Although window screens and screen doors today are much more maintenance-free than they used to be, most still require periodic cleaning and occasional repair.

Screen wire or mesh may be metal (aluminum or copper in most cases), but whatever the material, the mesh collects dust and dirt that can cut down considerably on its ability to admit light and air. That is why at least once a year -- and even more often -- screens should be thoroughly cleaned.

Cleaning metal mesh helps slow oxidation or corrosion because dirty metal oxidizes faster than clean metal. The homeowner can use a metalcleaner or polish to remove any buildup or oxidation that has already occured, and possibly to coat the metal to prevent future oxidation.

The best way to wash window screens and doors is to lay them flat on a paved surface (such as a walk or driveway), hose the screen thoroughly, then scrub the mesh and frame with detergent solution, using a long-handled brush with soft bristles. Rub lightly on one side, flip the screen over and do the same on the other side, then stand it against a building or fence and hose it completely.

If the wire mesh is aluminum, and if there is a buildup of white oxidation on the wire, this can be removed with aluminum jelly or metal cleaner. Scrub it on, allow it to stand for about 10 to 25 minutes, then rinse it off with water. This same type of aluminum cleaner and polish can be used on the metal frames of aluminum screens if the surfaces are pitted or oxidized. Painted screens (of wood or metal) can be painted at the same time if the old finish is starting to go.

Torn or punctured screen wire should be repaired promptly. On plastic mesh small puncture or tears can be repaired with clear household cement or clear silicone adhesive. Use a pencil point or similar tool to align the torn fibers as best you can, then dab on a little of the clear cement or adhesive to hold them in place and to fill any openings that are not covered or closed by the replaced fibers.

Larger cuts or tears can be repaired with clear silicone rubber, but if a piece is actually missing, a patch will be needed. Cut a piece of mesh for a neat fit, then cement it in place to cover the hole. The neatest job will result if the patch just fits inside theopening with adhesive used around the edges to hold it in place, but it will be simpler to apply the patch if you cut it oversize and overlap it before cementing in place.

In metal screen wire, very small holes and punctures can also be patched with clear cement or adhesive, but in most cases a patch will be needed. Ready-made screen wire patches are available in many hardware stores, or you can cut out your own from the extra piece of the same kind of mesh.

Cut the patch slightly oversize, than unravel a few strands of wire around all four sides and leave the other wires sticking out. Bend these protruding wires at right angles to the patch and push them through the existing mesh as you press the patch into position. The wires can then be bent over in back to hold the patch firmly in place.

When the wire or mesh is so badly torn or corroded that cleaning or patching is impractical, it is time to completely replace the screening. As a rule, Fiberglas is easier than aluminum to handle and install, and in most cases costs less.

In addition, with Fiberglas you have the choice of using one of the energy-saving solar types that also provides a certain amount of shading and protection against the absorption of solar heat in the summer. This type costs more, but it reduces the use of air conditioners by helping keep the inside cooler on sunny days, and also helps reduce glare -- though it does cut down on visibility to some extent.

Fiberglas comes in rolls of various widths, so buy a width at least six inches wider than the largest size screen you have to cover. Measure the length (height of each screen), then total the footage you will need, adding about six inches to each to allow for waste. On a screen with a wood frame the mesh will be held in place by tacks or staples, on a metal screen by a plastic or metal spline that fits into a groove.

On wood screens, start by laying the screen flat and prying off the moldings that cover the edge of the old screen wire. If you do this carefully, you should be able to use the moldings again. Pull out all tacks or staples that hold the old wire in place, then scrape the surfaces clean. Use metal mending plates or corrugated fasteners to reinforce loose joints or weak corners.

Start to install the new mesh by folding a narrow hem at one end stapling this down across one end of the screen frame. As a rule, the neatest job will result if you drive the first staple in at the center, then work out toward the corners, smoothing the mesh as you go to avoid wrinkles. Next, stretch the mesh tight along the length of the frame, then fasten it down at the other end. m

One way to stretch the plastic mesh tight is to grasp a handful of the excess and pull it tight over the far edge with a sort of rolling downward motion while you staple it down with the other hand. Another method is to prop up each end of the frame on a piece of 2-by-4, then use clamps to press down on the middle of the frame.

This will bow slightly so after the mesh is secured at each end, removing the clamps will allow the frame to straighten and draw the mesh tight along its length.

Either way, staple the other end the same as you did the first, working from the center out to the corners, then fasten the mesh down along both sides of the frame. Replace the wood moldings (or install new ones if the old are badly split), then use a sharp knife to trim off all excess that protrudes beyond the moldings.

On metal screen frames the mesh is held in place by a metal or plastic spline that fits snugly into a groove or track, so again the mesh must be slightly oversize on all sides. Special rollers or wheels are sold to press the spline into place, although a screwdriver can be used if you do not have much to do (the roller or wheel is much faster).

Fasten one end in place first, then stretch tight and fasten the other end down. Do the sides last. Excess can be trimmed off, with a sharp knife or a pair of scissors after all the splines are down.