Block Sand The Right Way IP
Block sanding happens at two stages of the vehicle painting or restoration process.
1.     During the repair process of metal, plastic, SMC, and fiberglass
2.     During the refinishing process of sanding primer surfacers or color
Block sanding during the repair process is when you restore the damaged part to its original condition. Once the damaged substrate is straightened, a rough feather edge needs to be applied to the surrounding coating. This ensures that the layers of the coating that have been damaged are as level as possible.
Block sanding during the refinishing process typically involves smoothing out a primer surfacer for slight imperfections in the topcoat.
Things to consider when block sanding:
For both stages of block sanding, we recommend that you never skip more than 100 points with sand paper. Once you get to P400 grit you can jump to 600 or even 800, but until then make smaller jumps up in grit to guarantee you are removing all imperfections.
When you choose to color sand try to minimize the size of the area that needs sanded. You don’t want to put aggressive and unwanted scratches in your finish. When dry sanding, use a soft pad with minimal pressure – let the sand paper do the work. If you are wet sanding, make sure to soak your sandpaper in clean water with soap in it for lubricant.
Evaluate the size and shape of the area prior to starting. Blocks come in many sizes and often times the largest option will be the best, but you have to be careful. Large blocks can leave large scratches beyond the repair area.
  • Use a flat block on flat panels and try to stick to a 45° motion in relation to the panel. This will provide a straight repair both horizontally and vertically.
  • Use round blocks in rounded contours and style lines. Continue to stick with the 45° motion to prevent the block cutting into the surface.

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