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How do you get rid of brush strokes in polyurethane?

Author

Emma Miller

Updated on May 11, 2026

Thin your polyurethane with paint thinner, mixing it with a paint stir stick. When polyurethane is too thick, the brush marks hold their shape and don't settle out. Thinning the product provides a smoother finished surface. Experiment with different amounts of paint thinner to see what works best for you.

How do you fix brush marks on polyurethane?

Just dip the brush in and let it drain. You can also pad it on. Finally, for a fine finish you will need to wet sand with 600 grit and water with a drop of dishwasher detergent. Allow at least a week for the finish to cure.

How do you get rid of brush strokes on top coat?

Let the first coat dry for 24 hours, sand it lightly with 22D-grit sandpaper wrapped on a block, and remove the sanding dust with a cloth moistened with mineral spirits. Examine the varnish for brush marks. If you see any, sand again with 220-grit paper, and remove the dust.

How do you remove streaks from polyurethane?

Get a clean cloth and add some mineral spirit to it and wipe the surface to remove any dust and debris. Repeat the same wiping procedure until the blotching is gone and let the surface dry. Sand the surface with fine-grit sandpaper (220 grit) until the cloudiness disappears and until the polyurethane finish is removed.

Can you buff out brush marks in polyurethane?

*How Do I Remove Brush Strokes from the 3rd Coat of High Performance Polyurethane? Sand down the final finish with a 220-grit foam sanding pad, and then add another layer of General Finishes High Performance PolyurethaneTopcoat. Apply liberally than you did previously without heavy back-brushing.

Fixing Polyurethane Bubbles, Puddles, Runs and Brush marks

How do you get an even coat of polyurethane?

Use a Roller on Large, Flat Surfaces

  1. A 6-in. rollers lets you apply the poly fast and evenly. ...
  2. Don't freak out when you see the finish right after you lay it down. ...
  3. After each coat, re-dip the roller in mineral spirits and put it into a zippered plastic bag for the next coat and leave the wet tray to dry.

Do you sand the final coat of polyurethane?

No, you don't need to sand the final coat of polyurethane. The only time you should sand the final coat of polyurethane is if you haven't gotten a smooth finish. Different problems can occur when you apply polyurethane, such as dust nibs, bubbles, and streaks.

What do you do with a polyurethane brush between coats?

Let it soak between coats.

When you're done with the brush, rinse it a couple of times in used mineral spirits, then pure mineral spirits, removing the bulk of the solvent on newspaper each time.

Should I sand between coats of polyurethane?

Yes. Minwax Polyurethane should be sanded between coats. Sand with 320 grit sandpaper to get rid of any fine particles of dust that have settled on it while it was still wet. Sanding in this case not only allows for a smoother finish but can also help abrade the surface and increase inter-coat adhesion.

Can you buff out polyurethane?

Add a pea-sized amount of car paste wax to a polishing pad or cloth. Work in short, smooth motions until there are no visible scratches in the polyurethane. Move the pad in smooth, horizontal motions so you can apply an even coat of wax to the surface. You can also use a section of 0000 steel wool to buff the surface.

What is the best brush to apply polyurethane?

Synthetic bristle brushes are the most common option. The bristles are made with synthetic material, like nylon or polyester, which is better for applying water-based polyurethane. These brushes are also frequently used with latex-based paints.

Is it better to brush or roll polyurethane?

Don't use rollers or foam brushes—they create bubbles. Your brush will be easier to clean, and will go longer between cleanings, if its bristles are dipped first in mineral spirits, if you're using an oil-based poly, or in water, if the finish is water-based.

How do I get a smooth clear coat finish on wood?

The way to get the smoothest and best-feeling finish is to “rub out” the last coat using sandpaper and abrasive compounds. Methods of doing this are written about often. It's a mechanical procedure that doesn't differ all that much from sanding the wood.

Can you put too many coats of polyurethane?

Generally, more than 3 coats of poly doesn't do much good. It's really not needed nor recommended. Each additional coat needs to be buffed so you are kind of buffing off half of the previous layer. So 4 coats is more like 3.5 coats.

Will denatured alcohol clean polyurethane brush?

Simply wrap the brush to keep it clean, then soak it in denatured alcohol for several minutes before using the next time. To clean the brush, rinse it several times in clean denatured alcohol, shaking out as much of the liquid as possible between each rinse.

Does mineral spirits remove polyurethane?

Mineral spirits will not affect polyurethane, so a rejuvenator is needed for this. This is simply paint stripper thinned with solvent. It will soften the polyurethane so some of the top material can be wiped off. You cannot revive a finish if it is thin, flaky, checked or alligatored; you must strip it.

Can you use steel wool to sand between coats of polyurethane?

Using steel wool or sand paper allows you to create a uniform surface for the next coat of polyurethane, which generally looks nicer, more professionally, etc.

What grit sandpaper should I use for polyurethane?

Start with 120-grit sandpaper on refinished pieces and 80-grit on new wood. After sanding the entire surface thoroughly, wipe off the dust and all loose sandpaper grit with a clean cloth. Then, sand with 180-grit until you've removed all the marks left by the 120-grit, and the surface appears level.

How do you brush polyurethane without bubbles?

To avoid bubbles in water-based polyurethane, apply multiple thin coats using a quality synthetic polyurethane brush instead of a natural brush. And before applying polyurethane, dampen the brush with water to avoid bubbling, puddling, or running.

Should I use a foam brush for polyurethane?

Foam paintbrushes will work with almost any paint or polyurethane on any project. They are cheap enough to toss away, although they can be cleaned and reused several times. They hold the liquid without drips making them user friendly. Compare the price of foam and bristle brushes and you will be happily surprised.

Can I use a rag to apply polyurethane?

You can apply Minwax polyurethane with a rag. The type of material will determine how quickly it will dry and what you need to clean up afterward. Some wood finishes dry very quickly. Some may even have a water-based formula that makes them easier to clean up after applying.

How do I get a smooth finish with water-based polyurethane?

First use a degreaser cleaner like Formula 409 or Fantastik to clean away any buildup of grease or cooking oil. Scuff-sand the old finish with fine synthetic wool, then seal with Zinsser SealCoat. Sand the seal coat with fine synthetic wool, then brush on two to three coats of water-based poly to complete the job.

Is 2 coats of polyurethane enough?

2 coats of polyurethane are enough to protect the wood from moisture and contaminants. However, for added protection against water damage, about three or four coats of polyurethane would suffice.