Differences Between Oil-Based And Water-Based Polyurethane

Polyurethane, a plastic-based resin, can be used in many different ways. When used as paint or varnish, it can provide a hard, durable gloss that is resistant to water and different kinds of chemicals. It is also very easy to apply. When clear, this type of resin is mostly used for woodwork and furniture. It basically has two kinds: water based vs. oil based polyurethane. Polyurethane paints and varnishes used to only be oil-based. However, it has been discovered in recent years that water-based polyurethane works just as well.

Oil-Based Polyurethane

Oil-based polyurethane has a more distinct odor and takes a longer time to dry than water-based ones. Another downside of oil-based polyurethane is that if you decide to use brushes, you will have to take time to clean them with a thinner. On the other hand, oil-based polyurethane lasts longer and is also more durable than water-based ones. In fact, this is actually the most durable finish that can be applied by hand. It is also easier to apply than water-based polyurethane and is one of the best options to use if you want your furniture to have a natural look. Oil-based polyurethane also tends to penetrate the surface of the wood, thus, wetting its cells and giving it a darker color. This penetration can also make the surface of your furniture shinier.

One good method of applying oil-based polyurethane is to use mineral spirits to thin the finish before wiping it on. This will prevent your furniture from having a plastic look. Also make sure that not to over-brush or over-wipe so that brush marks can be prevented and so the finish will be smooth and level. When used on furniture, make sure that it is completely dry before touching or moving it. Usually, you have to wait four to five hours before applying new coats and twelve hours after applying the last coat before you can actually use your furniture. Oil-based polyurethane only requires around two to three coats since it contains 45 to 50 percent of the solids that create the protective finish.

Water-Based Polyurethane

Water-based polyurethane has all the benefits of the oil-based ones, but it dries a lot faster and the odor is not as distinct. It also has a clear finish that has a lasting effect, although most of the time it is shorter than oil-based ones. The addition of urethane to water-based finishes makes it tougher and more resistant to scratches. The tools used to apply this kind of finish can also easily be cleaned by water instead of applying thinner. Furthermore, it releases fewer harmful chemicals and their containers can be disposed of in regular trashcans instead of special ones for hazardous wastes. This makes it both safer for the environment and your health. Because of this, water-based polyurethane can also be used around children. However, it is not as heat resistant as oil-based polyurethane. It is also harder to apply because it tends to run.  Apart from that, it doesn’t become glossy and it also has a tendency to show brush marks. Some water-based finishes can also be damaged when exposed to water for long periods of time. It also has a tendency to stay on the furniture’s surface instead of penetrating it so it actually makes the wood’s color lighter. In addition to that, it is also prone to watermarks and may also raise the wood’s grains. Water-based polyurethane is also more expensive than oil-based ones, usually costing twice as much.

Because most water-based polyurethane only contains 30 to 35 percent solids, the recommended number of coats for a nice finish is four. Application of additional coats may also be required every two years. Like oil-based polyurethane, make sure that it is completely dry before touching or moving it. However, unlike the oil-based ones, the waiting time between coats is usually only about two hours.

Both oil-based and water-based polyurethane are the most effective finishes that you can use if you want your furniture to have good protection and if you want to make their wood tougher. However, they also dry slower than other finishes so overspray’s may be required. This also means that dust and other air particles are more prone to stick to it. Water based vs. oil-based polyurethane can both be applied by brushes and spray-on cans. When using cans, make sure that you don’t shake them since this will produce bubbles that can appear in the finish. In both cases, it is better to apply thinner coats when working with vertical areas so that there are minimal drips or runs. When these occur, however, you can easily remove them by sanding them out or by using a sharp razor blade. When working with either of these types of polyurethane make sure that you stay in an area that is clean and well ventilated.

Choosing The Correct Finish

It is very hard to choose from water-based vs. oil-based polyurethane, especially if you are not used to working with wood. In choosing between the two, it is important to remember not only to look at the pros and cons of each but also at external factors that may affect them. These factors may include your experience level, the temperature and other weather conditions in your work area, and even the amount of dust in it.

In the battle between water-based vs. oil-based polyurethane, there is no real winner. This is because both have their own advantages and disadvantages, and the right finish to use actually depends on many factors. What is important is that you know how to use each one correctly and that you use them according to their strengths.

3 thoughts on “Differences Between Oil-Based And Water-Based Polyurethane

  1. Water based Polyurethane varnish dries too fast if one uses it for large areas, color patches will ALWAYS form between wet and dry brush or roller re-charges and the finished effect will always be poor visually. The old method of feathering brush stokes together with varnish, linseed oil and transparent paints does not apply here. So beware how you use it; sanding rubbing down seems like a huge amount of work for a simple finish?

    1. No, oil based top coats don’t work over water based varnishes. The reason being that the oil products are designed to penetrate into wood fibers while water finishes sit on top. The oil varnish will sit as a layer and not properly bond. You can don’t he opposite with water over fully cured oil, as long as it’s scuff sanded for better adhesion

Comments are closed.