Sandpaper Selection & Grit Guide for Auto Body Work

When the time comes to repaint a car, the task is more complex than just applying a new coat above the older paint job. In most cases, it’s best to remove the paint currently on the vehicle and start from square one.

Therefore, any car owner considering a new paint job should at least understand the grit intensities on the automotive sandpaper grit chart. Whether you plan on doing it yourself or bringing your vehicle to a professional, knowing what goes into auto body work can help you to determine exactly what your car needs.

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Flap Disc Sandpaper Grit Chart For Auto Body Work

Flap discs are grinding wheels that use layered flaps of coated abrasive to sand down surfaces. They’re great tools for removing rust and polishing and shaping metal. They’re different from flap wheels, which are meant for harder-to-access areas like the insides of pipes or tubes. Visually, the difference is obvious — the flaps on flap discs face downwards while those on a flap wheel face directly outward.

Here are a few of the benefits of using flap discs for your project:

  • Versatile: Flap discs can perform well even on bumpy or uneven surfaces.
  • Cooler functioning temperature: They produce less heat than other abrasive tools, which reduces the risk of leaving behind scorch marks.
  • Lower vibration: Because they vibrate less than grinding wheels, flap discs generate less noise and allow for more comfortable operation.
  • Exceptional results: Flap discs provide a better overall finish with less gouging than other mechanical abrasive tools.

Flap discs come in several different materials:

  • Zirc
  • Zirconium
  • Ceramic
  • Aluminum oxide

The chart below breaks down each grit of flap disc available from National Abrasives, Inc.:

Grit Breakdown: Which Sandpaper Is Right for Your Project?

Before beginning work on a car, it’s essential to know which grit size you need to get each task done. In most situations, you’ll start with a rough grit and work your way up to increasingly smoother grits as you move on to the next stage of the project, depending on the sanding application.

You can tell the coarseness of a sandpaper’s grit by checking its number. Lower numbers indicate a coarser grit, while higher numbers indicate finer grits. Here, we’ll explain which grit is right for each stage of a paint job and why.

Extra Coarse: 24-Grit to 36-Grit

Extra Coarse: 24-Grit to 36-Grit

Aside from grinding discs, sandpapers in the 24 to 36 range are the roughest of all grits. Typically, you’d use a grit of this intensity in projects where rough edges have formed along a panel.

For instance, if a car has been grazed along the side by a tree, a 24-grit piece of sandpaper could help even out the roughness. However, sandpaper of this intensity could leave needlessly rough scratches on an even, smooth coat of paint. Therefore, you should reserve the use of this grit on an automobile for extreme cases.

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Sandpaper in the 24 to 36-grit range is most appropriate for projects where the automobile has rough areas along the surface that need to be flattened out. For example, if you have an older car that has been given numerous overcoats, to the point where some of the layers have worn in places over time, the overall surfaces can be an inconsistent, caked-on mess. Not only will the car be tough to sand down to its metal, but there will also be certain spots that will need more intense sanding than other spots. This is when grits in the 30s range are most useful.

Once the caked-on paint has been largely stripped with a 24 or 36-grit sandpaper, you’ll then need to smooth out those areas with a higher-grit, less intense sandpaper. All that said, auto-sanding projects of this intensity are not the norm. Therefore, if you’re wondering what grit sandpaper to use for a car, the answer in most cases would be somewhere above this grit range.

Pro Tip: If you’re sanding by hand, make sure to use a sanding block. Your hand places uneven pressure on the sheet, which can cause imperfections in the car’s surface. Wrapping a piece of sandpaper around a sanding block helps to provide even pressure along the length of the sheet — the difference in sanding quality will be immediately noticeable.

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Sandpaper Sheets for Auto Work:

Coarse: 40-Grit

As with sandpaper grits in the 30s range, 40-grit sandpaper has large grains that leave rough streaks along painted metals. As such, 40 grit is primarily a sandpaper that should be confined to auto surfaces that require high-intensity sanding.

On the automotive sandpaper grit chart, 40-grit is generally recommended for cars, trucks and vans that have been treated to several overlying paint jobs over the years. Alternately, 40-grit sandpaper can be useful along spots of a vehicle where the surface has been grazed by falling objects, in which case a touch-up might ultimately be necessary.

Another use for 40-grit sandpaper is rust removal. Even though rusting doesn’t occur on all vehicles, cars parked outdoors in times of rain, snow and hail are sometimes vulnerable, especially when moisture makes its way through cracks in the paint. In any case, rust is cancerous to metal surfaces and must be stopped the moment it begins forming on the panel of a vehicle. If it’s not stopped, rust can eat holes through panels of the vehicle’s body, and ultimately require a costlier set of repairs.

