Polishing
also: bean polishing
An optional step that buffs residual silverskin off hulled green beans to give a cleaner, more uniform look.
Polishing is a cosmetic finishing step at the dry mill that rubs leftover silverskin off green beans after hulling. A polishing machine tumbles the beans against each other and against an abrasive surface so the thin, clingy membrane (especially in the center cut) flakes away, leaving a smoother, glossier, more uniform bean.
Why it matters: polishing is mostly about appearance and grading. Clean, evenly colored beans look more attractive and can fetch slightly better prices, and some buyers prefer the tidier presentation. It also removes a little of the chaff that would otherwise burn off during roasting.
There is no real flavor benefit, and not all coffee is polished. Over-polishing can heat and abrade the beans, which is a quality risk rather than a help. Most leftover silverskin would come off as chaff in the roaster anyway. Treat polishing as a presentation choice at origin, not a marker of cup quality, which is decided by variety, processing, and freshness.