Q: I have some hard paint brushes that I did not take care of. Is there any way to soften them up and make them usable again? - N.F., Fitchburg, Mass.

A: Most paint and hardware stores sell special brush cleaning solutions that are specifically designed for hard brushes. Following the directions on the can, you soak the brushes in the solution for time required to soften them, then wash thoroughly in a detergent solution.

Comb the bristles flat, then wrap tightly in paper to preserve the shape when the brush is completely dry.If you can't find one of these liquid brush cleaners locally, then you also can soak the brushes in paint remover, but take them out as soon as they are soft and wash them thorougly in solvent to get rid of all the remover.

Q: I recently moved into a house that has slate floor in several rooms. These floors had heavy accumulations of wax that I am having difficulty removing. I have mopped many times with various household detergents and with bleach, with only limited success. I finally tried muriatic acid, which appears to be doing the job, but the grout areas still retain an ugly residue. Have you any suggestions about how to treat these floors? - C.T., Pittsburg, Pa.

A: Any commercial wax-removing solution will be easier and safer to use than muriatic acid, and will probably work better. Most have to be used hot, so follow directions for full effectiveness. In most cases the job will be hastened by scrubbing with a stiff brush, or even with fine steel wool.

Q: One of the faucets in my bathroom squeaks every time it is turned on or off. Do you know how this can be remedied? - E.K., Garden City, N.Y.

A: If the faucet is working except for the noise, chances are lubrication will do the trick. I suggest trying a penetrating lubricant spray. Squirt a little around the threads of the faucet stem, then open and close it a few times. If this doesn't work, you will have to shut off the water and take the faucet apart to spread some waterproof grease around the threads.

Questions about home repair should be addressed to Bernard Gladstone in care of The New York Times Syndication Sales Corp., 200 Park Ave., New York, N.Y. 10017. Questions of general interest will be answered individually. CAPTION: Illustration, no caption, By Mary Myers for The Washington Post