How to Tell If Polyurethane is Oil or Water Based

Polyurethane is a protective liquid coating used for furniture or woodwork to prepare the area before painting. There are two types of polyurethane, oil-based and water-based polyurethane.

You can find the differences between these two to decide which one is best for you.

What Does Water-Based Polyurethane Look Like?

Water-based polyurethane is clear, and unlike oil-based polyurethane, it doesn’t turn yellow over time if you choose the well-engineered one. Since this is clear, it allows your wood’s natural color to remain there after application.

Using water as the base, water-based polyurethane requires less time to dry compared to oil-based polyurethane. It dries faster, so you can apply another layer of polyurethane in less time.

Because of its clear texture, even after some application layers, it doesn’t look as thick as oil-based polyurethane.

However, if you need a hard shell, you must repeat the application several times. Sometimes it is hard to recognize which part has been applied with polyurethane due to its clear color.

This is also why water-based polyurethane is more prone to scratch.

Can I Put Water-Based Polyurethane Over Oil-Based Polyurethane?

Is it okay to use both types of polyurethane? Sure it is. Whether putting water-based polyurethane over oil-based polyurethane or vice versa, you can always do it to refinish your furniture or start a new project.

Some people like applying oil-based polyurethane first to bring out the charm of the wood surface and finish it with a clear coat of water-based polyurethane.

It won’t ruin the finish. Because water and oil can’t be mixed doesn’t mean they don’t match each other. You just need to consider some things to get the best result.

If you refinish an old piece of furniture with oil-based polyurethane already applied, you can just top it with water-based polyurethane.

However, if you start a whole new project, you must wait until the oil-based polyurethane dries completely for about two weeks up to two months, depending on what brand of oil-based polyurethane you are using.

Making sure that each polyurethane is dried is very important because water and oil won’t mix when wet. Let each coat dry if you want them to complete each other.

What is the Main Disadvantage of Using Water-Based Polyurethane?

While there are many good things about water-based polyurethane, it has some disadvantages. This type of polyurethane is safer than the oil-based type since it doesn’t contain VOC or Volatile Organic Compounds.

However, water-based polyurethane is less durable without this compound than the oil-based type.

Also, since it is clear in texture, it should be applied around 4 to 5 layers to give it a good appearance, while oil-based polyurethane doesn’t need that many layers since it is thick.

Is Water-Based Polyurethane Shiny?

Since it has water as its base, water-based polyurethane is not shiny. It has a clear finish that you can still expose the grain and the natural color of your wood surface.

Even after the second or third application, it still provides a clear appearance. Unlike oil-based polyurethane, its warm glow can enhance the wood’s character and improve its look.

Water Based vs. Oil Based Polyurethane Durability

As mentioned above, oil-based polyurethane is more durable than water-based polyurethane. It can last up to 10 years, with its thick coat protecting your wood surface.

Its thickness makes it withstand scratches, so your wood surface will look smooth for a long time.

Oil-based polyurethane will darken the tone of the wood surface over time, making it look stronger, while water-based polyurethane just stays the same, sometimes leading to a duller look.

So, the beauty of oil-based polyurethane lasts longer.

Water-based polyurethane usually lasts only five years, with some areas peeling off over time, so you need to refinish the job, which will cost more.

Water Based vs. Oil Based Polyurethane for Furniture

So which one should you go with for your furniture? Water-based or oil-based polyurethane? It depends on what wood surface to apply and what finish you want.

Oil-based polyurethane is thick. It requires more time to dry, but it protects well since it withstands scratches. Sometimes, you just need a single coat because it is so thick.

It is best used on wood surfaces or furniture that requires high durability, such as hardwood flooring, cabinets, countertops, and railings. Its hard shell and golden coating are great protection when used in these areas.

Water-based polyurethane is more suitable for those who want to work with less odor and less smell since this type has almost no odor and is easy to clean up.

You can clean your wood surface after application with just water and soap.

Also, water-based polyurethane is more flexible to any look because of its clear finish. You won’t see any thick layer with one or two coats, just like when applying oil-based polyurethane.

How to Apply Water-Based Polyurethane

No matter what type of polyurethane you use, preparing the wood area is important because polyurethane works best on smooth surfaces.

So always sand your wood surface with 220-grit sandpaper at least, and if your wood surface is the open grain types like walnut, oak, and ash, don’t forget to add a grain filler.

Everything should be perfectly smooth before the application.

For water-based polyurethane, if you apply it on a piece of wood surface with the stain, you have to rough it up with synthetic steel wool. This method helps the water-based polyurethane apply nicely over oil stains.

Using a cloth, foam pad, or brush, start with a very thin coat and let each coat completely dry. You can have three coats for a light finish or four for more protection. More coats of each purpose will be better.

How to Apply Oil-Based Polyurethane

Applying oil-based polyurethane has the same preparation, but it takes more time to finish. Applying oil-based polyurethane is best with a fine bristled brush in straight strokes.

This technique will help to remove as many bubbles as possible.

Each coat of polyurethane should be sufficient, not too thick nor too thin. The time for each coat to dry is longer than the water-based type. Once dry, the polyurethane should be lightly sanded with 320-grit sandpaper.