Q: I have a new home with a brick chimney that has been badly stained by soot. This happened because the furnance was not properly adjusted originally (it is now fixed). What can I do to remove the soot discoloration on the outside? It is visible from the front of the house.

A: Depending on how bad the stains are, and how deeply embedded, they can often by scrubbed off with a strong commercial detergent. Use one of the powdered solutions sold in paint stores for commercial or industrial use. Scrub with a stiff brush, then flush away with water.

If this doesn't do the trick, your best bet is to try to get a sandblasting contractor to do the job, or rent sandblasting equipment that will let you do the work yourself.

Q: We have heating ducts running through a crawl space under our house and we use this space for some storage. The large main duct is covered with insulation, but the smaller ones leading up to the various rooms are not covered. Would it help to insulate the smaller ducts, or is it advisable to leave these uncovered so they can help keep the area dry?

A: The uncovered ducts definitely radiate some heat into the crawl space area, and thus most likely do contribute to keeping that storage area dry. Covering these ducts with insulation (if you can reach most of them along most of their length) will help to conserve fuel by cutting down on the heat dissipated into the crawl space, but whether this will contribute to a dampness problem there no one can say. If the crawl space has a paved floor, and if it is properly ventilated, then there should be no problem -- but it is hard to say there definitely won't be any.

Q: We have slate on the front steps, which we painted with a clear sealer. Now this sealer is constantly peeling in spots and this makes the steps look messy. We tried removing the sealer by scrubbing with a stiff brush, but this hasn't taken it all off. Do you know of anything we can use to remove the sealer so we can start over?

A: You should be able to get the sealer off with paint and varnish remover. Use a water-washable type; this will permit you to wash the residue off with them. Let it flow liberally off the brush and allow it to soak for 10 to 15 minutes, then scub it off with a stiff brush dipped into water and rinse clean.

Q: We recently acquired a large, antique mirror with a solid oak frame. The frame is in excellent condition, but the mirror has several worn spots where the reflective coating has worn off. How can this be repaired?

A: You really cannot repair something like this yourself. The coating on the back of the mirror is a plating (actually several different layers), so redoing this is seldom practical. It is usually simpler to have a new mirror cut to fit and installed in the frame. Most companies that sell glass and mirrors can handle a job of this kind for you.

Q: The discharge pipe from my dishwasher is apparently partially clogged, because each time the water is expelled from the machine some of the waste water leaks out of the overflow opening onto the counter top. Is it safe to use a liquid drain opener in this pipe?

A: Although I cannot say for sure, I would avoid these compounds because they can damage some plastic and rubber seals that my be inside the machine. The discharge comes through a flexible rubber hose that is attached to the waste pipe on the kitchen sink. The best way to check it is to disconnect it at the sink end and see if it is clear (poke a wire snake through).

The clog could be inside the sink drain instead of in the hose, since a clog in the drain will obstruct the flow enough to cause it to back up into the overflow opening. For this you can use a chemical drain opener.

Q: A tenant has been using the basement of my son's house as a machine and auto repair shop for old cars. Oil from the motors and other parts has soaked into the concrete basement floor, and into the asphalt tiles that cover an adjacent recreation floor. Is there any way to get the oil out of these floors, or is there any way to seal and then paint them?

A: You should be able to remove most of the oil from the concrete by using a special liquid sold for this purpose (usually referred to as driveway cleaners) in most lumberyards and hardware stores. If there are heavy accumulations that have been there for some time, however, I doubt if you will be able to get it all out. You may be able to apply a sealer and then paint over it if there is no dampness problem in the floor. Check with your local paint store about a sealer for concrete floors.

You may have to treat the floor with muriatic acid solution first, if this is recommended by the manufacturer. Either way, first test the sealer on a small area to see if it really works.

If it does, you will then be able to paint over it with latex deck enamel. As for the asphalt tile, I'm afraid this is hopeless: Once asphalt tile is oil-soaked, all you can do is rip it up and replace it with new material (you may still need a sealer before new tile can be applied).