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Do I Sand the Final Coat of Polyurethane? (Explained)

Polyurethane is a protective coating used over paint. It prevents the paint from fading and getting damaged due to external factors.

That being said, after applying this protective finish, you might be wondering if you need to sand the surface. You might also want to know how you can make the surface smooth. Let’s find the answers to all your queries about sanding the final coat of polyurethane.

Do I sand the final coat of polyurethane?

You do not necessarily have to sand the final coat of polyurethane. You can however do it if the final finish did not meet your expectation. By sanding the final finish of polyurethane, you make it smoother and shinier. You should only sand the final coating after the paint becomes completely dry.

You can sand the final coat of polyurethane if you want to make it more polished and smooth. The final finishing of the polyurethane usually has dust nibs, streaks, and bubbles, which can make the whole surface rough. You can get rid of the rough surface by sanding it.

Polyurethane is most commonly seen in the form of flexible and protective foam. It is one of the most common materials used in home furnishings such as chairs, beds, tables, and other furniture.

The polyurethane foam serves as a cushioning material for upholstered furniture, making it more durable, and smooth. It can also prevent the paint of the furniture from fading. In fact, by coating old furniture with this finish, you can bring back the shine.

Although the polyurethane finish forms a coating above the paint, the surface can still have bubbles and rough patches on it. By sanding the final coat of the polyurethane, you can get rid of any bubbles and non-uniform patches from the polyurethanes’ final finish.

After the last coat of polyurethane, if you detect that the surface of the furniture is smooth enough for comfortably using them, you should sand it. After sanding the final coat of polyurethane, make sure to let it dry for at least a day.

You can use 240-grit sandpaper for sanding the final surface of this protective finish. However, you shouldn’t use sandpaper with a higher grit than 600, because if you do so the final coat may appear hazy and scuffed.

Should I wet sand final coat of polyurethane?

You should wet sand the final coat of polyurethane, it is even better than dry sanding. This is due to the fact that, by doing wet sanding, you won’t end up leaving any scuff marks on the final coat of polyurethane.

The wet sanding requires more than just sandpaper to complete the process. It requires sandpaper and mineral spirits or water for sanding.

Although this process has less probability of leaving scratch marks on the final coat, you will still have to complete wet sanding with utmost precaution. Once you do that, you will have a shinier and smoother surface than ever.

Do I have to sand between coats of polyurethane?

Yes, you should sand between coats of polyurethane if you want a smoother and better finish. Dust and dirt particles stick between coats of polyurethane when it is still wet. You can get rid of those minute particles by sanding between the coats.

By getting rid of the fine particles of dust between coats of polyurethane, you can enhance the adhesion of the inner coat. You can also help abrade the furniture surface by doing it. You should sand using 220 grit sandpaper to get the best outcome.

What do you use to sand polyurethane?

You will have to use sandpaper, sanding block, vacuum cleaner, tack cloth, and a respirator to sand polyurethane. In addition to that, for wet sanding, you will need mineral spirits or water, and a sanding sponge.

To sand polyurethane, you can use sandpapers of multiple grits. The recommended grits for sandpapers are 200, 400, and 600. However, you shouldn’t use a grit above 600 as it can make wet sanding intensely difficult and unsuccessful.

How long should polyurethane dry before sanding?

You should let polyurethane dry for 24 to 48 hours before starting the sanding process. You should sand the polyurethane only after the final coat hardens.

Sanding polyurethane only after it completely cures is also important for making the process successful. This is because particles of dust will get collected into the wet coat of polyurethane, which you will eventually remove by sanding.

How to sand polyurethane final coat?

Sanding the polyurethane final coat is not as complicated as it may seem to you at first. By getting the right tools and following the steps properly, you can effortlessly complete this process.

Let’s take a look in detail at how you can sand the final coat of polyurethane.

Vacuum the final coat:

After applying polyurethane on furniture, it will remain wet for a day or two. During that period of time, dirt and dust can accumulate on the surface.

By using a vacuum cleaner you can get rid of all the minute particles from all the corners of the coated surface. You can also use a microfiber cloth to clean the surface.

Wipe the surface:

Even after vacuum cleaning the surface on which you have applied the polyurethane coat, some dust particles may still remain in it. To get rid of the remaining dust particles, you should wipe the surface.

For water-based polyurethane, soak a lint-free cloth in water and then wipe the wall. In the case of oil-based polyurethane, soak a cloth in mineral spirits, then wipe the surface.

Let the surface dry:

Let the liquid that you have used to wipe off the dust evaporate. The surface will dry off quite fast if you don’t use too much liquid. After the surface gets dry, check if there are any particles of dust remaining and get rid of them if necessary.

Sand the final coat:

Now that your surface is ready, you should start sanding. Place the sandpaper on top of a sanding block and carefully swipe in the final coating. To avoid tampering with the smooth sections of the surface, do it slowly and carefully.

Clean the surface:

After sanding the final coat of polyurethane, you should clean it and check if there are any dents, bubbles, or dust nibs left on the surface. You can use a tack cloth to clean the surface.

How do you smooth the final coat of polyurethane?

The final coat of polyurethane gets rough due to dust particles in the air and the formation of bubbles in the final coat. You can make the final coat of polyurethane smooth with minimum effort and time.

Have a look at how you can smooth the final coat of polyurethane:


Sanding is a great way to make the final coat of polyurethane smooth. By sanding you can remove the bubbles and dust particles that make the surface uneven and rough.

The sanding process is also quite simple and easy. You can do it within a short period of time with minimal effort.

Use a roller:

A roller will help you apply the polyurethane coat very evenly. As a result, there won’t be any part in the surface where this protective finish will be more in amount than other areas. Needless to say, you can prevent the surface from being uneven by simply using a roller instead of a brush while applying the finish.

Apply it in a dust-free area:

The main reason for the polyurethane final coat becoming rough is dust particles that remain in the air. By applying polyurethane in an area that has a very little amount of dust in it, you can stop the final coat from becoming rough at the beginning.

Final Thoughts

You can sand the polyurethane final coat for a smoother finish. You can do both dry sanding and wet sanding to get rid of the bubbles, and dust nibs from the final coat. However, you will have to use the right type of sandpaper to get the best results and not hamper the smooth areas.