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Lead Paint Is No Match for Blinding Rays

Light pulses may strip lead paint more efficiently than scrapers and solvents can
lamp



Phoenix Science and Technology
Intense pulses of light may be just the thing for stripping toxic lead-based paint from homes and buildings. Researchers at a small Massachusetts company report they can vaporize lead paint off of surfaces using a lamp that emits short but powerful bursts of light.

"We're trying to get away from the mess and toxicity of a chemical stripper and not create all the dust of a mechanical method," says Michael Grapperhaus, senior scientist at Phoenix Science and Technology in Chelmsford, Mass.

Grapperhaus and his co-worker Raymond Schaefer tested a device they call a surface discharge lamp, which consists of a cylindrical quartz tube inside a vessel full of xenon gas. When they send a high voltage pulse across the tube, it heats the gas inside into plasma and in turn produces an intense light pulse. A vacuum removes the resulting paint vapor and a rotating brush sweeps up the residue.

Six pulses were sufficient to strip two coats of dark green lead paint from a wood surface, which emerged unscathed, the researchers report in a paper published online November 15 in Environmental Science and Technology. The pulse is brief enough that it does not create significant heat, Grapperhaus says.

The method reduced the concentration of lead from 1.7 milligrams to 0.3 to 0.4 milligram per square centimeter, below the legal limit of 1 milligram. The lamp worked similarly on a steel surface, and air samples collected during the paint stripping tests were unable to detect significant traces of lead wafting from the samples, they report.

In many cases property owners end up covering lead paint with a sealant or another coating because of the potential hazards of removing it, says Wayne Schmitz, director of technical services at Flash Tech, Inc., of Hazelwood, Mo., a funder of Phoenix's work. "With this technology it may actually be possible to remove lead safely instead of covering it over," he says.

Some unknowns remain, however, including the speed at which the system would operate and whether it could effectively strip paint from tight corners and crevices, Schmitz says.

Flash Tech hopes to adopt the technology, he explains, because it is much gentler than the company's existing light pulse system, which strips paint but generates heat and leaves a sticky black residue.

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