Many a fine piece of old furniture has been laboriously stripped and refinished when the job wasn't really necessary. The result is a waste of time, energy and money, not to mention the loss of authentic charm.

In many cases, all that work can be avoided simply by cleaning the old piece carefully. Years and years of sitting in an attic or the dark corner of some basement can cover a piece of furniture with a dingy film of dust, grime and mildew.

Before you try paint remover, try a solution of warm water and detergent. If the piece is solidly built, attack it with a scrub brush. If it is more delicate, use a soft damp cloth so you don't oversoak it and loosen joints and veneers. Then rinse with rags dampened in clean water and wipe dry.

If the piece is especially dirty, a stronger treatment may be called for. Combine a quart of hot water, three tablespoons of boiled linseed oil and a tablespoon of turpentine. Scrub with this solution on a rag.

Once you get a piece clean, you may discover that the finish is sound but has a few small defects you may be able to fix, such as white rings, cloudiness and dullness.

Dullness. If an old dull varnish finish is soft and gummy, there's not much you can do short of removing it. But if the dull finish is still hard, try this: Combine two parts boiled linseed oil and one part turpentine. Rub this mixture vigorously into the varnish with a rag. Then polish with a dry rag.

White spots. The standard treatment is to rub with a fine abrasive and oil. You can use light machine oil such as 3-in-1 plus cigarette ashes; or baby oil and powdered pumice or rottenstone (paint store items); or an automotive rubbing compound. In any case, rub the stuff over the white spot with a soft cloth and the damage should polish out. Be warned, however, that the treatment may make the repaired area glossier and smoother than the surrounding area. If so, you may want to treat the whole surface.

Scratches. If a scratch is fine and doesn't go all the way through the finish, you can sometimes soften the finish with solvent and it will flow together to fill the scratch. Use a fine artist's brush to dab the solvent into the scratch. Try denatured alcohol first: If the finish is shellac the alcohol should work. If it doesn't, try turpentine: It works on varnish. If neither of these two solvents works, try lacquer thinner. It will do the job on a lacquer finish. Warning: Lacquer thinner is strong stuff and may damage the finish, so test on an inconspicuous part first.