Before you deserve to decide even if it is water based polyurethane or oil based polyurethane is ideal for your project, you require to define what you want the end result to look like and also how you want it come perform.

You are watching: Can you put oil based polyurethane over water based polyurethane

Let’s start with why girlfriend would use polyurethane in the an initial place vs. Other species of lumber finishes such together shellac, lacquer, varnish, etc.

Based on my 30+ years using and also formulating hardwood finishes, it is finest to use a urethane when your main objective is maximum chemical resistance and also film hardness, i.e., durability. That no accident hardwood floors, for example, are usually finished through urethanes.

With that in mind, right here is a head-to-head comparison of exactly how water based polyurethane and oil-based polyurethane ridge up.

There can certainly be exceptions (some of i m sorry are provided below) yet the below overview need to make her decision easy 90% that the time…

Final complete Look and Feel

A well-engineered, water based polyurethane will be equal in clarity to oil-based polyurethane. The main distinction is commonly color: water based polyurethanes are totally clear and (again, if fine engineered) will certainly not yellow end time. This is ideal if you want the natural shade of your timber to continue to be constant. Some civilization prefer the warm, “amber” hue the oil-modified polyurethane imparts come wood, but keep in mind, this “yellowing” will certainly continue and intensify over time. In regards to “feel,” due to the fact that it’s thicker, one coat of oil-based poly would most likely feel softer 보다 water based poly (but hardly ever is just one coat of water based poly used). Likewise, some human being find oil based poly dents and peels easier, whereas water based poly might scratch easier. Store in mind the there space variations to every urethane type, so check out the product spec sheet carefully.

Winner: Tie (+1 come each)

Durability

Oil based polyurethane had actually the edge here for a while, but water based polyurethane (especially the self-crosslinking variety) has captured up – it’s now equal to solvent based products concerning scuff, mar, UV, water, and corrosion resistance. If you’re trying to do something practically bombproof, oil based may be the method to go, yet the hazardous additives and also flammable solvents you will do need method you would almost be making a bomb.

Winner: Tie (+1 come each)

 

Safety

Oil based poly is do with highly flammable and also toxic solvents to enable the urethane resin come level and type into a cured film. The clean-up process, too, calls for exposure to high-odor hydrocarbon solvents now well documented to reason short- and long-term wellness problems. A well-engineered water based poly generally contains little or no ingredients considered “hazardous chemicals” as defined by OSHA. Likewise, a great water based poly will certainly have considerably lower (up come 50% lower) volatile organic compounds or VOCs.

Winner: Water Based Polyurethane (+1)

*

Drying and Re-Coat Time

All things being equal (temperature, humidity, etc.) oil based polyurethane will certainly take about two to three times much longer to dry between coats contrasted to faster-drying water based polyurethane.

Winner: Water Based Polyurethane (+1)

Number the Coats Needed

The water in water based polyurethane has tendency to “react v the grain” more, for this reason you regularly need to apply an ext coats to achieve a smooth, finish. A great rule that thumb: for every coat of oil based polyurethane, you may need to use at the very least two coats that water based polyurethane.

Winner: Oil Based Polyurethane (+1)

Number of Coats Available

With a water based poly, girlfriend have limitless coats available. Desire to put on six layers? walk for it. Oil based polyurethane, on the other hand, is susceptible to “sheeting,” scratching or chipping after ~ the first pair layers.

Winner: Water Based Polyurethane (+1)

Compatible Substrates and Adhesion

Water based polyurethane is exceptionally versatile; it will certainly bond to virtually anything including wood, (non-ferrous) metal, fiberglass, stone, cement and also carbon fiber. Oil based polyurethane adheres fine to almost everything, too…except itself. That method you should sand it between coats to create a mechanically bond to the next layer.

Winner: Water Based Polyurethane (+1)

Cost

The raw products used to do water based polyurethane cost more than the of oil based polyurethane, therefore the last price you pay is generally higher, too.

Winner: Oil Based Polyurethane (+1)

Application & Equipment

You can uncover both varieties of polyurethane in brush- and spray-friendly versions, for this reason “ease the application” is a tie. However, the short solvents in water based polyurethane provides it a longer “pot life” (the amount of time you can work with it before it becomes unusable) and it is much easier on her equipment.

Winner: Water Based Polyurethane (+1)

If we add everything up, this is the scoreboard:

Water Based Polyurethane (+7)

Oil Based Polyurethane (+4)

Depending on the prestige or “weight” you place on the categories above, her scoreboard might come out looking differently.

For example, for me, safety and security to the lumber finisher and also the environment is worth at the very least +5 points, in which situation water based polyurethane wins through an even larger margin.

See more: Night At The Museum Teddy Roosevelt, Theodore Roosevelt (Night At The Museum)

What carry out you think? do you have experience using (or inquiries about) water based poly vs. Oil based poly?

Please share her thoughts or review what others are saying in the comments section below.