Wetsanding for beginners


If you are at all nervous about taking sandpaper to your new car there is a reason. The results shown here are unusual for a newbie at wet sanding. I spoke with many people in the auto body industry, before I started.

If you don’t feel confident in your ability to use a high speed rotary buffer on your paint then play it safe and do not attempt.

However, with a moderate amount of practice, there is no reason a good do it yourself-er can’t do this.


1. A good rotary buffer. Do not, under any circumstances, attempt to retrofit a buffing pad to an angle grinder. They spin way too fast.
2. Foam cutting pad. I prefer the yellow Buff and Shine brand.
3. A foam polishing pad, I prefer the gray Buff and Shine brand.
4. Wet sandpaper, 2500 grit. (3M Imperial 401Q) has the best bite and lasts a long time. You will need 20-40 sheets.

5. 1 Qt bottle of 3M Perfect-it II Rubbing Compound
6. 1 Qt bottle of 3M Perfect-it foam polishing pad glaze. This is the kind for dark cars, I will use this for any color car, but am taking the advice of the professionals that I consulted.
7. A rubber sanding block, get a thin flexible one not the rigid palm sized jobs.

The clear on Nissan cars is *about* 4 mils thick, the peel is about .5-1 mil deep so you have some room, but not much.
Wash your car with Dawn soap to remove anything that is/could be stuck on.

You need to start with a very clean car, at least the panel you are working. Soak the sandpaper in a bucket of water for at least an hour before you begin. Fold the paper in half along the long edge to make a square and wrap it around the block. Dip the block into a bucket of clean water, and start sanding.

Keep the surface very wet and going in only one direction. You will want to go the direction that the wind travels down the car. *Do not go from across the hood, but from the bumper to the windshield, etc. You will start to feel the paper bite after a few swipes, press down about as hard as you would press on a polishing cloth when taking a coat of wax off. Do this for a few seconds using even pressure on the block and scrape the water away from the area with your bare sanding block. Don’t dig the paper in with the edge of the block, keep it flat. Look very closely at the mess you just made of your new paint job. You will notice that amid the scuffing there will be shiny parts. As you sand with the 2500, squeegee off the water with a bare sanding block and look at the paint every few seconds. When you see the shiny parts of the paint become little dots that are completely surrounded by dull paint, you are getting close.

Continue working about a 1 sq foot area until all the shiny spots are gone. The paint is now as flat as you are going to get it. STOP NOW!! Scrape the water off again and let it dry. Look deep into the paint, you should only see scratches in the last direction you were sanding. resist the temptation to sand out any more wavy stuff. If there are no more shiny spots then STOP!!

*** This step is for those of you who have never used a rotary buffer.*** If you have never used a rotary buffer before, you should acquaint yourself with it. Do this with the polishing (Gray) pad and the 3M glaze like on the hood or something. You’d be hard pressed to hurt the paint with this stuff. It’s like a high speed wax job. This is solely to get a feel for how it will handle because it (the buffer) will want to wander and if you catch an edge somewhere it will kick hard! Around edges, always buff so that the pad rotates from the middle of the material out. Don’t press down; let the buffer do the work. This is especially important with the Rubbing Compound.

Keep in mind that as the clear coat is applied it will pull away from edges and sharp corners making it thinner in these areas. Be careful!!!

After you have sanded the car, wash it, and dry it well.
Put on the cutting pad (yellow) and shake up the Rubbing Compound. If you have an adjustable buffer, set it to about 1400 rpm. Apply a decent amount of Rubbing Compound to the sanded area and spread it around with the pad, this will prevent the stuff from slinging everywhere. Don’t keep the buffer in one place for more than a second or two. Work it back and forth buffing ACROSS the sanding scratches.

The Compound is a unique substance. You will want to buff it until it dries and dusts off. If you have applied too much, it will goo up on the paint in big clumps, and you will need to use your thumb to “push” it off. As you buff it, it will start to dry, and turn to dust and fly away. At this point, you will STOP, and buff it no farther.

Check your work by giving the panel a thorough wipe down with a CLEAN damp cloth to remove the dust and give the area a good inspection. If there are no residual scratches proceed to the next step. If there are residual scratches in some spots, use a small amount of Rubbing Compound, and buff them out.

Wash your car again, and dry it very well.

Switch to the polishing (Gray) pad and shake up the Glaze really well. This time you will want to buff the car in the same direction as you sanded it, and opposite of the direction you used the Rubbing Compound. This will take you to a very high gloss and expose any remaining scratches you may not have seen before. You can work minor scratches out with the Glaze but it will take a while. This is the safe way to go, always use the LEAST abrasive compound you can get away with.

If you have any larger scratches left you can work them out with the Rubbing Compound and finish with the Glaze. Just remember to wipe down the work area between compounds and use the appropriate pad.

A few tips:
1. The water in your sanding bucket should stay really clean, change it out often. Your standby paper should stay submerged. Keep about 5 sheets at a time ready to go. The Imperial lasts a long time.
2. Don’t sand really fast, you will just be skimming across the water on the panel. Sanding slowly will give you faster results as it needs to bite into the paint.
3. Tape off all lights, and plastic parts.
4. The best way to get swirl marks out of older paint is to attack it just with the 3M and polishing pad. If you have an older car, try it, you’ll see!!
5. By accident, I found out that using the Glaze on glass, will remove etched in water spots, and get rid of the wiper paths on the windshield.