Floor finish fumes and stain rags: staying safe while hardwood is refinished
Updated · KeystoneProGuide editorial team
Are floor finish fumes harmful?
They can be, while they last. The U.S. Environmental Protection Agency (EPA) says paints, varnishes and wax all contain organic solvents, which release volatile organic compounds (VOCs) while they are used and, to some degree, while they are stored. It lists eye, nose and throat irritation, headaches, loss of coordination and nausea among the possible effects, and damage to the liver, kidneys and central nervous system for some compounds. It also says not much is known about the health effects of the levels usually found in homes. The practical message is to keep exposure short and air plentiful.
How much do levels rise during refinishing?
A great deal, for a while. The EPA says studies found several organic compounds averaging 2 to 5 times higher indoors than outdoors in ordinary homes, and that during and for several hours after activities such as paint stripping, levels may reach 1,000 times background outdoor levels. It adds that elevated concentrations can persist in the air long after the activity is over.
Formaldehyde is part of the picture too. The EPA lists lacquers and finishes among household products that can contain it, and says it can irritate the eyes, nose and throat.
Do different finishes make a difference?
The National Wood Flooring Association (NWFA), the hardwood trade's association, describes the main types. Surface finishes form a film: water-based finishes are normally clear and dry quickly, oil-based finishes are amber, moisture-cured finishes are more moisture-resistant than the others, and conversion varnishes are very durable. Penetrating finishes, such as natural oils and hard wax oils, soak into the wood. Some finishes are cured instantly with ultraviolet light, on site or at the factory.
The NWFA does not rank them by fumes, and no government source read for this guide does either. What the NWFA does point out is the alternative: a factory-finished floor arrives with its finish already applied and can be walked on immediately after installation, while a site-applied finish needs drying time during which nobody can walk on the floor. If fumes are a particular concern in your household, that trade-off is worth discussing before you choose.
How should you plan around a refinish?
- Ask for the product data before the job. Ask the refinisher which stain and finish it will use and to show you the labels, which set the ventilation and drying instructions.
- Plan to be out. The EPA's general advice is to use VOC-emitting products where there is plenty of fresh air, and, when a label calls for a well-ventilated area, to go outdoors or use exhaust fans or open windows. During sanding and finishing that is easier with the household elsewhere.
- Keep the air moving afterward. Since levels can stay up after work stops, ventilate for as long as the label and the contractor advise before moving back in.
- Keep it cool and dry where you can. The EPA says heat speeds the release of formaldehyde from products and that air conditioning and dehumidifiers that keep temperature moderate and humidity low can reduce it.
Sanding comes before any finish and carries its own warning. The Occupational Safety and Health Administration says wood dust that becomes airborne during sanding may cause respiratory symptoms and cancer, though the extent of these hazards has not been clearly established. Containment and dust collection are fair questions to put to any refinisher.
Why do stain rags catch fire?
Because some finishes generate heat as they cure. In April 2022 investigators in Ludlow, Massachusetts, found that a house fire had started with oil-based staining rags left overnight in a five-gallon plastic bucket. The town's fire chief said many people do not realize that the oils in some paints and stains release heat as they dry, and that rags left in a pile or a confined space like a bucket can build up enough heat to ignite. The state's fire service noted that, less than a month earlier, oil-soaked rags had caused a fire in a home without working smoke alarms that killed a teenager.
The fire chief's advice was to leave oil-soaked rags to dry individually outdoors, on the ground or on a metal rack, well away from anything that burns. The U.S. Fire Administration says to keep oily rags in airtight containers away from heat, and, in its advice on garages, to store oil, paints and varnishes in a shed away from the house.
What should a refinisher do with leftover products and rags?
Ask before the job starts: who takes the rags, applicator pads and leftover stain and finish away, and how. If anything is left behind, the EPA's advice for leftover chemicals is not to throw partly full containers in the trash, but to use local collection days for household hazardous waste, and to buy only what you will use.
What about strippers and adhesive removers?
Treat them with particular care. The EPA says some paint strippers and adhesive removers contain methylene chloride, which is known to cause cancer in animals and which the body converts to carbon monoxide. It advises reading the label's health warnings and using such products outdoors where possible, or indoors only with good ventilation. Ask whether any stripper or adhesive remover will be used, and which one.
How a refinish runs from start to finish is in what happens when hardwood is refinished, the homeowner's safe role is in installing or refinishing floors yourself, and emissions from new laminate, vinyl and carpet are in new flooring and indoor air. Businesses are listed on the flooring contractors directory page.
Sources
- Volatile Organic Compounds' Impact on Indoor Air Quality, U.S. Environmental Protection Agency
- Facts About Formaldehyde, U.S. Environmental Protection Agency
- Finishes, National Wood Flooring Association (NWFA)
- Ludlow Fire Started with Oily Rags, Massachusetts Department of Fire Services
- Basement and Garage Fire Safety, U.S. Fire Administration
- Wood Dust - Overview, U.S. Occupational Safety and Health Administration
- Protect Against Exposures to Formaldehyde, U.S. Environmental Protection Agency