It is a fire hazard we keep hearing about in america from a very common product. A week ago it happened at a restaurant. It happened at a home. Fire starting without even a spark and the cause, lynn... See More
It is a fire hazard we keep hearing about in america from a very common product. A week ago it happened at a restaurant. It happened at a home. Fire starting without even a spark and the cause, lynn seed oil, the oil used to preserve wood. It can happen in a split second and abc's elizabesabeth leamy sends out an alert tonight. Reporter: They were caused without a spark and the flames started by themselves. It is the danger of lynn seed oil, a wood sealant found in every hardware store. We're going to show you how it happens. Causing some linseed soaked rags and newspaper into a box. That is exactly what mike and sherry prentiss of cincinnati did. I had put it sort of folded on itself into a corner of the garage. Reporter: Suddenly they were fighting for their lives. The flames were shoot 30 feet into the sky. Reporter: In our experiment after just an hour, the linseed-soaked rags have reached 110 degrees. Two hours in, we spot smoke. Linseed oil is safe for wood because you spread it out. But left up on wadded up rags or paper, it is so concentrated it heats up as it evaporates. Some experts say take linseed-oil soaked rags and spread them out on your driveway until they are totally dry. Want to be even more cautious, get a metal can, fill it up with water, dump the rags in and seal it up. It's been a little over three hours now and suddenly we see flames. Whoo! And remember all with no outside spark. Elisabeth leamy, abc news, washington.
This transcript has been automatically generated and may not be 100% accurate.