June 10, 2020
Think those oily rags from working on the car or refinishing the deck are harmless? Most people do — and they are dangerously mistaken. Oil-soaked rags can cause some serious damage if they’re not disposed of properly. A pile of oily rags thrown together in a corner of the garage or stored in a box can spontaneously self-ignite.
That’s right — the rags can slowly create heat, ignite on their own and create a fire. The fire can then quickly spread to the surrounding area. This may seem unbelievable except UL and the fire department of Wilmette, Illinois, partnered up for a demonstration.
What kind of oils are we talking about?
First, let’s start with the kinds of oils that pose a threat. Think of the types of do-it-yourself projects you might tackle at home: changing the oil in your car, using oil-based paint primers on cabinets, staining furniture or refinishing your backyard deck. While all oil-soaked rags are a fire hazard, there are certain types of oils, like linseed oil, are more likely to self-ignite. Also, the rags you use to clean up spills and wipe off tools with should be disposed of properly.
Common combustible oils:
- Linseed oil and other drying oils
- Wood stain
- Alkyd enamel resins (a common binder in oil-based coatings)
- Motor fuels and lubricants
- Oil-based products such as primer, sealer, paint, white-pigmented shellac, paint thinner, turpentine, mineral spirits and denatured alcohol
The science behind it
“Rags that are soaked with combustible oils create and release energy and heat,” said Bob Backstrom, fire research manager of Retail and Industrial Research and Development at UL. “When rags are tightly packed in a confined space, there’s an effect of insulating the pile. The energy and added heat can’t dissipate fast enough and the temperature of the oil-soaked rags increase.”
Backstrom continued, “Think of an active child strapped in car seat on a long road trip. The child undergoes an emotional response, energy builds and builds, and eventually it’s so stressed a reaction happens. In the case of a child, they vent by crying and having a tantrum because they want out. With oil-soaked rags, the oils undergo a chemical reaction through combustion creating excessive heat, which ignites into fire. This happens without an external source of ignition, such as heat from surrounding environment or an external flame.”
It happens more than you know
According to the National Fire Protection Association (NFPA), an average of 900 home fires per year are started when oily rags catch fire; Also, an average of 1,700 home fires are caused by instances of spontaneous combustion or chemical reactions.
The steps to prevent fires from oil-soaked rags
If you remember anything from reading this article, let it be these three words: dry, dunk, dispose. Any time you’ve finished with a rag that was used to apply or clean up chemicals or oils, use the dry, dunk, dispose method to discard of them safely. Having a UL safety certified, oily waste container on hand also reduces the fire hazard.
Lay the rags out individually on the driveway, garage floor or sidewalk or hang them out to dry. Provide at least a half of a foot of space between each one. If you’re indoors, make sure there’s proper ventilation. Let the oils dry out. This helps the heat and energy release into the air.
Once dry, get them wet again, this time with water. Dunk each rag individually in a container of water. This could be an empty coffee can, empty paint can or bucket of water. You can also flood them with the garden hose or drench them in a utility sink.
If you used an old coffee or paint can to dunk the rag, discard the oily water. Refill it with clean water, submerge the rag inside and close the top. If you don’t have an old can, fill a resealable bag with water, submerge the rag inside and seal the bag. Then, contact your local garbage facility to find the nearest hazardous waste disposal drop off.
If that was a lot to take in, here’s a video to help you remember the most important parts. Brought to you by UL and the Wilmette, Illinois fire department.
Top Three Tips:
- Remember the dry, dunk, dispose method next time you work with oily rags.
- Dunk each rag individually then remember to dunk them again in clean water.
- Contact your local waste management service to find out where you can drop off oily rags.