Spontaneous Combustion: The Dangers of Linseed Oil

One of three recent structure fires in South Burlington caused by improperly disposed rags. 

- Photo: WCAX

Spontaneous Combustion:  Dangers of Linseed Oil

            One of the worst high rise fires in U.S. history happened in Philadelphia in 1991.  Meridian Plaza burned for 19 hours, killing three fire fighters.  Investigators found the fire started after workers left behind rags stained with linseed oil in a vacant office. The term “spontaneous combustion” strikes many as one that deals more with magic and fantasy than real life and real tragedies.  Under certain circumstances, a common household product can combust -- or catch fire -- without any outside flame or spark. 

That product is linseed oil, including other oils used in stains which so many people use to treat their wood furniture, fence, or deck this time of year. It's a natural product extracted from flaxseed. Liquid linseed oil in the can is no more hazardous than any other oil. But leftover linseed oil on rags, paper towels and so on has the unique ability to generate its own heat as it dries.  Often times getting so hot that it bursts into flames.

            The name is a little misleading, though.  Spontaneous combustion does not occur out of the blue.  All fires, including those ignited “spontaneously,” require three elements:  fuel, oxygen and a source of heat.  Normally, we think of a source of heat as something with a flame.  There is no flaming ignition with spontaneous combustion.  When linseed oil is exposed to air, it combines with the oxygen molecules causing an exothermic chemical reaction that generates heat.  If the linseed oil is on something like a cotton rag, it can catch fire at as low as 120 degrees -- with no outside spark.  When these same rags are bunched up and piled on top of each other, heat can build up rapidly leading to a fast-moving fire.   

Preventing spontaneous combustion from occurring is as simple as practicing a little routine housekeeping:

·      DO NOT pile oily rags on top of each other

·      Spread oil/finish rags in a single layer on flat ground so the heat dissipates while the material cures

·      Hang oily rags up to dry, preferably outdoors

·      Safely dispose of your stained rags at a hazardous waste collection site

South Burlington Fire Department has responded to three significant structural fires in the last month alone.  Following a thorough investigation by the Fire Marshal, two of the three fires were ruled accidental due to improper discarding of rags stained with linseed oil.  The third fire was ruled accidental due to improper discarding of materials.

Senior Fire Fighter/Paramedic Bradley Dattilio

Fire Prevention Education Coordinator - SBFD