Sandpaper grit is sized by a gauge number, with lower numbers signifying larger, coarser grits. For example, #24- or #40-grit sandpaper is a very coarse, rough sandpaper, while the #1,000-grit paper is extremely fine with very small abrasive particles.

The grit of sandpapers is a rating of the size of abrasive materials on the sandpaper. The higher grit number is equivalent to a finer abrasive, which creates smoother surface finishes. Lower grit numbers represent coarser abrasives that scrape off materials much quicker.

180 to 220 Grit Sandpaper: Finer grit sandpaper is great for removing the scratches left by coarser grits on unfinished wood and for lightly sanding between coats of paint. 320 to 400 Grit Sandpaper: Very fine grit sandpaper is used for light sanding between coats of finish and to sand metal and other hard surfaces.

Sandpaper Sheets are measured by the width x length x grit. That is, a 230 x 280 mm x 240 grit, is 230 mm wide x 280 mm in length, and 240 grit. Sandpaper Flap Wheels are measured by the diameter x width x shaft diameter x grit.

Use 60- or 80-grit for aggressive, fast wood removal. Use 100-grit for all-purpose sanding and 120 or 180 for the finest finish, but follow power-tool sanding with hand sanding. Power tools leave hidden scratches that show up later. And always sand parallel to the grain.

With that in mind, here are three ways to finish wood projects (meaning to get them nice and smooth) that don’t require sandpaper.

1. Scraping. This can be done with a knife held at 90 degrees to the wood, with a cabinet scraper or even a piece of broken glass in a pinch.
2. Burnishing. Rubbing the wood.
3. Sanding.

Dry sand using 180-grit sandpaper to remove rust or surface damage before moving on to a 320-grit paper to remove your previous 180-grit scratches. Whichever method that you decide, follow it up using 400- to 600-grit sandpaper to sand the paint to prep the existing paint surface for the new coatings to be applied.

When painting a vehicle, sandpaper can often be your best friend. Use low grit sandpaper such as 80 or 300 grit pieces to smooth out the scratches or imperfections in the surface of the vehicle. You should also spend some time practicing good wet sanding methods with 1000 or higher grit papers.

For headlights that are heavily oxidised and very cloudy, it’s good to start with 400-grit sandpaper (classed as super fine sandpaper). If your headlights aren’t too cloudy, then you can use 600-grit sandpaper instead. Before sanding, apply water (which acts as a lubricant) to the headlight and the sand paper.

Purchase 1200 or 1500 grit sandpaper.

1. Any less than 1200 grit sandpaper may produce scratches that are difficult to buff out.
2. The higher the grit number on the sandpaper, the finer the abrasive surface.

Wet sanding is used in home interior jobs, and it is effective in reducing a lot of dust in the process compared to dry sanding. The sanding dust gets wet and doesn’t ruin the paint later on. The sandpaper used for wet sanding also lasts a long time, but you have to keep rinsing it with water.

No, not a good idea because the adhesive that holds the grit onto ‘regular’ sandpaper is not waterproof and will release the grit when used for wet sanding. Always use the black-colored silicon carbide paper for wet sanding.

You can let the base dry and sand before you clear but that is not the way it’s meant to be applied. Ideally, you ultra-fine the clear and buff it to a glossy shine after you’ve applied it to a properly cured, unsanded base.

Wet-sand the base coat before starting the clear coat. If you wet-sand the base coat, wash the vehicle with soap and water after this step, not before. Once the base coat is smooth and clean, start spraying on about three to four layers of clear coat.

The clear coat should be wet-sanded with 400 grit sandpaper. The sanding steps help diminish the clear coat until the entire surface is smooth. The polishing helps smooth out the scratches made by the sandpaper.

The bad news is, you can’t just sand for adhesion and respray clear coat. You can sand for adhesion and spray a new coat of clear over the base, but it will never lock in, and it will always sit on top of the old clear at the edges. The new clear coat will never be as strong as the original and will fail much quicker.

The clear coat feeling coarse or leaving a sort of misty effect can be due to a few things such as the clear being applied too light, too far, or in high temperatures. Unfortunately you will need to sand the surface before applying clear coat in order to avoid cracking when applying a fresh coat of clear.

In order to paint clear on it again, you actually need to do some more sanding, scratching the surface even more. You want to hit the surface with some 1000 grit wet sanding. This will give the surface a little roughness, something for the new clear coat to adhere to.

Then take painter’s tape and tape off the area where you will be working. You should go about an inch past the clear coat damage. Use 800 grit sandpaper to sand the clear coat down and leave a surface area that is roughened up. As you work away from the damage make your sanding lighter.

Soak a sheet of 1200-grit wet/dry sandpaper in water for 10 minutes. While it is soaking, apply masking tape to areas you don’t want to sand, such as moldings and panel edges. Remove the sandpaper from the water and wrap it around a sanding block. Wet the area you’re going to sand by spraying water from a spray bottle.

320 to 400

We wet sand our primer prior to painting, we’ve been doing it in this manor for about 40 years and have never had a problem with moisture. Of course we allow the surface to dry well before painting. Wet sandpaper cuts more evenly because the residue from sanding does not collect on on the paper while sanding.

Unlike dry sanding, wet sanding is done not to shape a surface, but to remove the large scratches left by dry sanding. When done correctly, the surface will be slowly leveled out, and the scratches left behind will become smaller and smaller, until the light they reflect no longer makes them visible.

You don’t apply compound or polish. Compound and polish are an abrasive that will remove the sanding marks, making the paint shiny. If you’re doing it my hand you’re not going to get a great result. I’d say sanding then hand polishing what you’ve currently got will probably make it worse.

Wet sanding by hand is not a problem just time consuming. Buffing is best done with a rotary buffer. Most guys use a 7″ rotary for buffing.

Re: Help removing wet-sanding scratches – for a newbie You will have better success by sanding down to 3000 grit. After sanding with 3000 grit paper you should be seeing a dull shine and very little sanding marks. After sanding try Megs 105 with wool pad on a rotary then 205 with a white or black foam pad.

You need a machine. buffing by hand is quite difficult, more difficult than by machine. It’s a skill in itself, and if the paint is hard and defects significant – it can be next to impossible to get anywhere.