Oil-based and water-based polyurethanes are two versions of the same type of protective finish. Whether refurbishing stair railings or finishing floors, trim, or doors, learn the differences between water-based and oil-based polyurethanes and which one to choose.
Polyurethane Finish
Polyurethane is a clear, thin liquid coating that protects wood and enhances the wood grain. It is similar to varnish, shellac, and lacquer, except that polyurethane is polymer-based.
Water-based vs. Oil-based Polyurethane: Major Differences
Water-based Polyurethane
Pros
Odorless
Water clean-up
Flexible finish
Cons
More coats needed
Less durable
Touch-ups necessary
Water-based polyurethane uses water, rather than solvents, as the base for carrying the polyurethane solids.
Like oil-based polyurethane, water-based polyurethane can form a hard protective film, but more coats are required to achieve that level of protection.
Oil-Based Polyurethane
Pros
Hard shell
High build
Fewer coats needed
Cons
Long curing time
Sharp odor
Difficult clean-up
Oil-based polyurethane uses various petroleum and mineral solvents as the vehicle for the polyurethane solids.
Oil-based polyurethane is self-leveling, which means that it will become smooth when applied to a horizontal surface.Oil-based polyurethane cures to form a tough shell, so it's a good choice for applications where durability is a concern.
| Water-Based | Oil-Based | |
| Characteristic | Flexible but hard | Extremely hard |
| Number of coats | Four to eight | Two |
| Clean up | Water and soap | Mineral spirits or paint thinner |
| Dry time | 1 hour | 2 to 3 hours |
| Recoat time | 3 hours | 8 to 12 hours |
Appearance
Water-based polyurethane begins milky-white in the can but dries clear. Very little, if any, color is imparted by the water-based polyurethane. One or two coats apply nearly invisible and with almost no build. It's not unusual to use four to eight coats of water-based polyurethane.
Oil-based polyurethane coatings achieve a rich, golden glow in few coats. Oil-based polyurethane, available both in spray and brush-on formats, creates a hard protective shell in fewer coatings than with water-based polyurethane. It does leave a slightly yellow sheen, especially with multiple coatings, though this may be desired in some applications.
Durability and Maintenance
Water-based polyurethane tends to be less durable than oil-based products. Water-based polyurethane scratches and dents easily.
Oil-based polyurethane coatings provide excellent abrasion and scratch resistance.
Application
Water-based polyurethane can be applied with a brush, roller, spray, or rag. The smell is not noxious, though it's always a good idea to ventilate the room. Because water-based polyurethane is so thin, it can be challenging to see where you have applied the product.
Oil-based polyurethane can be applied with a brush, roller, spray, or rag. During application, the odor is sharp and pronounced, and many people find it objectionable. By the time the product has fully cured, the odor will have gone away.
Tip
Applying polyurethane by spraying it is the best way to ensure even, professional-looking results.
Drying and Recoat Time
Water-based polyurethane dries and cures fast. This allows for faster application of multiple coats compared to oil-based polyurethane.
Oil-based polyurethane dries and cures slowly. One coat dries to the touch in two to three hours. Recoat time for oil-based polyurethane can be up to 12 hours.
Clean-Up
Water-based polyurethane coatings require only soap and water to clean off hands or tools.
Oil-based polyurethane requires mineral spirits or paint thinner for cleanup.
How to Choose
Water-based and oil-based polyurethanes are not mutually exclusive. Wherever you use water-based polyurethane, you can also use oil-based polyurethane.
Water-based Polyurethane
Water-based polyurethane is easy to apply and clean up after. Water-based polyurethane should be your choice if you are averse to dealing with messy, odorous solvents. Typical uses for water-based polyurethane include:
- Finishing doors
- Revitalizing chairs
- Protecting furniture
- Finishing stained window trim
Oil-based Polyurethane
Use oil-based polyurethane for a hard shell look without the numerous coats required with water-based polyurethane. Typical uses for oil-based polyurethane include:
- Sealing a butcher block countertop
- Refurbishing cabinets
- Finishing stair railings
- Finishing wood floors
FAQ
Is it necessary to sand between coats of polyurethane?
You should sand between coats of polyurethane. Sanding between coats of polyurethane ensures a smoother finish. Be sure to wait the full recoat time before reapplying the polyurethane finish.
How many coats of polyurethane do I need to apply?
With oil-based polyurethane, you should apply one or two coats. With water-based polyurethane, you may need to apply as many as four to eight coats.
Should I wear a mask when applying polyurethane?
Wear a NIOSH-approved P-95 respirator mask when applying oil-based polyurethane. The area should also be well-ventilated. A respirator mask is usually not necessary when applying water-based polyurethane.
How Much Does It Cost to Refinish Hardwood Floors?
