Popular Sandpaper Grits Explained
36 Grit - If you don't count grinding discs the roughest paper I use is 36 grit. I use it in two configurations 2 3/4" X 17 1/2" and 8" round disks. This paper is used after fillers are cheese grated flat in order to achieve a level surface that is ready for polyester putty.
40 Grit - I buy this is small quantity to use very seldom for cutting down fillers that I want to have less of a scratch in prior to the next step. A couple of sheets lasts me a long time because I rarely use it.
80 Grit - This is found in my shop in 6" discs for the DA, 8" disks for my disk sander, 2 3/4" X 17 1/2" for the long sanding board and 2 3/4" x 25 yard roll of Stick-It paper. The roll is the best thing since sliced bread as far as I'm concerned, I use it on 4" and 8" blocks, on tubes for sanding in curved areas and it's great just to tear off a 3" piece and fold it in half to do little jobs with by hand. On the DA this 80 grit is used for cutting out scratches left from doing body work feathering out chips in paint. On the 8" disk sander it can be use for stripping off paint without tearing up the metal like 36 will. On blocks and boards it's the perfect grit for sanding polyester putty before your 2K or primer/filler is sprayed on.
220/240 Grit - 6" discs, 9" X 11" sheets (Dry & Wet), 2 3/4" X 25 yard roll...the disks are used on the DA to remove 80 scratches and finesse the feathering process. This grit has faded out over the last 15 years and is used much less in preparing the vehicle for paint because today's paint materials don't need this heavy of a scratch to bond to the surface and this heavy scratch will show through many bc/cc colors. However, if I'm planning on RE-coating with primer a second time I'll make fast work of the first primer coat with a properly folded piece of 220 wet. Proper paper folding can make the wet or dry paper last much longer but I digress.. I use the roll paper the same as the 80 on blocks and boards to achieve flatness and torn into smaller pieces for hand use. Right before applying my 2K primer I'll sand my filler, very lightly with 220 dry in order to soften the 80 scratches slightly.
320 Grit - 6 " discs and 9" X 11" sheets (Dry & Wet).. This is a must have for sanding under single stage paint that you plan on buffing or single stage paint that is a lighter color and less expensive paint job. Primer can also be cut with this grit quickly then followed by 400 wet that can be painted over by almost everything. I usually use this dry to sand a vehicle for overall painting. The same grit dry will leave LESS of a scratch than a wet paper.
400 Grit - 9" X 11" sheets (Dry & Wet)... I rarely use this material dry but I will sand a vehicle for an overall that will be painted a color that may easily show sand scratches (like a bc/cc silver) with 400 wet. Using this grit dry is a hassle because it fills with dust so quickly but wet I use this in "properly torn and folded" sheets to sand primers before painting. This is about the most coarse grit that you will want to sand under most bc/cc with in a wet paper.
600 Grit - 9" X 11" sheets (Wet)... Another handy grit that can be used if you must make corrections in soft paint or you're running out of paint and need to re shoot a panel you might hit it with 600 wet first.
1200/1500/2000 Grits - 5 1/2" x 9" & 9" X 11"(wet sheets) and 3M color sanding film in 6" discs. These are for color sanding after the paint is applied and hardened and is followed by buffing compound. Before 3M came along with the sanding film you had to sand the entire vehicle by hand, which could take an entire day or more, now with the 3M discs, an interface pad and the proper DA you can cut that labor time in half, to say nothing of all that arm motion.
Sandpaper Grading Systems
The size of the grit on sandpaper is measured using several different systems. In the USA we use the CAMI (Coated Abrasives Manufacturer's Institute) system. In Europe they use the FEPA (or P grade system). There is also measurement in inches and microns. I've put a conversion chart on this site in order that you get the sandpaper you want and/or you can judge the sandpaper you have.
Sanding Materials
Quantity and Pricing
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Grinding Products
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Small quantity kits are at the bottom of this page
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