Sanding and polishing to optical clear
Eleven grits, three compounds, and the one rule that decides whether you end up with glass or haze.
Polishing resin is not a skill so much as an obedience test. There is one rule, it is very boring, and violating it is the reason ninety percent of people conclude their resin 'won't polish'.
The rule: never skip a grit
Every grit exists to remove the scratch pattern left by the previous one. Jump from 400 to 1500 and the 1500 paper simply polishes the walls of the 400 scratches — you will buff forever and the surface will stay hazy, because the scratches are still there, just shiny.
The progression
- 80–120: shape only, if there's a real defect
- 240–400: flatten
- 600–800: remove the flattening scratches
- 1000–1500: the surface starts to gloss slightly when wet
- 2000–3000: it should look nearly finished while wet
Then three compounds
Cut, refine, finish — automotive compounds, because clear coat is chemically very close to cured epoxy. Foam pad on a drill backing plate, under 1500 rpm, and keep the pad moving. Heat is the enemy: too long in one spot and you will burn a cloudy patch into the surface that has to be sanded back out.
Wet-sand wherever possible
It eliminates the dust entirely, it keeps the paper from clogging, and it cuts faster. A spray bottle and a bucket is the whole setup.
Put it into practice
Everything in this article, on one bench.
Our starter benches ship with enough material for two attempts and a printed pour card — so the technique above has somewhere to land.