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Sanding is an important step when preparing the surface to touch up or apply a new coat of car paint. However, before you sand the surface, you must ask yourself; ‘what is the right sandpaper grit for car paint prep?’
While this may not seem essential, choosing the right sandpaper grit will help you get a smooth, shiny paint job. Unfortunately, finding the most effective grit sandpaper isn’t that simple, considering the several different types of sandpaper on the market. Not to mention that each type of sandpaper is suited for a different purpose.
More importantly, choosing the wrong option might end up leaving deep scratches on your vehicle’s bodywork or even damaging the paintwork beyond repair.
Don’t worry though! In this post, we’ll look at the different types of sandpaper grit available and the job each option is best suited for. That way, you can easily find the ideal sandpaper grit for your project!
Let’s get into it!
Recommended car sanding applications for different sandpaper grit sizes
First of all, sandpaper grit is the number of abrasive particles contained in 1 sq inch of a sandpaper sheet. A lower number indicates that the sandpaper has fewer abrasives per sq. inch, making it rougher/coarser.
On the other hand, a higher number shows that the sandpaper has more abrasives, making it finer.
The ideal sandpaper grit depends on the repair project you’re undertaking. For instance, lower grit sandpapers are suitable for touch jobs like stripping car paint. While high grit sandpapers are ideal for clear coat coats.
In short, there are many types of sanding applications in the automotive industry. More importantly, this means that there is not just one type of sandpaper grit needed for the job.
The most common sandpaper grit options you’re likely to encounter in your car project are;
40- 80 grit sandpaper
40-grit sandpaper is very rough and usually leaves visible sanding marks on the surface. For that, it’s not recommended to remove minor clear coat scratches and other similar applications. However, it’s an excellent option for shaping body filler and rough sanding the bodywork to bare metal.
80-grit sandpaper is a step below the 40-grit sandpaper in terms of coarseness. This makes it a great starting point for sanding the filler after it has dried out. For instance, you can use it to smoothen out the body filler before applying the primer.
120 – 180 grit sandpaper
120-grit sandpaper is ideal for flattening out scratches from heavier grit sandpaper since it’s as rough. Specialists use it to finish off the filler after the 80-grit sandpaper has done most of the smoothening work.
On the other hand, a 180-grit sandpaper is the coarsest sandpaper option you can use on the auto body. However, you should not use it directly on car paint. Instead, it is well suited for sanding the spot putty and feathering edges of the body filler.
In addition, you can use it to get rid of light rust with minimal scratching.
320 – 400 grit sandpaper
This sandpaper grit range is much finer than the ones we previously mentioned. For that, sandpapers within this grit range are excellent for leveling and sanding the filler before applying the primer.
However, they are not suitable for removing or shaping imperfections. In addition, 320-grit sandpapers are commonly used with an electric belt sander or sanding block. 400-grit options are ideal for polishing surfaces.
600 – 800 grit sandpaper
600 – 800 grit sandpapers are excellent for sanding surface imperfections in the primer layer before you apply the base coat/paint. Start with the low-grit end (600 grit) and slowly work your way up to the finer 800-grit sandpaper.
1000 – 1200 grit sandpaper
This sandpaper grit range is perfect for removing base coat imperfections. Also, you can use it to sand sensitive surfaces like plastic. The best way to use these sandpapers is through the wet sanding technique.
Wet sanding involves soaking the sandpaper and spraying the surface with water during the sanding process to prevent clogging.
On the downside, this sandpaper grit range still leaves minor scratches on the car’s surface. However, these scratches are relatively easy to remove with 1500 – 2000 grit sandpaper before you apply the clear coat.
1500 – 2000 grit sandpaper
As mentioned above, one notable drawback of the finer 1200-grit sandpaper is that it will still leave marks. Luckily, you can use 1500 – 2000 grit sandpaper to smooth out these scratches and other surface imperfections on the base coat before and after applying the clear coat.
It’s recommended that you use the wet-sanding technique when working with 1500 – 2000 grit sandpaper for the best results. This involves soaking the sandpaper in cold water for about 10 to 15 min, before wrapping it around a backing pad or sanding block.
In addition, spray the area you’re working on with water and add a few drops of dish soap to keep it slippery.
What sandpaper grit to use on different layers of car paint?
Now that you’re well acquainted with the different types of sandpaper grits you can use for various car painting projects, let’s look at the best option for each car paint layer.
Any sandpaper below or around 500 grit is ideal for quickly sanding the primer layer and removing the upper car paint surfaces. Specifically, 320-grit sandpaper sheets are the coarsest option you can use to sand the car surface before you apply the primer.
However, you can use 180 or 240-grit sandpaper to remove rust and other types of corrosion before you sand the surface with 320-grit sandpaper.
Afterward, you can switch to the finer grit sandpaper sheets when preparing the surface for the primer.
Similarly, you should switch to the finer 600 – 800 grit sandpaper after applying the primer to remove bubbles, bumps, and imperfections before applying car paint.
As you progress with your car painting job, you’ll need finer-grit sandpaper for the best results. 1000 – 1200 grit sandpaper sheets are ideal for smoothening and preparing the surface for the 2nd and 3rd layers of paint after applying the base coat.
On the issue of dry vs wet sanding, the best option when sanding the base coat will depend on the type of touch-up paint you’re working on. For instance, if you’re dealing with waterborne car paint, wet sanding isn’t recommended as you may end up removing the car paint.
The clear coat is the final layer that tops off the car’s colored or base coat to protect it from various elements and provide the desired level of shine. Therefore, you have to be very careful when choosing the sandpaper grit to use to remove surface imperfections on this car paint layer.
That said, 1500 grit is a good starting point, but you still need to be cautious to avoid sanding the clear coat too much. For that, you should consider using the 200-grit sandpaper and work your way up to the 2500- and 3000-grit sandpaper for that ultra-fine finishing touch.
What is the recommended sandpaper material for sanding car paint?
Aluminum oxide is one of the most popular abrasive materials for sandpapers intended for automotive applications. This is because it fragments in a way that retains its cutting edges during the sanding process, thus allowing you to use the sanding disk or belt for longer.
In addition, aluminum oxide is available in different coating options. However, the closed-coat coating is the recommended option since its grains cover up to 95 percent of the disc surface, allowing it to leave a smooth surface on both non-ferrous and ferrous metals.
Lastly, there are many aluminum oxide sanding discs for auto body repair in the market that are specifically designed for automotive applications. In most cases, the best sandpapers for car paint have a waterproof backing with a thick hoop & loop design for improved performance quality and added durability.
Best of all, they provide a fast cut, long disc life, and professional results, giving you optimal returns on your investment!
Can you use a rubbing compound to sand car paint?
Although a rubbing compound isn’t sandpaper and does not even have a grit number, you can use it to remove clear coat imperfections and smoothen the surface after using the 2000-grit sandpaper.
Best of all, a rubbing compound brings back the shine to the car paint after sanding the surface.
Knowing how to choose the right sandpaper grit for your car paint project will help you achieve professional results. In addition, this will ensure that your freshly painted car exterior has the perfect shine and level of smoothness.
More notably, the best sandpaper grit for car paint may vary depending on the surface you want to paint, the condition of the exterior, and the nature of your car painting project.
At the same time, you may want to choose the sandpaper depending on whether you plan to wet- or dry-sand the car surface.
Read next: Why does my car’s paint have bubbles?