To prevent stain or oil-based finish rags from spontaneously combusting, stop the heat from building up by laying the rags flat outside to dry completely. Alternatively, submerge them in water inside an airtight metal container. Never wad them up or throw them in a regular trash can.
Oil-based paints, stains, and varnishes are often used for home improvement projects. It is common to use rags to wipe up spills or clean brushes. But wet rags can ignite on their own. They can start a fire if not handled carefully.
Solvent-moistened or wet wiping cloths, rags, towels, drop cloths, steel wool, brushes, protective coverings and work clothes should be handled as follows: Immerse item(s) in water in a metal container and seal with an air tight lid.
Place in a sealed metal container: Even after drying, store them in a non-combustible, sealed container until disposal. Follow local disposal regulations: Rules vary by location, but many areas have household hazardous waste programs or drop-off locations specifically for paint, solvents, and oily rags.
Certain oils, like linseed and tung oil, oxidize rapidly and generate more heat, making them more likely to spontaneously combust within hours. Rags balled up in a confined space, especially in warm environments, trap heat and speed up the process.
Rags used with water-based products can either be cleaned or thrown out. Rags used with oil-based products, especially with any stain, are best to be thrown out and not washed. To do this safely, hang the rags to dry in a well ventilated area away from any sparks or flame.
If you 'wash' them with mineral spirits, you sure can. But you wind up using a lot of spirits this way - in the long run it might just be cheaper to buy painting rags in bulk.
Oil based stains usually do ok in cold weather. Your glue and most clear coats... not so much. I have a couple of projects that I'm pushing the envelope to get done before it gets too cold myself. Check the label.
They spontaneously combust due to the build up of heat (produced from the reaction of the oil drying) getting trapped in the folds and layers of the rags. They dont get hot enough to burst into flames in their own, so laying flat is perfectly safe. Spread them out to expose the most surface area to the air.
Avoid this type of fire by following a few simple and proven tips: Store piles of hay, compost, mulch, manure, and leaves away from buildings, in case a fire occurs, and keep the piles small to allow for the circulation of air and the dissipation of heat.
Rags soaked with oil-based paints, stains, linseed oils, varnishes, polyurethane, or paint thinners have the potential to spontaneously combust.
Prolonged exposure to these products without proper ventilation can also result in wood stain poisoning. This more serious level of exposure may result in a burning sensation, blurred vision, and collapse. In this case, seek medical attention immediately.
Oily rags can spontaneously combust and catch fire, thereby igniting a building or other property and causing significant fire damage. Oily rags that get folded or balled up, tossed on the floor or in the trash, can begin the process of oxidation.
Environmentally Responsible Disposal
Safe methods include laying rags flat to dry or placing them in sealed, water-filled metal containers. They should NEVER be tossed together in combustible containers, such as trash bags, plastic trash barrels or cardboard boxes.
Tung oil is highly durable and water-resistant, making it ideal for outdoor applications. It's also generally more expensive than linseed oil. Linseed oil protects wood but can be prone to scratches and is less water-resistant than tung oil, making it better suited for indoor wood products.
DA alone shouldn't leave much(if any) residue behind on your rags, so spontaneous combustion shouldn't be an issue. If you're worried about that though the best solution is to throw a rag in water so it can't build up heat to combust. As for disposal, it really depends on the other chemicals in the dirty alcohol.
Benefits of a waterbased stain include: Non-flammability, which makes the clean-up process easier. Because water is the solvent, used rags can be piled together, stored together, and disposed of in a regular garbage can without the risk of sparking a fire. Used rags will not spontaneously combust.
Once the rag is no longer in use, soak it in a bucket of water. Then, wring out the rag and allow it to dry flat, preferably outside. The key is to keep anything from smothering the rag as it dries since it releases heat as it dries.
My technique is:
Most stains can be applied from about 50° F to 90° F — but many people don't realize this range refers to the temperature of the wood surface, not the air.
Extreme hot and cold temperatures can damage finishes. Oil base finishes are not as vulnerable, but water borne products are extremely sensitive. So if you live in Wisconsin, don't leave your finishes in an unheated garage. Frozen topcoat looks like this.
Many food or beverage stains, such as chocolate, jam, baby food, beer, and dairy are more easily removed with cold water soaks and washes. Cold water is also recommended for urine and blood stains. Other stains, especially oily or greasy ones, do better in warm or hot water.