I've found a big Sharpie is pretty good for marking ingots. Just got a box each of WW and PB ingots, can tell the difference by rattling the box and listening but that's even less scientific than the pencil test.
Life Member NRA, TSRA
Smokeless powder is a passing fad! -Steve Garbe
I hate rude behavior in a man. I won't tolerate it. -Woodrow F. Call Lonesome Dove
My favorite recipes start out with a handful of used wheelweights.