Temporary coating may protect homes from wildfires
September 3, 2013
• USDA California scientists come up with the formula
• And you thought corn starch was just for your shirts
Food technologist Artur Klamczynski (left) and plant physiologist Greg Glenn prepare to conduct burn tests.
(ARS photo by Delilah Wood)
Spraying a home with a temporary fire-retardant coating may prevent it from being destroyed by a forest wildfire, according to scientists with the Agricultural Research Service in Albany in the East Bay.
An experimental gel that U.S. Department of Agriculture plant physiologist Gregory Glenn and his colleagues in Albany have developed might offer better, more affordable protection than other fire-retardant gels.
The experimental gel is made of sodium bentonite clay, corn starch and water. According to Mr. Glenn, results suggest that a layer of ge — about one-quarter-inch thick — “may protect wood-based home siding for up to 30 minutes.”
That might be just enough to spell the difference.
“In a best-case scenario,” he says, “all you might have to do is wash the coating off your house after the fire,” Mr. Glenn says.
In preliminary research, Mr. Glenn and his coinvestigators cut planks of residential wood-based siding into squares measuring about 7 by 7 inches by 3/8-inch thick, then coated all but the "control" squares with either the experimental gel, a commercial gel, or other formulations.
In several of the tests that followed, the experimental clay-and-starch gel outperformed the other coatings. "Drying tests," for example, showed that the gel kept its moisture longer, an important quality in a fire retardant.
In "burn tests," siding coated with the research gel took longer to reach 392 degrees Fahrenheit, the temperature at which wood-based siding may begin to burn and char.
Other tests, in which the squares were positioned upright, demonstrated that the gel was less prone to sliding, technically known as "slumping," toward the bottom of the squares. The starch helped the coating stay in place and, in so doing, to shield the siding.
In all, the California studies provide a foundation for more extensive tests of the promising, all-natural coating, ARS says.
Although neither sodium bentonite clay nor starch are new to firefighting, the idea of combining these materials to form a fire-retardant coating is apparently a "first," as is the California team's detailed analysis of the coating's effectiveness.
ARS is seeking a patent for the research.