Oil finishes and the rag warning
Linseed, tung, and Danish oil are label names. The rag warning comes first.
Disclosure: We may earn a commission if you buy through links on this page. It does not change our guidance. Affiliate Disclosure
Rags first
Massachusetts' Department of Fire Services says: "The oils in some paints, stains, and varnishes release heat as they dry. If oily rags and applicators are left in a pile, a box, or the trash, the heat can remain trapped and cause a fire that quickly spreads to nearby combustibles." Follow the label and your local fire officials.
What the National Park Service describes
The National Park Service describes a fire crew that applied linseed oil to tool handles with a rag. NPS says that even though the crew placed the rag "outside to dry flat on a workbench," it "caught fire, started the workbench on fire, and spread up the wall of an attached shed." For a project at home, NPS says to "spread the soiled rags in a single layer on concrete to prevent the buildup of heat."
Label names
Linseed oil, tung oil, and Danish oil are names makers use on their labels. The label says what is in the product and how to use it. Words such as food safe or non-toxic on a label are the maker's terms, not ours.
Ventilation
EPA says to "Increase ventilation when using products that emit VOCs" and to "Meet or exceed any label precautions."
This is general information, not legal or safety advice.
Sources: Massachusetts Department of Fire Services (mass.gov), Disposing of oily rags; National Park Service, Fire Prevention 52: Spontaneous Combustion, Fact or Fiction?; Colorado Department of Public Health and Environment, Preparing products found in your garage for disposal; EPA, Volatile Organic Compounds' Impact on Indoor Air Quality.
FAQ
General information only. Follow every product label and increase ventilation when you finish, as EPA advises. State fire and health agencies warn that rags used with some oil-based stains and finishes can catch fire on their own: never leave them in a pile, and dry and dispose of them as the label and your local fire officials direct. CPSC says to anchor furniture with drawers, doors, and shelves to the wall. In an emergency, call 911.
Next: oily rags
Never leave them in a pile.
