The fourth solvent-type stripper is a combination of acetone, toluene, and methanol (ATM). Like methylene chloride, these highly volatile chemicals can be extremely effective in removing paint, especially when formulated with waxes and thickeners that trap the active ingredients close to the surface. Phillip Pennington, whose Star 10 strippers fall in this category, says these are the same solvents found in cans of high-performance paint, where they keep the solid ingredients in solution. "Our stripper puts the solvent back into the paint, but without turning the coatings to liquid," he says. "It breaks the adhesion or bonds where the paint stuck to the wood." An ATM stripper removed the paint from an old mantel at the This Old House project in Watertown and impressed Tom with its effectiveness. "The stuff was amazing," he says. "We sprayed it on, left it overnight, and by morning it had taken the finish right off."

Yet according to the manufacturer's material safety data sheets, if inhaled or absorbed through skin contact, ATM strippers can irritate the eyes and skin, damage the lungs, liver, kidney, and heart, as well as the central nervous and reproductive systems, and can be fatal if swallowed. They need to be used with plenty of ventilation and the proper safety gear, including splash-proof goggles, butyl or plastic-laminate gloves, and a respirator fitted with organic-vapor cartridges. These strippers are also highly flammable—cigarettes, pilot lights, and sparks from electrical equipment can set off an explosion if the vapors concentrate sufficiently.

The only fumeless way for consumers to remove paint is with caustic, or alkaline, strippers. Made with caustic soda, lye, or potash, they eat through many layers of coatings the same way lye-based drain cleaners dissolve the gunk in a clogged pipe. This slow but steady chemical action is remarkably effective, but once the paint is gone, alkaline strippers don't stop. They'll darken and desiccate exposed wood and will attack the new finish unless neutralized with an acid rinse. Skin and eyes are equally at risk, making goggles, chemical-resistant gloves, and protective clothing essential for anyone applying or removing the stripper.

Because it's hard to know how deeply and uniformly the neutralizer has done its work, repainting is a gamble. "I usually stay away from alkaline strippers on wood," says Dee, "except on decks or places where I can rinse the area with plenty of water and an acid." Everywhere else, he uses methylene chloride when he's in a hurry and a thick NMP stripper when he has more time. Then he steps back and moves on to the phase every painter loves: applying a fresh finish.
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