Scrape Off
Photo: David Carmack
As the general contractor for This Old House, Tom Silva seems to be in a constant fight to liberate houses from the grip of old paint. Among his more recent battlegrounds were the TV show's 1997 project house in Milton, Massachusetts, where 18 rough, peeling layers, many containing lead, obscured details of an interior staircase and encased the original clapboards; the 1998 project house in Watertown, Mass., with its paint-clogged mantels and doors; and the 2000 project house in Charlestown, Mass., where some of the exterior brick had been buried beneath a mishmash of latex, milk, and lead paints. In each case, Tom turned to chemical strippers, formulations that dissolve the chemical bonds in a coating so that it can be scraped away. "They're like magic," he says. "You brush or spray a stripper on and scrape soft paint off, sometimes several layers in one stroke."

Chemical stripping is one of the four ways Tom can get rid of old paint. One is to rip out the old material, paint and all, and replace it with new, but sometimes that doesn't make sense. "A piece of wood that's solid walnut or gum would be very expensive to replace, especially if it has a special profile," Tom says. And some details, like the intricate, carved gable detail in Watertown, are irreplaceable. Power sanding is the fastest removal method, but also the one most likely to damage the underlying surface and blow dust into the air, a serious hazard if the paint contains lead. Softening paint with heat guns is a gentler approach, but the process is tedious, often chars the wood, and can create toxic aerosols if the paint contains lead. Stripping with chemicals is also slow and messy, but done correctly it's the surest way to eliminate paint and preserve the wood. "I'm a firm believer in stripping, under the right circumstances," Tom says.

The first and perhaps biggest challenge is figuring out which chemical stripper to use. Buyers have to consider a number of factors, including the amount and kind of material being stripped, the type of surface the stripper is applied to, how quickly and effectively it works, and what gear is needed to use it safely. The starting point for making an informed decision is to look at the ingredients. All strippers contain one of five basic paint-softening substances: solvents such as methylene chloride, N-methyl pyrrolidone (NMP), dibasic ester (DBE), and acetone, toluene, and methanol (ATM); and highly alkaline caustics such as lye. Each one has its strengths and weaknesses, and each one—even if promoted as "safe"—needs to be treated with caution. "They're all potentially hazardous," says Ken Giles, a spokesman at the U.S. Consumer Product Safety Commission (CSPC). But, he adds, the Commission has concluded that all strippers being sold to consumers can be used safely. "If they could not, we would have to ban them."

Ask TOH users about Painting

Contribute to This Story Below

    More in Painting & Finishes