Etching blades is a quietly satisfying process. You put the thing in some liquid and some bubbles appear; then you wait. Sometimes you take it out and scrub or rinse it and put it back. What you don’t want to do is take a nap (which turns into a full night’s sleep) while you’ve got a blade in the tank.
I don’t know how long it would take to completely disappear a blade; there’s probably not enough acid and eventually the reaction would run down. I did hear a story about a guy who was building a wrought iron hammer and forgot it overnight in a tank of concentrated ferric chloride – when he fished it out the next morning it was crumbly lace, not a hammer any more.
It has a lovely warm analog feel to it. This time, the etch is deep enough that you can feel it with your fingerprints. Normally, I like to do a mirror polish and then just enough of an etch to change the reflectivity, but “it is what it is.”