Safe Storage & Disposal of Oil-Soaked Paint Rags (provided by Gamblin Colors)
Oil paint and oil painting mediums “dry" when exposed to air. That is, they oxidize, or react with atmospheric oxygen to form a dry paint film. This chemical reaction is exothermic generating a small amount of heat through the drying process. When oxidation occurs in a pile of oil-soaked rags that air can still penetrate, the bulky fabric acts as thermal insulation, and the center of the pile can exceed the deflagration temperature causing a fire.
Many oil painters don’t use enough paint rags or paper towels in a studio session to be concerned about them building up. Simply hang up one or two used paint rags when done painting for the day allowing them to dry out. Once dry, paint rags can be reused or safely disposed of in household garbage. Individual paint rags, even saturated with oil and Gamsol, will not spontaneously combust when laid out or hung up alone to dry.
To dispose of oily rags not yet dry, place them in an airtight plastic bag, soak them with water, seal the bag securely and dispose of in an outdoor trashcan or dumpster. Oil and Gamsol soaked rags will not spontaneously combust after being soaked in water and sealed in a bag or other airtight container.
If you go through a large quantity of paint rags throughout the day, we recommend temporary storage in a Metal Oily Rag Can (e.g. JustRite) until they can be hung up to dry or prepared for disposal. In the event of spontaneous oily rag combustion, metal oily rag cans will contain the fire and prevent it from exceeding the smoldering stage. The tight-fitting and self-closing lid of an oily rag can is airtight so that if oxidation were to generate enough heat to ignite the oily rags inside, all oxygen would be quickly consumed and the fire would extinguish. The can prevents a smoldering fire from escaping beyond the lid as a hot gas or flame.
NOTE: Personally, I have 2 large galvanized trash cans with lids - one at the end of my studio where I work in Cold Wax/Oils and the other in the area where I work in encaustic. When I reached out to Gamblin Colors to review my safety video, they shared the above information with me and I decided to remove this section from my original video. However, I do have these special containers in my studio just to be safe!