Why plaster cracks; restoring porcelain, installing siding

Q We recently installed a clock thermometer in our church which keeps the interior temperature at 50 degrees F. when the church is not in use and turns it up to 70 degrees when it's occupied. Will there be a problem of plaster cracking from these temperature fluctuations?

Paul R. Guenther, Hamburg, N.Y.

I can't imagine that such modest temperature variations will have any effect on the plastered walls and ceilings in the church. Of course, this assumes the lath and plaster work was done with quality materials and workmanship.

Cracks in plaster are more apt to occur from stresses in the framed skeleton of the building than in such relatively minor temperature changes.

If the building is new and of frame construction, it may develop some cracks during the first four seasons of responses to temperature and humidity differentials, but if the structure has undergone these cycles without plaster cracks, the addition of the clock thermostat should trigger no significant stress on the plaster.

Simply, the plaster should not crack unless there are stresses from a seismic or foundational irregularity or drasticm thermal extremity. The temperature variation you mention is hardly extreme.

Q Is there a way to restore or make more presentable a porcelain bathtub, the finish of which has been abused by an abrasive cleanser? We do not wish to replace the tub.

Kent Rodebaugh Derby, Kan.

In the Yellow Pages of the telephone directory, under the title of "porcelain repairs," find a local firm that is experienced in the craft. Another source may be found at your local public library. Look in the Thomas Register under the same general heading.

One porcelain-repair process is Klenk's Tub & Tile, made by Zynolyte Products Inc., 18915 Laurel Park Road, Compton, Calif. 90220, phone (213) 604-1333.

It is a two-part epoxy mixed in equal portions before use. Two coats are required.Observe time and temperature limitations as labeled. Crucial to a successful application is the proper preparation of the tub surface. Be sure to read and carefully follow the instructions on the label.

Anyone wishing to have a porcelain surface refinished by a professional may contact a local franchiser of Porcelite Enterprises, 14650 Southlawn Lane, Rockville, Md. 20852. The phone number is (301) 340-6933. There are other companies as well; again, check the phone directory.

Avoid abrasive cleaners on existing new or restored porcelain.

Q What is the long-term advisability of installing aluminum siding on a clapboard summer home? We used to repaint every 8 to 10 years, but now it is much more frequent, since we had the walls and ceiling insulated to reduce fuel bills. Should be clapboard be painted before the aluminum siding is installed? The siding salesman says no. How do we protect the exposed wooden window and door frames after the new siding is applied?

William B. Patrick, Indianapolis

I agree with the salesman: There is no need to paint the clapboard prior to installing the aluminum siding. As to the exposed wood frames, the siding manufacturer should provide prefabricated metal molding which, when caulked, should protect the frames. Repaint any other exposed wood portions of the windows and doors. Ask your siding contractor to show you how he intends to cover the edges or ends at the window and door jambs to keep them dry.

Many an exasperated homeowner, tired of the frequency and cost of repainting wood siding, has happily covered the exterior walls with low-maintenance metal or vinyl siding.

To the real estate editor:

In the Monitor of Nov. 18 there appeared a question from Mrs. Barbara H. Seaman of Harrisburg, Pa., saying that she wanted to paint her brick house white.

Some 15 years ago I painted my brick house white, and it has never peeled. My house had an overhang, and the rain kept the paint clean.

I used Montgomery Ward's white acrylic paint. I had a small house, 4 1/2 rooms, and it took about a gallon of paint for each side of the house. I didn't use a primer or anything else. I used a brush and roller, the roller for the bricks and the brush to fill in, if necessary.

I like the paint and it was an easy job. I did the work myself.

Mrs. Vesta P. Bishop, Homewood, Ill.