3M Wetordry sandpaper cuts fast and smooth, and it can also be used to repair surface defects. It can be used with water or cutting oil. Ideal for sanding metal for repainting or prior to primer coat.
3M 09086, Wetordry Sanding Sheets 9086DC-NA, 9 in x 11 in, 320 grit, 7010340941, 5 sheets per pack
$3.17
Factory Stock, 7-10 Day Leadtime, Priced Per Pack
3M Wetordry allows you to sand between coats of varnish and paint or other finishes. Can be used with water to reduce clogging and extend abrasive life. Ideal for sanding metal for repainting or prior to primer coat.

Dynabrade 51811 .1 hp Straight-Line Pencil Grinder, Rear Exhaust, 1000,000 RPM, 1/16" Collet
Dynabrade 53533 Cone or Plug Grinder (Triple Extension)
Standard Abrasives 709700, A/O Straight Cartridge Roll, 1/4 in x 1-1/2 in x 1/8 in 320, 7100080013
3M 19768, Utility Cloth Sheet 314D, 9 in x 11 in P180 J-weight, 7000000356 
