How to dispose of oily rags safely

Why do oily rags catch fire?

Some oils harden by soaking up oxygen from the air. That reaction gives off heat. NFPA, the national fire safety group, explains that a pile of rags traps the heat. It keeps building until the rags catch fire, with no spark or flame needed.

The fire can start after you’ve cleaned up and walked away. NFPA says an average of 900 home fires a year start when oily rags catch fire or are ignited.

Rags wet with thinner or gasoline are a fire risk too. NFPA notes that vapors from these liquids can catch fire from a spark or flame. Handle them the same careful way.

Which rags are dangerous?

Step by step: how to make oily rags safe

1. Don’t wad or pile rags while you work. Keep a metal can with a lid nearby.
2. When you’re done for the day, pick one of two methods: dry them, or dunk them.
3. To dry: take the rags outside. Hang them or spread them flat on the ground, one layer only. Weigh them down so they don’t blow away. Keep them away from your house, garage, deck and anything that can burn.
4. To dunk: put the rags in a metal container, cover them with water, and close the lid tight. Minwax’s safety sheet says to do this right away. NFPA’s tip sheet (which has you dry rags first, then store them this way) says to add detergent to the water to help break down the oils.
5. Store the closed can in a cool place, out of the sun and away from furnaces, water heaters and other heat.
6. Get rid of them the way your town says. Some hazardous waste sites take oily rags in a sealed can. Ask yours how to bring them in.

Where do you take oily rags?

Rules vary by town, so check yours. Here’s how one county handles it.

Hennepin County, Minnesota, takes rags soaked with gas, oil-based paint, oil, solvent and other flammable liquids at its two drop-off sites at no charge. It tells you to put them in a small, airtight metal container with a tight lid, and not to put them in the garbage.

Fire departments like Seattle’s say to check with your town about disposal. Minwax’s safety sheet for its oil-based stain says to dispose of soaked waste according to local fire rules.

PaintCare paint drop-off sites take paint, not rags or cleanup waste. Bring rags to a household hazardous waste site or event instead.

Can you wash oily rags?

Be careful. The National Park Service reported seven cases of oily rags or towels heating up and catching fire on their own over two years, in park kitchens and buildings under renovation. In some cases, towels smoked or caught fire after they were washed and dried. One crate of oil-soaked rags read 300 to 400°F on a thermal camera, then burst into flames when a firefighter carried it outside.

The Park Service says normal washers, dryers and detergents can’t fully remove oil from rags. So don’t count on a home washer and dryer to make oil-soaked rags safe. If you spill an oil finish on your clothes, NFPA says to take them off, let them dry outside, and wash them once dry.

What about shops and job sites?

For workshops, contractors and refinishers, the Park Service suggests UL-certified metal oily waste cans with self-closing lids, kept away from heat. Large amounts of rags from a business usually can’t go to a household site. Ask your county about small business hazardous waste programs or use a licensed hauler.

Do product labels warn about this?

Many do. Minwax’s oil-based stain safety sheet says that rags, steel wool, other soaked waste and sanding residue may catch fire if thrown away wrong. It tells you to put them right away in a sealed, water-filled metal container.

By 1994, Connecticut had passed a law requiring warning labels on drying oil products, such as furniture polishes with linseed or tung oil, according to a 1994 CPSC meeting record. The paint industry’s voluntary labeling guide covers the same hazard. If your can has this warning, take it seriously.