Q. How do you remove the corrosion on the frames of aluminum screens?
A. First, try one of the soap-filled steel wool pads, preferably one containing a rust arrester. If this fails, use stainless-steel wool size 00 and a solvent type of liquid floor wax, dipping the wool pad into the wax and applying to the aluminum.
As a third option, wet the stainless-steel wool pad with an etching solution made of one part etching chemical cleaner to three parts water.
Cover the wet pad with powdered pumice or some other heavy-duty abrasive.
In scouring aluminum, always rub with the "grain." That is, back and forth, never crosswise or in a circular motion.
Apply to an area small enough to be completely covered and kept wet for three to five minutes. Follow with a thorough rinsing before the cleaner dries on the surface.
When you have cleaned aluminum, protect the surface with an aluminum or automobile wax. Rewax periodically.
Q. How do I remove rust stains from a concrete driveway? I have tried detergent, bleach and a commercial cement cleaner with no luck.
A. Mild rust stains can usually be removed by mopping with a solution containing one pound of oxalic acid powder per gallon of water.
After two or three hours, rinse with clean water, scrubbing at the same time with stiff brushes or brooms. Bad spots may require a second treatment.
For deeper stains, try a solution of one part sodium citrate dissolved in six parts lukewarm water and mixed thoroughly with seven parts of lime-free glycerol, or glycerin.
Make a stiff poultice with calcium carbonate or kieselguhr, which is diatomaceous earth used for polishing. Apply a thick layer on the stain with a trowel and leave for two to three days. Scrape or brush off when dry.
If staining persists, the treatment should be repeated. Wash thoroughly with clear water.
Ammonium citrate can be used in place of sodium citrate for more rapid stain removal, although the surface may be slightly etched.
Another stain-removal method, recommended for particularly deep and intense iron stains, is to saturate a bandage with a solution of 1 part ammonium citrate or sodium citrate in six parts lukewarm water and apply it over the stain for half an hour.
The solution can also be brushed on the stain at five- or 10-minute intervals.
If the stain is on a horizontal surface, follow this treatment by sprinkling it with a thin layer of sodium hydrosulfite crystals, moisten with a few drops of water, and cover with a poultice made of powdered inert material and water.
On a vertical surface, place the poultice on a trowel, sprinkle on a layer of sodium hydrosulfite crystals, moisten lightly, and apply to the stain so the crystals are in direct contact with the stained surface. Remove the poultice after one hour.
The operation may have to be repeated with fresh materials if the stain is not completely removed.
When the stain disappears, scrub the surface thoroughly with water and another application of the sodium citrate solution, as in the preliminary operation. The purpose of this last step is to prevent the reappearance of the stain.
Occasionally, brown iron stains can turn to black when treated with sodium hydrosulfite. This may also happen if the poultice is left on for longer than one hour.
Should the stain become black, treat it with hydrogen peroxide until it is oxidized back to the brown color. The sodium hydrosulfite treatment should then be resumed, proceeding as above.
Unless adequate ventilation is provided, this method should not be used indoors because a considerable amount of toxic sulfur dioxide gas will be emitted when the sodium hydrosulfite comes in contact with moisture. Use proper respiratory safety equipment.
When working with acid mixtures, be sure to pour the acid into water -- not water into acid. Avoiding splashing and wear old clothes, rubber gloves and goggles.
The treatments described here for rust staining are those recommended by the Portland Cement Association.
Send inquiries to Here's How, Copley News Service, P.O. Box 190, San Diego, Calif. 92112-0190. Only questions of general interest can be answered in the column.