Knurling builds the callus. The callus ends the set.

Keep the callus. Lose the edge.

Lifters do not want soft hands. A flat, even callus is what lets you pull a heavy bar without the knurling eating skin. The problem is a callus that keeps growing: it rises above the palm, catches on the bar as it rotates in the hand, and either pinches or peels. Kettlebells are the worst, because the handle spins through the grip on every swing and snatch.

The routine is simple. File the high spots down to level every few days. Keep palms dry so the bar slides instead of dragging. Put water back into the skin at night so it bends instead of cracking. Rhino's hand file and sweat control came from climbing. Lifters adopted both.