HOME CLINIC; HINTS ON USING ACRYLIC PLASTIC AS A REPLACEMENT FOR GLASS (Published 1983) (2024)

CLEAR sheets of acrylic plastic have been become increasingly popular for use as a glazing material in storm doors, basem*nt windows, garage doors and other hazardous locations around the home where the safety features of a break-resistant plastic are desired to eliminate the potential dangers posed by the use of conventional window glass. (Plexiglas and Lucite are two of the most widely sold brands, but they are not the only ones.)

These plastic sheets are available in many hardware stores and home centers, as well as in stores that specialize in selling all types of plastic products.

In addition to its use as a replacement for glass in windows and doors, acrylic plastic in sheet form is also used for framing and mounting pictures and for making many craft projects and decorative home accessories.

Cutting and working with acrylic plastic is not difficult and requires no special skills or expensive tools. While some dealers will cut sheets to exact size when requested, not all are equipped (or willing) to do this, so the do-it-yourselfer will often find it worthwhile to cut his own.

Knowing how to cut and work with this material will also save money in many cases since full sheets often cost less than smaller pieces and there is no need to pay a cutting charge; leftover pieces can be used for many other purposes, such as covering for small shelves.

Acrylic plastic sheets come in various thickness, ranging from onetenth of an inch up. Generally speaking, thicknesses of one-eighth of an inch or one-quarter of an inch are used for glazing, but the onetenth size can be used for small panels in doors; the thicker the panel, the more break-resistant it is.

There are two methods of cutting the sheets to size: sawing and scribing. In both cases, cutting should be done with the protective paper on each side left in place. In fact, the protective paper should not be removed until all work on the sheet is finished and it is actually installed, except in glazing operations. In glazing, you have to peel the paper off around the edges in order to fasten the sheet in place.

For sawing, either a hand saw or power saw can be used, but in each case a fine-tooth blade is essential for a clean cut (32 teeth per inch for one-eighth of an inch and one-tenth of an inch plastic, and 14 to 18 teeth per inch for one-quarter of an inch). It is important that the plastic sheet be firmly supported while it is being cut, so as to minimize vibration that can cause chipping or ragged edges. When using a power saw, feed the blade in slowly to avoid overheating and melting the edges of the plastic.

For most amateurs, the easiest and neatest way to make a straight cut is by scribing and breaking. Special plastic scribing tools for cutting plastic laminates, as well as acrylic plastic, are available in hardware stores and do-it-yourself centers. As shown in the drawing, these are used to score the surface of the sheet along the line of cut, using a straightedge as a guide. Press down hard on the straightedge to keep it from slipping, then apply firm pressure to the scribing tool and drag it along the full length of the cut mark.

Repeat this, scribing or scoring along the same line at least five or six times for thinner sheets, and about 10 times for one-quarter inch sheets. Then place the scored sheet, face up, over a round dowel at least three-quarters of an inch in diameter. Press down firmly on both sides of the score mark, keeping the hands close together, to complete the break. Move your hands along the score mark as the sheet snaps in two along the scribed line.

Another way to finish the break is to place the scored sheet face up so the smaller piece hangs over the edge of a table or counter while the score mark is directly over that edge. Pressing down smartly on the overhanging side while holding the rest of the sheet firmly in place should snap the sheet along the scribed line - but this works only if the table or counter has a square edge.

After sheets have been cut to size, it is a good idea to smooth the edges and remove any saw marks or jagged edges that may remain - not only for esthetic reasons, but also because smooth edges help to make the sheet more resistant to breakage.

The smoothing can be done in several ways. Many use a fine-tooth file, or medium-grit sandpaper wrapped around a sanding block, but one of the quickest and neatest methods is by scraping the edges with a sharp-edged piece of metal.

For this you can use the back of a metal hacksaw blade, the edge of a razor blade or sharp pocketknife, or one blade from a pair of scissors (illustrated here). The idea is to drag the edge of the metal blade toward you while holding it across the edge of the plastic as shown, with the blade at approximately a 90-degree angle to the edge of the plastic.

Bear down with moderate pressure and draw the metal slowly toward you two or three times. This will smooth off all tool marks, leaving the plastic with a clean edge. For a really satin-smooth transparent finish (on projects where the edges will be visible), further polishing can be done by wet-sanding with No. 400 paper, then buffing with a compound sold for use on plastic.

Answering the Mail Q. My house has steam heat and all windows have storm windows on them. The attic has 3 to 6 inches of insulation on the floor. Despite all this, the house still feels cold when the thermostat is at 68 degrees, especially the second floor. The house is warmest in the early morning when the thermostat is advanced from the night setting of 60 to the day setting of 68. After that it is downhill. Since warm air rises, why is it warmer downstairs than upstairs? -A.E.Q., Hackensack, N.J.

A. My guess is that you have two problems: (1) Sounds as though the walls are not insulated, and that would explain why you feel chilly when the heat is off: the outside walls get cold and body heat is lost to them. (2) Since the house is comfortable for a while in the morning when the heat is coming up and all radiators are hot, chances are the thermostat is downstairs and there is more radiator area (in proportion to living space) downstairs than there is upstairs. The heat goes off when the temperature down there reaches 68, even though the upstairs has not yet warmed up. You may get some relief by having the system balanced so more heat goes to the upstairs radiators than the downstairs ones, but I think your only permanent solution is setting up a two-zone system with a separate thermostat for each floor. --------------------------------------------------------------------- Questions about home repair problems should be addressed to Bernard Gladstone, The New York Times, 229 West 43d Street, New York, N.Y. 10036. Questions of general interest will be answered in this column; unpublished letters cannot be answered individually.