Question - When stripping wallpaper, I ran into some Homasote, and I learned quickly that you can't take paper off that stuff. Now what can I do? I'd like to paint those walls, but can I paint wallpaper? Dan Sullivan, Natick, Mass.
Answer - Indeed you can't take paper off Homasote, which is essentially compressed papier-mache, especially if the Homasote was not painted before the paper went on. Homasote, which comes in 4-by-8-foot and 4-by-6-foot sheets, is pretty good stuff for application on ceilings and walls, but not those you want to wallpaper. It is relatively soft, and unless it has been painted before papering, taking off that paper is impossible. But never fear, you can paint the paper. Whether the paper is vinyl-coated or not, apply a coat of latex enamel undercoater, and finish with flat or eggshell-finish latex wall paint. Two coats of finish are likely to be needed. Don't try to cover with one coat; it just doesn't work very well and you end up putting on the paint too thickly, which is a sure way to cause peeling.
Question - My front brick steps are deteriorating. Some are cracked, some are broken off. Others are missing their mortar. How can I fix them? M.L., Sharon, Mass.
Answer - That's quite an order, but it can be done. The cracks, if they are hairline and the brick itself seems intact, can be treated with several coats of masonry sealer, sold in hardware stores. This may be enough to fill those cracks, which should be done because water gets into them, and in winter the water freezes, expanding and breaking the brick.
For a broken brick, if you have the broken-off part, you can glue it back together using construction adhesive (Liquid Nails is one brand that comes in a caulking cartridge). This adhesive is weatherproof and will hold the brick together for years, and can fill the joint between the two pieces.
For a brick beyond repair, the only cure is to chip it out and put a new brick in its place. For deteriorated mortar, the treatment is to chip it out of the joint as deeply as practical, and put new mortar in the joint. You can buy a mortar mix in hardware and building stores. The secret to success in filling the joints, called repointing, is to compact the mortar as much as possible; if this is not done, the mortar will fail before the snow flies.
Question - Quite a bit of mortar was left on the bricks I had repointed. How can I get it off? I know I can use muriatic acid, but how soon after the mortar is installed? And what ratio of muriatic acid to water should I use? Richard Johnson, Brockton, Mass.
Answer - You're right; muriatic acid is the only thing that will remove the mortar, because the acid attacks the lime in the mortar. You can use the acid one day after the mortar is installed, or 10 years or 100 years later; it doesn't matter. The ratio is one part acid to one part water. When mixing acid and water, always pour the acid into the water; if you do it the other way the water will splash in the acid, scattering it, which is a hazard to your health. And, when working with acid, always wear skin and eye protection.
Question - I scraped off some moss growing on my slate roof. Is there any way to keep it away? Will it hurt the slate, which is quite old? Ted Minchen, Rockland, Mass.
Answer - There may be no effective way to keep the moss from growing, although once you remove it it might not grow again. Moss on a slate roof will not hurt the slate, but if it grows on wood or other organic materials, it can cause decay. To try to keep the moss from coming back, treat the slate where you remove the moss with one part bleach and three parts water. This bleach treatment also will not hurt the slate.
Question - When my brother bought a gazebo, he was told to prepare a foundation first, putting in concrete piers 4 feet into the ground. We started to dig holes for the piers, but after 2 feet we ran into water (the property is near a pond). Now what do we do? Joe Cohen, Winthrop, Mass.
Answer - That water you hit is the water table, which can go up and down with the seasons. You could do one of several things to get around that problem: 1. Pour the concrete piers 2 feet down, providing plenty of crushed stone under them. This is the worst of the solutions, because frost in winter could heave those piers out of the ground, or at least move them enough to put the gazebo out of level. 2. Drive 4-by-6 pressure-treated posts 4 feet into the ground and set beams on them as a base for the gazebo. 3. Set pressure-treated beams directly on the ground as a base for the gazebo. I think the last two suggestions are the easiest, and considering the high water table, the best way to go.
Question - How can I get rust stains off a concrete floor? Ruth Cutler, Newton, Mass.
Answer - Mix 4 ounces oxalic acid in 1 quart warm water, pour this solution on the stains and let dry. When the solution dries, the oxalic acid crystals may reappear, in which case you sweep them up and throw them away, carefully, because the crystals are toxic. Repeat if necessary.