Electropolishing smooths a metal surface electrochemically. The part is made the anode in a bath, and controlled current dissolves a very thin layer of metal from the peaks of the surface. The result is smoother than mechanical polishing can typically achieve at a microscopic level.

In drinkware it is usually applied to the inner steel surface. The smoother, more level surface is easier to clean and offers fewer microscopic crevices where residue or bacteria could cling. This is a meaningful step for the drink-contact side.

Electropolishing also improves corrosion resistance beyond mechanical polishing, because it removes stressed surface metal and leaves a more uniform, passive-friendly surface. It is often paired with passivation for the best result.

Practical takeaway: For food-contact interiors, ask whether the inner wall is electropolished and passivated, since the two steps together drive cleanliness and corrosion resistance.