When one of the world's oldest trees, the General Sherman, was threatened by the KNP Complex Fire in Northern California, the U.S. Forest Service knew exactly what to do.
It rolled out some giant aluminum foil to wrap the base of the tree to protect it from the flames. The Forest Service has been using these foils for the past 25 years or so.
"We wrapped the foil very similar to when you wrap a baked potato," said Stan Hill, the Forest Service deputy forest management officer.
The idea behind the foil is to protect structures — and yes, sometimes trees — in places where it might not be safe to leave people or resources at that location, he said.
The foil is made by FireZat Inc., which is headquartered in Del Mar. But the company's warehouse is in Denver, Colorado. That’s because it’s a centralized location to quickly move the product to where they’re needed in the fire-prone western U.S.
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The foil comes in rolls of 200 feet by 5 feet wide. And it's not your typical kitchen foil. These are backed with carbon fiber and Kevlar. It works by radiating heat away from the structures (and trees) you're trying to protect.
Wood combusts at around 500 degrees, FireZat CEO Dan Hirning said. But the foil keeps things well below that.
We've done laboratory tests on it, exposed it to 1200 degrees of heat for 10 minutes and the temperature behind the wrap only got up to 212 degrees," he said. "After 20 minutes, the temperature only got up to about 248 degrees, and that's far below the 500 degree, which is what we really want to protect from."
The last time the Forest Service had to use the foil locally was in the 2013 Chariot Fire in the Cleveland National Forest, Hill said. It was used to protect a historic cabin.
"There was an old district ranger cabin, historic cabin that was wrapped in foil," he said. "And that cabin is still there today."
The wrap gives the Forest Service some flexibility to protect structures, historical articles and other valuable things in the forest during a fire, Hill said.
In all, it took a crew of around three to four people around 45 minutes to wrap the small cabin, he said.
Hirning said that's the idea — a crew of around three to four people could wrap a decent size cabin or home in a couple of hours. Though he said it's too late to start wrapping once the authorities have issued an evacuation order.
The wrap is designed not to tear, but can be easily cut into size with a utility knife or scissors.
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While most of Hirning's customers are government agencies, such as the Forest Service. He is starting to see more and more residential customers — mainly those with remote cabins and summer homes.
For residential customers, Hirning said his foil works best in rural areas. That's because the foil wrap will burn if the fire lingers, whereas a forest fire will quickly move through an area.
