or phosphate-free substitutes are sold at many paint stores and home centers. Muriatic acid also is sometimes used to clean up difficult efflorescence, but I don't recommend it for do-it-yourself use.

Q: The caulk around our bathtub turns black in spots from mildew. How can the stains be removed?

A: Here is a system that always works for me: Soak strips of toilet tissue in chlorine bleach and wad them up to form narrow pads. Place the pads on the mildewed areas and leave in place overnight. When you remove the pads, the caulk should be sparkling clean. Rinse the treated areas with clear water.