When acid washing, you must protect the parts you don't want changed. I use plain fingernail polish (black since it's easy to see). Detents, pivot holes. Any threaded holes in liners and frames must be protected from the acid. Acid etching, basically is 'eating away' parts of the metal. Holes in the steel become larger, threads inside holes will be eaten away or reduced. Bearing and bushing surfaces will be roughed up and no longer smooth. All of these tight tolerances are affected by the acid removing some of the steel. Lock mating surfaces for liner locks, frame locks, and lockbacks. All need to be protected from the acid. Protect the edge with fingernail polish as well and if just acid washing, once finished, clean the polish off with acetone, and touch the edge up.
When acid washing, I thouroughly degrease all parts (dishwashing liquid and hot water works great), dry well (a hair drier works great here and again, you don't touch the balde), then put on rubber gloves and clean all parts to be acid washed with acetone. oil from your fingers and hands can leave a splotchy finish since they counteract the acid etching process.
Once done with the acid wash, clean all the polish off with the acetone. Lube appropriately during reassembly, then touch up the edge. If' you're stonewashing after the acid wash, leave the fingernail polish on. It will protect the same surfaces from getting roughed up. Once complete, clean the stone wash media and liquid off, touch up the edge and enjoy.
