How To Block Sand Primer Surfacer

1. Apply Guide Coat To Primer
2. Using a block, cross sand the primer using 220 grit sandpaper. (if you know for sure that it will notneed to be blocked a second time you can start out using 320 grit sandpaper.)
3. Sand until all guide coat is sanded off, but stop sanding when you sand through to the metal or body filler.  Try to keep these break through areas to a minimum.
4. If the primer blocks out good, final sand the primer with 400 to 600 grit sandpaper.  If not, repeat this process.

Now you’re ready to clean, mask and prepare for paint.