Q: I would like information regarding urea formaldehyde foam insulation in walls. We are thinking of buying a house and are afraid of settling on something not knowing if formaldehyde is present.
A: UFFI was installed in most homes during the 1970s but was banned in 1982 by the U.S. Consumer Product Safety Commission for use in schools and homes. The commission banned the material after reviewing test data that linked formaldehyde fumes to cancer in rats and mice. The ban was later overturned by a federal appeals court. By that time, however, most of the contractors installing the material had left the business.
During and after installation of UFFI, formaldehyde levels decline rapidly. Although people vary in their susceptibility to formaldehyde, most healthy adults would not experience ill effects from exposure below 0.1 part per million. And since a house containing the insulation would probably have had it installed years ago, any vapors from the insulation would probably be negligible.
Formaldehyde is widely used in many other products, including plywood, particleboard, chipboard, plastic laminates, cosmetics, cleaners and paper products. It is possible that the air in the house could have a high formaldehyde concentration from these products.
If you are concerned about this, have the air tested for formaldehyde by a certified lab.
Q: My 4-year-old son decided to use the living room wall as a canvas for his new crayon set. I've had problems in the past trying to repaint over stains when I was unable to completely remove them. What's the best procedure for dealing with this problem?
A: Your first impulse may be to try to paint over the stain, but many stains cannot be covered with paint alone. Rust, grease or oil, crayon wax and Magic Marker ink may be activated by the solvent (water or oil) in the paint, and bleed back through the new paint. This is true regardless of how many coats of paint you apply. You must either seal over the stain or remove the offending material from the wall before painting.
It's best to try to remove the stain material. Check with a paint dealer for products containing solvents that will remove splattered latex paints, grease, crayons and other stains. Pour some cleaner on a clean cloth, wet the stain and let the cleaner work for a couple of minutes. If you just try to scrub the stain away, you may also remove some wall paint.
If the stain comes off the paint, spot prime the stain area and then repaint the wall.
If the stain proves difficult to remove, you can seal in almost any stain with a shellac sealer. The shellac is fast-drying, so it does not activate the stain material, but covers it over.
To avoid the shiny spots over the shellac sealer, seal the entire wall with shellac, not just the stain.
To submit a question, write to Popular Mechanics, Reader Service Bureau, 224 W. 57th St., New York, NY 10019. The most interesting questions will be answered.
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