When we arrived at the house to surf this morning there was something odd about the way my dad was acting, like he had something to say, but I couldn't quite put my finger on it. Then he casually said, "So, what do you guys know about spontaneous combustion?". "Oh my gosh, what happened!?" was all I could say. Spontaneous combustion was something I thought of as a fake thing from horror movies where people caught on fire (weird, I know). He had prepared a presentation for us and I could tell he wanted to see this presentation through, so he didn't reveal what had happened just yet.
I knew it was serious when he pulled out his i-pad and began educating us on the subject, though he didn't seem upset. He just appeared ready to teach us a lesson. Despite my panicked questioning, my dad calmly continued reading the definition of spontaneous combustion off and explaining the types of materials that can cause it. After a few minutes that seemed like a day and a half, he led us to the garage where we saw it. The can sitting on the counter with charred towels.
After sanding and re-finishing the benches at my parent's house the day before, we left the rags with linseed oil on them in a pile on top of the container. Overnight, the rags spontaneously caught fire and luckily burned out once they made contact with the metal can. My dad said if the can lid hadn't been sealed so tightly, the fire could have caused the entire container to explode, likely burning down the garage and neighbor's house in the process. Luckily, that wasn't meant to be a part of our story.
What I've learned:
Spontaneous combustion is combustion without a spark or a flame. I thought the oily rags needed contact with fire or at least the sun to burst into flames, but this is not the case. Linseed oil (and other materials) in a confined space can oxidize, build heat, and ignite.
How to avoid spontaneous combustion:
Soak rags and brushes that have come in to contact with flammable materials, such as coals and oils, in water. Let them dry flat on a concrete surface so the combustable solvents can evaporate. Throw away the rags in a metal trashcan with a lid that seals. I've also heard you can put chemically soiled rags in a plastic bag filled with water and then throw them away. Whatever you do, don't wad them up and leave them on top of a chemical container in your parents garage! Lesson learned.
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