When it comes to finishing a surface, sanding is usually advised to achieve a good finish but not every finish needs to be sanded. So you may be wondering – do you need to sand between coats of polycrylic? Here is the answer to that.
You need to sand lightly between coats of polycrylic to remove fine particles of dust and grain that settle on the polycrylic finish. Sanding also helps to strip the finish lightly to improve adhesion.
But that’s not all. There is more to know about sanding between coats of polycrylic and this post digs right into the topic. Let’s take a closer look.
What Happens If You Don’t Sand Between Coats Of Polycrylic?
If you don’t sand between coats of polycrylic finish, the topcoats wouldn’t adhere properly to the base coats because the base coat will be riddled with grain and dust particles. You will also notice uneven application if you don’t sand between coats of polycrylic finish.
Polycrylic finish like every other finish or paint is a dust magnet. After the first coat of polycrylic finish is applied on the surface, it would take over an hour for the first coat to be dry enough for another coat.
As the coat of polycrylic paint dries, dust will settle on it. Even if you paint in a dust-free environment, you will still notice grains and bumps in the finish after it has dried.
The bumps and grains appear as a result of improper mixing of the paint, bad brush strokes, and bristles on the brush. It’s almost impossible not to notice any grain or bump when a coat of polycrylic finish dries. So you need to sand between each coat of polycrylic to get rid of these bumps, grains, and dust particles.
If you don’t sand, the dust particles and grains, it will make it impossible for the next coat you apply to adhere properly to the base coat.
The bumps will also cause an uneven application of polycrylic finish. Which for the record isn’t a thick finish. Polycrylic finish is thin so you need a very even surface before applying the finish.
If not, you will experience runs and drips. Not sanding between each coat will also cause paint wastage and subsequently, a bad paint job.
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Do You Need To Sand Paint Before Applying Polycrylic?
You need to sand paint with very fine sandpaper before applying polycrylic to allow even application and a smooth result. Sanding will strip the paint lightly, increase inter-coat adhesion, and prevent drips.
Polycrylic is very common as a finish. It is usually applied after a surface has been painted or stained. It gives the surface an extra layer of protection against harsh weather and scratches. That said, you need to sand the paint before applying polycrylic to allow the poly to sit well and adhere properly to the painted surface.
Polycrylic finish doesn’t have the best adhesive qualities. The finish is also very thin and light which makes it difficult to use it on vertical surfaces. The thin nature of the finish also makes it difficult for it to adhere to paint without sanding first.
So, the polycrylic finish needs something to hold on to or bite into so it can stick well. This is why it’s very important to sand paint lightly with fine-grit sandpaper before applying polycrylic finish.
Sanding will help to strip the surface lightly so the polycrylic finish can sit well. Think of it as increasing the adhesive qualities of the paint so the polycrylic finish can stick.
After sanding the paint, you should get rid of the dust with a shop vac. This will allow the painted surface to be smooth. As stated earlier, polycrylic finish is light and thin so it wouldn’t cover any gouges or dents in the painted surface after being applied.
If the paint is riddled with dents, gouges, or imperfections, it’s better to get rid of them before applying the polycrylic. To achieve a smooth polycrylic finish, the paint has to be smooth too.
Should I Sand The Last Coat Of Polycrylic?
You don’t need to sand the last coat of polycrylic finish. You just need to apply the last coat evenly and leave the finish to dry. Sanding the final coat of polycrylic finish will make the finish scuffed or cloudy.
Polycrylic finish needs to be sanded but only while applying multiple coats of the finish. When you have applied the final coat of polycrylic finish, you don’t need to sand the finish. You only need to sand between coats.
If you sand the final coat of polycrylic finish, the finish will look scuffed and old. This is because the polycrylic finish is very light and thin. So sanding the final coat will damage the thin polycrylic finish especially if you are using coarse or medium-grit sandpaper.
Painters sometimes sand the final coat if the coat has many bumps and imperfections. Even though sanding the final coat of polycrylic finish isn’t advised
But to sand the final coat of polycrylic finish, painters use very fine-grit sandpaper like 600-grit sandpaper. The finish usually wouldn’t be sanded manually. A palm sander is usually used by painters to sand the final coat too.
This is however a task for an experienced professional. If you are a DIYer or a beginner, I wouldn’t advise you to sand the final coat of polycrylic finish by yourself.
But if you have applied the final coat of polycrylic finish on the surface and you can notice a few bumps and grains, you can smoothen it by either wet sanding or dry sanding. Let’s check out how to do this in detail.
Related Read: What Happens If You Don’t Sand Polyurethane Paint?
How To Smoothen The Final Coat Of Polycrylic Finish?
Polycrylic finish usually doesn’t need any sanding because the finish is thin and if applied correctly, will give a smooth finish. However, if you have applied the final coat of polycrylic finish and you still want to smoothen it, you can do that by either dry sanding or wet sanding.
