What grit sandpaper should I use before primer? When looking to sand a surface before applying primer, the best grit sandpaper to use is 320 to 400. Both these grits can effectively remove the existing primer and help you flatten the surface.
If applying Primer-Sealer over the Primer Surfacer, final sand the Primer Surfacer with the recommended grade paper according to the Primer-Sealer Product Data Sheet.
Finish sand between coats with a fine-grade (220-320) foam sanding pad or 400-grit sandpaper to improve smoothness and adhesion.
Ryan said that by taking a surface to 180 grit or finer before applying primer, top quality primers should fill the surface without issue. Problems arise only when a primer is asked for “too much work” and to fill a deeper surface, he said. Fillers and glazes can present similar issues.
120 is fine. I prime over 80 grit to 120 bodywork all the time with no shinkage. I feel 180 is to light for proper adhesion with primer.
Primer will fill in 180- to 320-grit sand scratches. Always stir and never shake your paint.
For heavy sanding and stripping, you need coarse sandpaper measuring 40- to 60-grit; for smoothing surfaces and removing small imperfections, choose 80- to 120-grit sandpaper.
The goal of sanding wood that has primer on it is to smooth down the grain that has risen while still leaving the primer intact so you do not lose the added adhesion that the primer will provide for the top coat. To sand wood with primer on it you should consider a finer grit sandpaper (like a 220 grit sand paper).
180 – 220 grit is primarily used for the sanding finish or to sand in-between coats. It is also great for distressing! There are instances where you can use 180 to 220-grit to rough up a piece in preparation for paint, but you do not typically use these grits until after your first coat.
320 grit is the best to use for dry block sanding 2K Urethane primer, it's both rough enough to be able to sand quickly and fine enough to not need much more after you're done.
Sanding sealer should be applied after the wood has been sanded down to a bare finish, but before the topcoat (such as paint). Sanding sealer is not recommended on stained surfaces because the sanding process will scuff away the stain.
Primer is used to create a base for the paint, improve adhesion, and prevent stains and bleeding. Sealer, on the other hand, is used to seal the surface and prevent the topcoat from being absorbed or bleeding through. Undercoat is used to cover imperfections and create a smooth surface for the topcoat to adhere to.
Sanding sealer always must be sanded down smooth after it has dried. Sanding sealer helps improve the condition of subsequent coats of paint or clear finish by sealing the wood pores.
My preference is to use 220 grit sandpaper and sand in the direction of the grain. You don't need to sand too hard, just enough to scuff up the surface and dull the shine.
As a general rule, if you don't sand the wood before painting then the applied paint could peel off after a while. This will only happen, however, if the new paint was applied to an already painted or sealed surface.
Once you've completed your last coat of primer, you should go ahead and sand before applying your first coat of base color. However, there is no reason at all to sand between coats of primer. It will only add more work to your plate with no visible benefits.
Sanding Your Car's Paint
1,500 grit is a good starting point, though you'll need to be cautious about sanding it off too much. It's better if you have 2,000 grit, at least, as you can then move up and up to 2,500 grit, and the final 3,000 grit for an ultra-fine finishing touch.
Very-fine (150-, 180- and 220-grit): This produces ultra-smooth surfaces on wood. People often use it to scuff-sand lacquer, polyurethane and other finishes before applying another coat. Extra-fine (320- and 360-grit): The first of the micro-abrasives, this is primarily for sanding finishes before polishing.
If you see any residual scratches, keep sanding. It can also help to lightly dampen the surface with mineral spirits or water. Summary: A good general rule for grit progression is to use 100 or 120 grit for initial sanding, 150 or 180 grit for the next pass, and 220 grit for the final pass.
Let the primer dry completely, then sand it down before painting. Use very fine 220-grit sandpaper, and apply light pressure to prevent gouging the primer. Remove the primer dust with a quick brush from the shop vacuum, followed by a light swipe of the tack cloth.
#180–#220 Grit: Fine
Sometimes, fine-grit sandpaper is used to roughen glossy paint in preparation for applying another coat. Bare wood that will be stained often should not be sanded with higher than 220-grit paper. Fine or ultra-fine sandpaper grits are used for furniture work.
Now you may be thinking "SAND AGAIN?!?" after just finishing the messy drywall stage, but a light sand with 150 or 180 grit sandpaper is very important. Whether you use a separate primer or self priming paint, both will raise the nap of the board making a slightly rough surface.
Our 1200 grit medium/fine sand paper works for wet or dry sanding. This flexible, silicon carbide abrasive paper is perfect for metals, glass, ceramic and stone, and features a waterproof packing to prevent disintegration during wet use.
Selecting the right grit sandpaper
For heavy sanding and stripping, you need coarse sandpaper measuring 40 to 60 grit; for smoothing surfaces and removing small imperfections, choose 80 to 120 grit sandpaper. For finishing surfaces smoothly, use extra fine sandpaper with 360 to 400grit.
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.