New Canaan Fire Marshal: Spontaneous Combustion

[Paul Payne is the New Canaan fire marshal.]

Last week, a New Canaan residence experienced a fire caused by spontaneous combustion.

A recent scene of spontaneous combustion in New Canaan. Photo courtesy of NCFD

The spontaneous combustion, or spontaneous ignition in this case, happened after an employee applied an oil based product to outdoor wood furniture. Upon completion of the day’s work, the oily rags, sponges and brushes were placed in a plastic bucket in the corner of an outbuilding on the property. When he arrived to complete task the following morning, he found the entire area burned and charred from floor to ceiling.

Spontaneous combustion most often occurs when a flammable material (oil, stain, gasoline or other solvents) comes into contact with a combustible object such as a rag, towel or drop cloth.

The actual definition of spontaneous combustion  is “the outbreak of fire without application of heat from an external source”.

Spontaneous combustion begins when a combustible object is heated to its ignition temperature by a slow oxidation process. Oxidation is the chemical reaction involving the oxygen in the air, gradually raising the inside temperature of something (like a pile of oily moistened rags, sponges and paintbrushes) faster than the heat can dissipate to the point at which a fire starts.

Some common offenders are:

• Linseed oil and other drying oils
• Wood stain
• Alkyd enamel resins
• Motor fuel
• Oil based products such as primer, sealer, paint, white pigmented shellac, paint thinners, turpentine, mineral spirits and denatured alcohol.

How to avoid disaster:

• Do not ball up, pile, stack or fold any rags, sponges or similar that are wet due to contact with solvent based materials.
• Do not toss used rags into a trash can or plastic bucket
• Safely store paints and solvents.  Paints and solvents should not be stored near heat generating equipment.

Solvent moistened or wet cloths, rags, drop cloths, work clothes, etc. should be handled as follows:

• Immerse items in water in a metal container with a tight-fitting lid
• After soaking in water, allow items to dry by laying flat on a non-combustible surface (i.e., driveway) away from buildings or other combustible items
• Once dry, items can be safely discarded.