How To Dry Sand The Final Coat Of Polycrylic Finish
To dry sand the final coat of polycrylic finish, you need to pick very fine-grit sandpaper. Any sandpaper above 600 grit is usually fine.
Before you sand, ensure the polycrylic finish is properly cured (dried). Polycrylic finish dries quickly and can dry to rough within an hour. This doesn’t mean you can sand it. It would take at least 2 hours before you can sand the polycrylic finish. You should also put on breathing protection because dry sanding produces dust and sometimes, toxic fumes.
To sand, all you need to do is make a complete wipe on the polycrylic finish. Do not scrub or apply pressure. You just need to move the fine-grit sandpaper over the finish in one swipe. Like you are wiping a stain off a glass surface.
If you apply too much pressure, you might damage the finish because polycrylic finish is very thin. Ensure to use only fine-grit sandpaper. Any sandpaper less than 400 grit can scar the surface and make it look cloudy.
How To Wet Sand The Final Coat Of Polycrylic Finish
To wet sand the final coat of polycrylic finish, you need to ensure the finish has cured completely.
You should also apply an extra layer or two of polycrylic finish. Usually, 3 coats of polycrylic finish are enough on a surface. But, wet sanding involves using fine-grit sandpaper and a liquid substance which in most cases might not be water. So to be on the safe side, you should apply at least an extra layer or coat of polycrylic finish on the previous 3 coats so you don’t scar the finish.
To wet sand, start by spraying the finish with mineral spirits or an alcohol-based solvent. You can also use water since polycrylic finish is water-based. Any of these will do.
When you have sprayed the polycrylic finish, use fine-grit sandpaper like 600 grit sandpaper to swipe the surface twice. This is why it is advised to add an extra layer of polycrylic finish.
While dry sanding will only require one swipe, wet sanding will require at least an extra swipe to achieve a smooth finish. So the extra coat of polycrylic finish will serve as a protective layer.
The advantage of wet sanding is that it doesn’t produce any dust or toxic fumes in the air as opposed to dry sanding. Any of the two methods above will smoothen the polycrylic finish properly. But remember, you usually wouldn’t need to even sand the final coat of polycrylic finish. But if you want to, you know how to go about it.
Related Read: Can You Sand Water-Based Paint?
Can You Paint Over Polycrylic Without Sanding?
You should always sand polycrylic finish before painting over it. Sanding will ensure the new coat of paint applied sticks to the poly properly. That’s because polyurethane has a slick surface that doesn’t allow the paint to sit well.
Polycrylic finish is water-based and it has a slick finish. The finish and look of the final coat of polycrylic finish make it difficult for paint to adhere or stick to it without sanding first.
The fact that the polycrylic finish is also water-based means that you can’t apply oil-based paint on the polycrylic finish. Doing so will cause the new coat of paint to peel and come off sooner than later. The new coat of paint will also not have a smooth appearance after it has been applied.
To paint over polycrylic finish, it is best to go with a water-based paint because polycrylic finish is usually water-based. Using water-based paint over polycrylic finish will ensure that the paint is durable and smooth.
But to use water-based paint, you still need to sand. Polycrylic finish after being applied will still have a few bumps and dirt particles. You need to get rid of these bumps and dirt to allow the new coat of paint to stick well to the surface.
Sanding the polycrylic finish before painting over it should be done using fine-grit sandpaper. Sanding here doesn’t mean stripping the finish.
What you need to do is just to scar the finish lightly so the new coat of paint has something to adhere to. So use fine-grit sandpaper like 400 grit or above to sand polycrylic finish before applying a new coat of paint over it.
How Many Coats Of Polycrylic Do I Need?
You need 3 coats of polycrylic finish on a surface to give the surface increased durability and resistance against harsh weather, handling, and scratches.
Applying fewer than 3 coats of polycrylic finish on the surface wouldn’t be enough because polycrylic finish is light snd thin. Also, applying more than 3 coats of polycrylic finish on the surface will be too thick and this can gouge the wood and even make the finish ugly.
Polycrylic finish is applied after painting a surface to give the wooden surface increased durability. But polycrylic is thin and light. One main reason for the thin nature is because the paint is water-based and not oil-based.
Since the finish is thin, you need multiple coats of the finish on the surface. The recommended number of coats is 3 on a wooden surface. More or less than 3 coats of polycrylic paint will not give you the look or finish that is needed.
Related Read: How Long Should Stain Dry Before Sanding?
Overall, sanding between coats of polycrylic finish is a great way to boost the adhesive qualities and finish of the poly. If you don’t sand, the poly wouldn’t stick well and this means that the poly would start to peel off after a while.
You just need to need 3 coats of polycrylic finish on a wooden surface but ensure to sand between each coat and leave the final coat without sanding it. When the poly is fully dry, you will have an extra protective layer of finish on your stained surface.
So there you have it. If you liked this post, ensure to check out others like it on this website for more painting tips. Have a nice day.