How to Sand a Car for Paint
Recently, we wrote a post on how to paint your car with auto body supplies. In it, we shared how important it is to prepare before your paint. We don’t want you to buy auto paint supplies just to waste it, so today we’re going deeper into the sanding phase of preparation.
Here’s what you need to do if you want to properly sand a car.
Make sure you pick up the following supplies before you get started:
- Wooden Sanding Board or…
- Rubber Sanding Blocks
- Wet/Dry Sanding Pads
- Auto Body Repair Tools
- Kitchen Sponges
- Rubber Squeegees
- A Bucket
- Low/Medium/and High Grit Sandpaper
- Safety Equipment (Facemask, Goggles)
Wash it Down
Before anything else, give the car a thorough wash using wax and grease remover. If you don’t, you’ll gum up your sanding pads with wax. That may not seem like much more than a simple annoyance but it could end up ruining your day.
When you sand a car, you not only strip the old paint off but you create tiny etches in the body that facilitate primer/paint adhesion. If you’ve got latent wax on the car and/or your sanding pads, the friction from sanding will cause the wax to fill in those etches. The result is poor adhesion and an ugly finish that you won’t know about until after you’re done painting.
A Quick Word about Gloves
Another surefire way to cause the kind problems you’ll only notice after you’re done is skipping on the gloves. Sure, they get sweaty and annoying, but gloves are absolutely essential. If you don’t use them, the salt and oils from your hands will end up on the car. Weeks after painting, the oil from your hands will actually cause the paint to bubble. The only way to fix that is to start all over again.
It’s important to decide from the beginning what your goal is in sanding. Are you going for adhesion or you taking it down to the bare metal? For cars with little to no body damage, you may be able to get away with sanding for adhesion. In that case, a medium to high grit sand paper should be sufficient.
Pro Tip: Using a bucket, hose, and/or a spray bottle, keep the car and sandpaper wet as you sand it down. This will keep loose paint particles from getting sanded into the paint and ruining your adhesion and final finish.
If you want to take the car down to the bare metal, you’ll want to start with a lower (rougher) grit. Otherwise, you’ll spend an entire day and a couple stacks of sandpaper getting all of the paint and primer off. Once you’ve done the heavy lifting, it makes sense to go over the car again with a medium grit to remove any scratches you may have left with the rough stuff.
You can use a sanding machine in either scenario, but the hands-on approach may be better for beginners. Load up your sanding block, grab it with both hands, and slowly work it along the flat surfaces of the car. Keep your strokes deliberate and even; nobody’s in a rush here. Attention to detail in your strokes will help you take the paint and primer off while keeping a nice, even surface.
That’s how to sand your car in a nutshell. Take your time and pay attention to the details. When you get done painting and stop to admire that perfect finish, you’ll be glad you spent the time needed to do it right.