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Home Priming Block Sanding

Block Sanding

Apply your primer surfacer in thinner coats to allow solvents to flash between coats. Remember, you may apply primer surfacer as many times as you like. Professionals will apply, block sand and reapply 3 times before they are done. After putting 3 to 4 coats of a 2K primer surfacer down,


Apply a guide coat

Using either a cheap spray can of a different color primer or 3M guide coat. This will allow you to see your low spots as you sand. Using a cross hatch pattern, sand the first coats with 80 to 180 grit based on how good your body work and primer work is. You should be using hard, flat sanding blocks like Dura-Blocks or Soft Sanders on curved surfaces. These will help you get it straighter.

Apply a couple more coats of primer

Your next couple of coats should not need to be as heavy as you first. You should now be filling the smaller low spots and 80 to 180 grit sand scratches. We now will be putting on more guide coat and switching to 240 to 320 grit paper, still on Dura-Block.

SEM-Guide Coat Black Aerosol SEM-Guide Coat Black Aerosol
3M Dry Guide Coat, 05861, 50 gr Cartridge and Applicator Kit 3M Dry Guide Coat, 05861, 50 gr Cartridge and Applicator Kit

One last time

More primer in thinner coats. Remember we are now filling 180 scratches. You can now finish block sanding with 400 girt on a board. Then follow up dry sanding with 500 to 600 grit on a D.A. or wet sanding with 500-600 by hand.

Your primer sealer and paint will fill these smaller scratches. Don't use any finer paper because this is the right size of bite for our mechanical adhesion to the paint.

Check out our wet and dry sanding areas under our buffing catagory for more information.

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