B.C., Westwood

A. I'd think twice about stripping that gilt. Gilt is gilding, which is defined as covered with gold leaf. In fact, it might indeed be gold leaf, which would make the mirror more valuable than if it were stripped, especially if it is antique. That gold leaf is likely to resist all kinds of chemicals; after all, it is gold, which is a soft but very tough material; the gold leaf (much thinner than the sheerest tissue paper) stood up on the State House dome for 30 years.

If you don't know how old it is, take it to an antiques dealer (a scrupulous one, of course) who could give you an idea of its age and value.

If it is gold paint or anything other than gold leaf, it should strip quickly, but you still have to deal with the gesso, which is the base for gold leaf, and often is plaster of Paris, applied to the wood frame and sometimes carved to create a more elaborate frame. In other words, if you were to strip the plaster, you'd have a plain, unfinished, uncarved wood frame.

But one more thing: If it is just gold paint (not gold leaf) and not antique, leave it alone and enjoy it or paint it. If you find it is antique, take it to Channel 2's ``The Antiques Roadshow,'' when it's on location in this area. It might not be worth a lot, but it would be fun to see what it's worth.

Q. I'd like to repair the back side of an old mirror, but the law says you can't use mercury for this purpose. What can I use to make the mirror more reflective? There are a few blemishes in the backing.

R.R., Haverhill

A. I always thought that resurfacing the back of a mirror was with silver. If the mirror is quite old and valuable, or of historical interest, it is best left alone. If it is not any of the above, the best repair is resilvering.

But here are two tricks you might try: Tape shiny, smooth aluminum foil on the back of the mirror, over the blemishes. Then reapply the backing to the mirror, if any; if not, make sure the foil pushes against the back of the mirror. The aluminum will reflect images and the patch might be invisible. The Handyman has been preaching this for years, and he finally a tried it himself; and you know, it didn't work very well for him.

Another trick would be to remove all silvering with a chemical paint remover, then buy an inexpensive mirror of the same shape and install it, mirror side against the glass of the old mirror. Now you'll get unblemished reflection and keep your old mirror.