How to dispose of polyurethane depends on whether it is water-based or oil-based. Water-based polyurethane is less hazardous and, in many areas, small amounts can be dried out and put in the trash once solid. Oil-based polyurethane contains flammable solvents and belongs at a household hazardous waste drop-off, or a paint take-back site where one exists. In both cases, never pour finish down a drain, and handle used rags carefully: rags soaked with oil-based finishes can heat up and catch fire on their own as they dry.
Check the label
The can will say “water-based,” “waterborne,” or “clean up with soap and water” for water-based finishes. Oil-based products say “clean up with mineral spirits” and list flammable warnings. Wipe-on poly and spar urethane are usually oil-based.
Water-based polyurethane
| Amount | What to do |
|---|---|
| A thin layer in the can | Leave lid off in a ventilated spot until hard |
| Up to about a quarter can | Mix with cat litter or a paint hardener until solid |
| Larger amounts | Paint take-back program or hazardous waste |
Once completely solid, many areas accept the can in the trash with the lid off so haulers can see it is dry. Rules vary, so check locally. See how to get rid of old paint.
Oil-based polyurethane
Take oil-based finish to household hazardous waste in its original, tightly closed container. Do not dry it out in large amounts, since solvent vapors are flammable and harmful. Some states have paint stewardship programs that accept stains, varnishes, and polyurethane at retail drop-off sites.
Oily rag safety
Rags, cloths, and steel wool used with oil-based polyurethane, stain, or oil finishes can spontaneously combust as the oils cure.
- Lay rags flat outdoors on a non-flammable surface to dry, away from buildings.
- Or put them in a metal can filled with water and a tight lid.
- Once fully dry and stiff, they can usually go in the trash.
- Never pile wet rags in a bucket, bag, or trash can.
Brushes and pads
Clean water-based finish from brushes with soap and water. For oil-based finish, clean brushes with mineral spirits, then let used spirits settle in a sealed jar; pour off the clear solvent for reuse and take the sludge to hazardous waste. See leftover solvent and paint thinner.
Aerosol polyurethane
Spray cans of polyurethane are pressurized and flammable. Use them up or take partly full cans to hazardous waste.
Storage
Store cans sealed, upright, and away from heat and freezing. Skinned-over finish in a can that has been opened many times is often past use; take it in rather than keeping it indefinitely. See how to dispose of wood stain.
How to dispose of polyurethane FAQ
Can I throw polyurethane in the trash?
Small amounts of dried, water-based finish may be allowed. Oil-based goes to hazardous waste.
How do I dispose of rags with polyurethane on them?
Dry them flat outdoors or store them in a sealed metal can filled with water.
Is polyurethane hazardous waste?
Oil-based polyurethane generally is; water-based is less hazardous.
Can I pour polyurethane down the drain?
No, for either type.
Do paint take-back programs accept polyurethane?
In many states with paint stewardship programs, yes.
The bottom line
How to dispose of polyurethane: harden small amounts of water-based finish and trash them where allowed, take oil-based and larger amounts to household hazardous waste or a paint take-back site, and dry oily rags flat or in water to prevent fires. Use the map to find a hazardous waste or paint drop-off near you.
Guides and tools
Old paint guide · Household hazardous waste guide · Dump cost calculator · All material guides