Mineral Spirits Before Polyurethane (How to Apply!)

Polyurethane is a protective wood finish favored by many DIY’ers since it is durable and easy to apply. But it’s vital to prep the wood first by cleaning it off so that the finish is as smooth as possible. What’s the best solvent to use for that?

You can use mineral spirits as a cheaper, more effective to clean wood for a smooth finish with polyurethane. Mineral spirits also only take 15–20 minutes to dry, so you won’t have to wait long before applying your polyurethane coat.

Here, we will discuss the benefits of using spirits before polyurethane and how to go about it.

Benefits of Using Mineral Spirits Before Polyurethane

Polyurethane is a finish that effectively protects wood. You do not necessarily have to use mineral spirits before polyurethane. However, the benefits that come from doing so are worth considering. Here is a closer look at what you get when using spirits before polyurethane:

· Remove Dust Particles

The main objective of using mineral spirits before polyurethane is to remove any dust particles that are still present after sanding. Failing to do this can result in dust particles and other contaminants affecting the quality of the next polyurethane layer.

· Spot and Correct Imperfections

Wiping wood down with mineral spirits allows you to inspect your DIY project properly to spot and correct faults before applying spirits. A polyurethane layer will also make faults noticeable, but at that point, you’d have to strip the coating off. The simple step of using spirits before polyurethane takes very little time and effort compared to having to strip a layer of polyurethane off and starting all over again.

· Effectiveness for a Small Price

Using a solvent like spirits for the benefits outlined here will not stretch your budget much. Mineral spirits are considerably cheaper than other alternatives and can also be used for other DIY purposes such as thinning your polyurethane, as thinner coats provide more control over the paint job.

Applying Mineral Spirits Before Polyurethane

Applying spirits on wood after sanding and before polyurethane helps eliminate loose dirt and resin. This is not always necessary with smaller wood pieces, but doing so will improve the chances of the next polyurethane layer being as perfect as possible.

If you are new to using spirits prior to applying a coat of polyurethane, here are the steps you should follow:

1. Sanding is the very reason you will use mineral spirits before polyurethane. Sand the wood until you obtain the smoothness you are looking for. The smoothness of your wood will determine how well your polyurethane adheres to it, but before you get to that point, you have to get rid of all the dust from sanding.

2.     Open your mineral spirits and dry cloth or soak a rag with mineral spirits. Use the soaked rag to wipe away dust particles so that the wood is immaculate and ready for a layer of polyurethane. You might want to repeat this step to ensure that you have gotten all the dust off.

3.     Before you go on to apply a layer of polyurethane, you should wait for any mineral spirits residue to evaporate from the entire surface. Mineral spirits will generally evaporate in 15 to 20 minutes when applied to a smooth surface.

4.     Apply a layer of oil-based polyurethane. When applying several coats of polyurethane, you may or may not have to sand between those coats. Follow the instructions on the polyurethane container about how long to let the finish dry. If you sand the wood before the following layer of polyurethane, use spirits again to remove all the dust.

Both spirits and polyurethane can be toxic. Employ safety precautions such as wearing rubber gloves and work in a well-ventilated area when using these chemicals.

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Mineral Spirits Between Coats of Polyurethane

While water-based polyurethane has to be applied five times or more for the best finish, you only generally need two coats of oil-based polyurethane finish. This is because oil-based polyurethane application produces thicker layers.

However, you can use more coats of polyurethane if you are finishing floors or furniture that you will use a lot. This will make them more resistant to damage.

coats of polyurethane

You do not necessarily need to sand wood between coats of polyurethane if you apply them within the recommended time frame. Some DIY’ers do so anyway to ensure a better bond between coats. If you go beyond the recommended time frame, you should sand the wood.

Using spirits between coats of finish will ensure that you get rid of all the dust and other contaminants before putting on another coat of polyurethane.

What If I Don’t Use Mineral Spirits Before Polyurethane?

Sanding before applying a perfect finish coat like polyurethane will make your wood smooth, repair certain imperfections, and bring out the wood’s natural beauty. But what happens if you do not use mineral spirits after sanding and before polyurethane?

Failing to use mineral spirits to wipe wood down before polyurethane will almost certainly leave sand residue behind. Those tiny particles of sand will negatively affect your results.

Even worse, the results might be so bad that you end up having to strip off the layer of polyurethane. This would take time and effort and drive up your overall costs.

Using spirits after sanding is a small part of this process that you should not skip.

Can You Use Mineral Spirits with Water-Based Polyurethane?

Mineral spirits are a solvent derived from petroleum. As such, spirits are not meant to be used with water-based polyurethane. You have to choose an oil-based polyurethane if you want to use mineral spirits with it.

Before starting your DIY project, you have to make sure that you are using a suitable polyurethane. You will find this wood finish in oil-based and water-based versions. You want to choose an oil-based polyurethane because mineral spirits simply will not work with water-based products. 

Conclusion

You can use polyurethane to protect wood and make it look as beautiful as possible. Wiping the wood down before applying a polyurethane coat makes bothersome dust particles disappear and ensures excellent results.

No matter how many polyurethane coats you plan on applying, mineral spirits will make your DIY project a lot better.