A tractor-trailer hauling hazardous materials was engulfed in flames Thursday on the westbound Thruway in the Town of Sheridan in Chautauqua County, State Police said.
The trailer contained sodium silicate powder, State Police said.
The rig was in the right lane between the Silver Creek and Dunkirk exits, officials said. At 2:20 p.m., authorities said all westbound lanes between Exits 58 and 59 were closed.
But the scene was all clear at about 4 p.m., according to the Fredonia Fire Department.
The fire, reported at 9:56 a.m., burned the cab and trailer. Just before noon, police said that flames were no longer visible on the vehicle.
Authorities weren't sure what caused the fire, but said there was no crash or collision. No injuries were reported.
There was no public health threat outside the accident scene, a State Police spokesman said.
Jason Benedict, an associate professor of chemistry at the University at Buffalo, said sodium silicate is called water glass.
"I don't work with it, personally, but we work with some chemicals that are used producing this stuff and... it's varying lengths of silicon and oxygen, sort of polymer, which SO2 is what glass is made out of," Benedict said.
"What's interesting is it's soluble in water. Obviously, glass is not soluble in water, but this stuff is," he said.
The chemical is used in various applications, including as an adhesive in cardboard.
"With anything that's burning that can get into the air, it's never a good idea to breathe the stuff in," Benedict said. "But I wouldn't say it's acutely toxic or anything like that, but certainly the chemical is caustic and could give you a chemical burn if it settled on your skin."
Firefighters would be unlikely to apply water to burning sodium silicate powder, because that might help the chemical spread, Benedict said.
If the chemical is exposed to acid, it will turn into glass, he said.
"That's normally how this can be cleaned up," Benedict said, "is you add a dilute acid and it basically turns into glass and then you clean it up."
The Department of Environmental Conservation was notified, police said.