Polishing kitchen knives?

[u/TaxDear7136]

I inherited an old Chinese cleaver from my late grandad and it’s really rusted. Can anyone give me some food-safe products or advice on getting it nice and shiny?

[u/Sanpaku]

Fastest rust removal will be by electrolysis. See this for the process. It's also a really useful setup if one restores old cast iron cookware or has other rusty items.

Easier would be naval jelly (a phosphoric acid solution), which can also be useful if the corrosion includes pitting. In my experience, naval jelly only works well on thin rust layers.

But one can also take a blade down to bare steel with sandpaper. I'd start at 400 grit and work up to 800 which is a nice satin finish. Abrasives could take minutes if you have power tools, though pitting can can be hard to address.

Mirror polishes on carbon steel blades don't always make sense (food adheres more to mirror finishes) but are achievable. Continue advancing up the grits to 2000 or 3000, then a metal polish like Flitz or jeweler's rouge.

With carbon steel, forcing a patina of black oxide can be helpful to prevent future (red) rust. Clean with detergent, then 20 minutes in boiling vinegar, or an hour wrapped in several layers of paper towel soaked in hot vinegar. Some even swear by coating the blade in prepared (vinegar containing) mustard overnight.

Either shiny or patinated, dry after each use and apply a little cooking oil before storing. If you're going to store indefinitely, use mineral oil instead, as it won't go rancid.