Describe how to block sand a repaired and primed area.

Question

What will be an ideal response?

Answer 1

Blocking is a process that levels an area in order to blend in the uneven areas created by the repair process. Following the repair, a technician may have the substrate at the lowest level, the body filler slightly higher than that, and the old finish (though feathered) at the highest surface. Primer filler is added to the area to fill and level these three heights. The technician must then use a sanding block to level or plane off the three different areas. The block should be large enough to bridge the repair area. As the block travels over the high spots, the technician sands the high spots very aggressively, but with little pressure on the low spots, to have little effect on them. As all the high spots get lower, the surface becomes flat. The process is stopped when all the areas are level, or until there is no more primer on the high spots. If the technician sees the substrate showing (“breaking through”), the blocking should be stopped. The surface should be cleaned and evaluated. It may need to have primer filler applied again, and then have the area blocked again.