With a 40-grit piece of sandpaper, rust can be rubbed away before it spreads. Afterward, you’ll also want to smooth out the affected area with a higher-grit sandpaper, and then seal off the spot with a paint touch-up.

Pro Tip: You should always take precautions to prevent injury when stripping paint from your car, especially if you plan to use chemical treatments. When you begin the paint stripping process, you should wear long, thick clothing made of fabrics like denim. Additionally, a mask and a pair of heavy-duty work gloves are essential for any project.

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Medium: 80-Grit

Medium: 80-Grit

In contrast to sandpapers in the 32- to 40-grit range, 80-grit sandpaper is gentler on the surface of vehicle panels. As such, 80-grit can be applied to the hood, roof or door panels of a car or van without leaving rough streaks.

However, light streaking will still be present if you apply heavy force. Therefore, the use of 80-grit sandpaper on a vehicle will usually need to be followed by a smooth-out sanding with a higher-grit sandpaper. Ultimately, 80-grit is best used on vehicles that need considerable sanding in select areas, but without the roughness of lower-grit options.

An 80-grit piece of sandpaper could come in most useful on cars with more than one prior paint job, as well as vehicles with light corrosion around the edges. For example, a car that has a five-year-old paint job over an earlier, initial coat of paint might be difficult to sand with higher-grit sandpaper. On the other hand, 80-grit could more easily work through the layers of paint and primer to reveal the metal surface.

Likewise, light rust along the lower edges of the doors could easily be sanded off with 80-grit sandpaper.

When people ask which sandpaper grit is best for a car, 80-grit wouldn’t necessarily be recommended for a newer vehicle with a single, even coat of paint. However, any car that needs intense sanding, without the super-intensity of low grits, is advised to try 80-grit paper.

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Sandpaper Sheets for Auto Work:

Fine: 150-Grit

The automotive sandpaper grit chart gets smoother with 150-grit, which leaves fine sanding marks on painted metals. 150-grit lacks the intensity for smoothing out nicks and stripping away multiple layers of paint. In fact, 150-grit sandpaper is mostly for feathering areas that have already been sanded with a lower-intensity grit.

For example, when the rusted portion of an auto-body panel has been sanded with a 32 or 40-grit piece of sandpaper, 150-grit is an ideal option for smoothing out the rough grooves that might exist at certain spots.

On cars that have a smooth, single layer of paint, 150-grit sandpaper can do an adequate job of stripping the paint to reveal the metal surface. In some cases, there might be little, if any, need for smoothing out rough grains with sandpaper of an even lower intensity. On panels that only need touching up in a certain spot, 150-grit will often be the perfect choice for smoothing out the edges of the crack or chip in an otherwise good coat of paint.

When people ask about what grit sandpaper to use when painting a car, 150-grit is one of the more popular recommendations. Consider using a palm sander with 150-grit sandpaper to reduce the manual effort.

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Very Fine: 240-Grit

When you get into the 200 range, sandpaper becomes smoother, yet stronger, than any of the lower-grit options. Therefore, a 240-grit piece of sandpaper can be used to easily strip an automobile panel of all paint. The sanding can be accomplished without the blunt streaks that a 32-grit would leave in its path. As such, 240-grit is the first level of sandpaper to consider for a car, truck or van that has a smooth yet thick paint job without corrosion or damage.

Even if your car has a second paint job over the first, it’s fairly easy to strip away the paint and reveal the metal with 240-grit.

Vehicles built within the past three or four years likely have only had one paint job. Due to the car’s relatively young age, paint is unlikely to have cracked in any spots, and rust has not had the chance to take root anywhere. Therefore, the panels could easily be stripped to the bare metal with a 240-grit piece of sandpaper, and all with little or no need for a secondary grit.

When people ask what grit of sandpaper is suitable for a wet sanding primer, 240-grit is a popular answer, because a wet, folded 240 will generally offer durability during a sanding job.

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Extra Fine: 320-Grit

Extra Fine: 320-Grit

At this point along the wet sandpaper grit chart, the options are ideal for smooth buffering as well as the removal of thick paint. With a 320-grit piece of sandpaper, paint should come off the vehicle with evenly applied strokes of a disc. By the time you work a 320-grit through the paint, the shiny, silvery luster of the metal should come glaring to the surface. Thanks to the strength of 320-grit sandpaper, it’s a good option for cars or vans that have been treated with enamel or other hard coats.

