When companies don’t ship their lenses with the part number etched on the side, I have to write it in myself. But sharpie fades after just a couple of years.
Is there something more permanent than sharpie? particularly for handwriting on frosted glass?
My wife's a museum conservator. She uses "micro-pigment pens", which don't fade, for writing IDs that must never be lost on artefacts.
Apparently they're widely available, even at Michaels'.
She says yes, that's them.
Another tip from her: if you find something that they don't want to write on, like the ink/pigment doesn't stick, put down a layer of clear nail polish first and let it dry, then write on that.
And with or without that base layer, if you want to make doubly-triply-extra-sure that nothing will accidentally take the markings off, put another layer of polish on top of what you've written, after giving that time to dry.
Janelle Shane
C.