Eric Strasen
Forum Participant

The product is Etchall. It is not dilute hydrofluoric acid as I earlier thought, but ammonium bifluoride. In any event, the user is supposed to wear latex or rubber gloves, safety goggles and “protective clothing” (almost sounds like they want you to put on a haz-mat suit).
I didn’t go beyond the latex gloves.
It comes in several different formats. I chose the liquid as I used it for frosting pilot lamps. Just pour it in a small plastic tub — a tub meant for denture cleaning/storage works great, as long as you don’t plan on parking your teeth in it — and put your pilot lamps in it for 15 minutes. It does not affect the metal base of the lamp, just the glass.
Etchall also comes in a cream, which is what you would want to frost the glass on a vacuum tube.
It is available direct from the manufacturer — https://www.etchall.com — and from eBay. Price appears to be the same either way.
The liquid comes in a 4-ounce bottle. I didn’t search the site long enough to determine if it is available in larger sizes.
The stuff may be used repeated times.
Hope this was helpful.
Eric S.