Sanding Between Cleat Coats – Necessary? And How to Do?

Sanding is a crucial aspect of a paint job as it helps to get that smooth surface that looks way better than it would if it was non-sanded. If you want your clear coats to bond properly when applying them, then you should sand in between them.

Is it necessary to sand between clear coats?

For different reasons, some people try to discourage sanding between clear coats. However, when dealing with coats of polyurethane, then it is recommended that you sand between the clear coats. In fact, for some polyurethanes, it is not just recommended, it is necessary.

Here are a few advantages to sanding:

1) Adhesion

When painting furniture or whatever, you want to ensure that there is adhesion between the two coats. Or else, the layers will begin to flake off, giving your work an unsightly appearance.

If you do not sand between the clear coats, as soon as your project gets exposed to humidity, your work becomes rough. You may end up needing to reapply the clear coats every year rather than the usual 4 to 5 years

2) Low-quality Paint

The quality of paint you use also influences whether or not you need to sand between clear coats. When you use cheap, low-quality paint, there is a high chance of getting bubbles, drips, roller imperfections, and brush marks.

This is because the paints do not have the necessary additives to give you a smooth finish. When using paints like this, you need to sand in between the coats. However, irrespective of the paint quality, if the surface you are working on does not look smooth, then you need to sand it.

Some people would rather use a foam brush, but foam brushes only help to remove brush marks and not the other defects. At first, you may be tempted to ignore these blemishes, but they tend to stand out once they are stained.

In a nutshell, sanding between clear coats gives you a smooth surface and attracts less dirt, making it easier to maintain.

Can You Sand and Reapply the Clear Coat?

Reapplying a clear coat after sanding away the old clear coat is possible. All you have to do is to wait until the old clear coat is completely removed, then you can apply a new one.

How Long Should You Wait Before Sanding?

There is no specific answer to this, as it is mainly dependent on the level of humidity in your work area. Usually, one needs to wait for some hours to allow the stain to dry before sanding. For hot areas, water-based coats may take longer to dry than in humid areas.

To be safe, we recommend waiting at least 2 hours before sanding when using water-based coats. For oil-based coats, you should wait for 5 hours. The most important thing is to sand between coats only after the first coat is completely dry.

Sand Like a Pro

Usually, we recommend getting a professional to do this for you. But since sanding is the easiest part of a paint job, we reckon it is something you can do if you’ve come this far.

Light Sanding

Sanding between coats requires a light kind of sanding. You don’t want to sand through the finish that you have applied to your work. The main objective should be to remove roughness. Modern clear coats are designed to protect undercoats from UV rays.

This is done to prevent color fading. So, while sanding you may want to be careful not to compromise the clear coat’s ability to block UV rays. You could also try wet sanding clear coats with fine sandpaper.

Here are some tips on how to sand like a pro:

  • Long, even strokes: When sanding, you want to ensure that your strokes are in one direction only and that they are done evenly. If the strokes are done randomly or circularly, you may end up having an uneven surface.
  • Sandpaper grade: If you are working with different types of wood or on a large surface, we recommend going for high-quality sandpaper that won’t wear out quickly. Using low-quality sandpapers may mar your project or give you an unprofessional finish when you’re done.
  • Joints: While sanding you want to avoid joints. Sanding around the joints could make it rise higher than the level of the surrounding area.
  • When you are done sanding the clear coat surface, vacuum the surface area. Try to remove every trace of dirt or dust. Once you are sure that the surface is clean, you can go on to apply the next clear coat

What Kind of Sandpaper Should You Use?

As far as sanding between clear coats goes, the recommended sandpaper is 220- to 400-grit sandpaper. The 220-grit implies that for every square inch, there are close to 220 particles.

Although 220-grit sandpaper is coarse enough for the job, you could also use 320-grit sandpaper since there isn’t much difference. 400-grit sandpaper also works but it is known to wear out too quickly.

Wet Sanding vs Dry Sanding

Wet sanding is a method of sanding that requires you to add water as a form of lubrication while sanding. The lubricant makes the sanding process less rough.

Dry sanding on the other hand is a much quicker method and is known to remove more materials than wet sanding. This method makes use of sandpapers with less grit than wet sanding and can be done using your hand or a power tool.

How to Wet Sand Between Clear Coats

Wet sanding is a much more fun way to sand between clear coats. It is also more comfortable and less prone to mistakes.

You should use wet sanding when you require a super smooth finish or when you are trying to avoid a huge mess during sanding. Here are a few tips on wet sanding furniture:

  • Soak 1200-grit sandpaper in water for a few minutes. As you wait for the sandpaper to soak, you could use masking tapes to cover up areas of your project that you don’t need to sand. These areas could include the joints, edges, and moldings.
  • When your sandpaper has soaked for about 10 minutes, wrap it around a sanding block. You could go on to wet the surface you plan on sanding. Do the wetting with a spray bottle to control the amount of water you’re pouring on the surface.
  • You can begin the sanding by applying firm pressure to the sanding block and moving it in a linear motion. This way you can see the sanding scratches.
  • Remember to keep the area you are sanding moist by spraying water on it now and then. When you notice the water on the surface becoming milky, wipe it, dry it and check for signs of wear. If there is none, you can continue with your sanding.
  • You can use 1500-grit sandpaper, followed by 2000-grit sandpaper to remove the scratches left by the 1200-grit sandpaper. Remember to keep wetting the surface as you sand. At the end of your sanding, you should have a surface that looks chalky and evenly dull.
  • Lastly, you can apply polish to the surface and buff it up. This way you can restore the surface’s shine.

How to Dry Sand Between Clear Coats

If you choose to dry sand between your clear coats, here is a step-by-step guide:

  • Use sandpaper between 220 and 400 grit (depending on what you want), a tack cloth, polyurethane, and a paintbrush.
  • First, you need to wait for your first clear coat to dry. If you are using polyurethane, then you may have to wait for 24 hours in some cases. It all depends on the temperature and humidity level at your location.
  • When your clear coat is dry, fold your sandpaper to fit perfectly into your hands. Lightly sand the surface using the grit side in a linear motion. To get the best result, you want to sand in the same direction as the wood grain.
  • When you are done sanding, you can clean the surface with a tack cloth and proceed to apply the second clear coat of urethane. Like before, you should wait until the second coat is completely dry.
  • Once the second surface is dry, you can proceed to sand it and repeat the same steps you followed for the first clear coat.
  • Remember not to be too hasty to sand a clear coat surface before it dries. If you do so, your sandpaper will become clogged easily.

Conclusion

The goal of sanding between clear coats is to have a smooth finish when you are done with your painting process. Whether you wet sand or dry sand, make sure to exercise the required caution and make use of the appropriate tools. Sanding between clear coats is a necessary but delicate aspect of giving your project a pleasant appearance.

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