A perfect example of how 320-grit sandpaper can work is when you want to turn a blue van red. Before you apply the new paint job, you’ll want to sand away the older blue coats. With 320-grit, the blue should come off smoothly and easily. Once all of the panels have been stripped, the surfaces should be smooth enough for a primer coat of the new paint.

Alternately, 320-grit could make it really easy to change out the paint on a single panel, such as a scratched door. As such, when people ask what grit sandpaper to use when painting a car, 320-grit is a good choice for large automobiles with thick coats of paint.

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Super Fine: 400-Grit

When it comes to finishing, the most popular option is 400-grit sandpaper. Before the new coat of paint is applied, 400-grit paper makes prepping smooth and easy. If there are any rough areas spotted along the surface or edges of a given panel, 400-grit could be used to smooth the metal out in a way that lower grits might be incapable of.

The best thing about 400-grit sandpaper is that, despite its strength, it’s fine enough to handle challenges along an auto-body surface without roughing up the metal.

When the question arises about what grit sandpaper is appropriate for a wet sanding primer, 400-grit is sometimes stressed as better for wet sanding than for dry sanding. The reasoning here is that, when dry, 400-grit tends to leave sand on the subject, which can be troublesome as far as finishing work is concerned. Therefore, while 400-grit is one of the most popular grits of sandpaper, it’s often used exclusively for wet sanding. As such, 400-grit is one of the most widespread options on the wet sandpaper grit chart.

Pro Tip: When you move up to higher-grit sandpaper, a great way to check your work is to run your hand along the surface of the vehicle and feel for imperfections. Your hand should be able to pick up tiny flaws that aren’t otherwise perceptible.

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Super Fine: 600-Grit

When it comes to correcting errors in soft layers of paint, 600-grit sandpaper makes the task relatively easy. Likewise, if paint runs out before a panel has been fully covered, the edges of the paint can be sanded smooth with a wet 600.

Basically, 600-grit sandpaper is a perfect option when you need to salvage the panels after a paint job has hit a snag. When you consider all the time and money that can slip down the drain when a vehicle-painting project doesn’t go as planned, 600-grit sandpaper is a lifesaver because it reduces complications.

For example, you might be painting a car with a unique color that has to be specially ordered, but end up with a bad passenger door or roof due to the paint running out when you’re 93% finished. Under other circumstances, you might have needed to do the paint job over again, yet still be at risk of running out along another part of the vehicle.

With 600-grit sandpaper, it needn’t be as costly or time-consuming, because the raw edges of an unfinished paint job can be sanded back for a recoat and will therefore be ready by the time a new supply of the same paint arrives.

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Sandpaper Sheets for Auto Work:

Ultra Fine: 1500-Grit to 4000-Grit

As far as color sanding and buffing is concerned, sanding discs in the 1500 to 4000 range are your ideal options.

Once a new coat of paint has been applied to a vehicle and given time to dry, a sandpaper disc in this range allows for a smooth and even finishing touch along areas of panels that might exhibit roughness or inconsistencies along the painted surfaces. That way, you won’t experience any significant setbacks if minor challenges occur, such as the discovery that dirt or hairs have been stuck to the surface under the paint.

The benefits of 1500 and 4000-grit sandpaper discs make it especially easy to paint larger automobiles. In the past, sanding down a van could take an entire day, if not longer. Likewise, redoing a door or hood on which dirt landed as the paint was drying could lead to further loss of money and hours.

Today, electric random orbital sanders make it possible to sand a van or a truck in a matter of hours, while mistakes can easily be eliminated in minutes with 1500 or 4000-grit sandpaper.

Pro Tip: When you’re sanding with grits 1500 and above, you need to use a wet sanding technique to ensure good results. Whether you use water or a detergent, the liquid will act as a lubricant for the sandpaper, removing tiny particles as you sand to prevent the paper from getting clogged.

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Buy Sandpaper From National Abrasives, Inc.

When it comes to sanding systems, Mirka is one of the world’s leading providers. Mirka’s products make it easier to refurbish older vehicles and make the exteriors shiny and new thanks to their commitment to automotive refinishing and closely related technologies.

As one of the leading suppliers of Mirka products, National Abrasives, Inc. is proud to be a convenient, one-stop source for a full range of sanders, accessories and other tools. With our secure, 24/7 ordering process, we offer free shipping on bulk orders, as well as price matching for anything you find in our inventory.

To learn more about what we have to offer, visits our sales pages today!
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*Updated February 02, 2022

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