Removal of conductive paint from glass

[dexters_lab]

i have a photomultiplier here i'm trying to remove some brown/red conductive paint from and it's proving difficult, what i thought would be a 5 min job isn't.

the pmt is junk, i just want to remove the red paint from the back and the neck to make it more ornamental

so far the most productive method has been to just use a sharp blade to scrape it off but i have also tried:

white spirit, ethanol, petrol, cellulose thinners, IPA, nitromores paint stripper and various other solvents i found but nothing touches it

i do have dichloromethane, but that would probably decompose the plastic plug end and probably detach the blue filter that's bonded to the front. I would also rather not waste that much of my dichloromethane!

any suggestions?

[daqq]

Acethone applied targetedly by a small swab?

[AntiProtonBoy]

Few other things to try:

* Give it the ultrasonic cleaner treatment. It might take a while before the paint will start flaking off.

* Perhaps give it an acetone bath for a good couple of days. Warning, do not allow acetone to make contact with plastic parts! Only immerse the glass bits.

* Bath of potassium hydroxide or sodium hydroxide (aka caustic soda). The former is harder to get but it is much more potent. Warning, highly corrosive, it will destroy aluminium. Turns your nails into soap. Handle with tick rubber gloves and good eye protection.

[Psi]

maybe you need one of these   

[daqq]

* Give it the ultrasonic cleaner treatment. It might take a while before the paint will start flaking off.

Bad bad idea... if nothing else it's a glass tube with delicate bits inside. You'd probably end up with a broken bulb and lots of photomultiplier bits in the cleaner.

[AntiProtonBoy]

Yeah you're probably right, although I would've thought that ultrasonic cleaners work at water/solid interface where cavitations are produced to dislodge material on the surface. Takes a lot of energy to break glass, whose resonant frequency must be close to one of the harmonics of the ultrasound.

maybe you need one of these   

This thing is hypnotic. I want one... for, um, reasons.

[rdl]

...
so far the most productive method has been to just use a sharp blade to scrape it off but i have also tried:

white spirit, ethanol, petrol, cellulose thinners, IPA, nitromores paint stripper and various other solvents i found but nothing touches it
...

Most paint would have be affected, at least a little, by one or more of those.

I wonder if it's actually paint? Maybe it's some kind of glaze or ceramic that's actually heat fused into/onto the glass surface.

[firewalker]

Hydrofluoric acid and/or Piranha solution?

Alexander.

[PartialDischarge]

Hydrofluoric acid and/or Piranha solution?

Alexander.

HF will eat the glass, he needs nitric acid in around 30%-60% concentration.

[Cyberdragon]

This thing is hypnotic. I want one... for, um, reasons.

There are several of these machines available, just look for laser paint stripper.
http://www.cleanlaser.de/wEnglish/produkte/high-power-cl-1000.php

Just don't burn the house down. 

[dexters_lab]

quite a few suggestions there, thanks!

i think i will try some acetone first off, cheap and easily available

[_Andrew_]

Have found in the past when using cellulose thinners to clean of old anti corona lacquer from crt's the thinners were more than happy to start removing the conductive paint as well.

[Alex Eisenhut]

 

[tggzzz]

I dismembered a broken CRT, and found part of it was opaque ceramic, not glass.

FFI, including pictures, see https://entertaininghacks.wordpress.com/2016/03/09/rescuing-a-broken-tektronix-465-crt/

[dexters_lab]

 

yea, the knife blade works ok, it's very very hard though and the rounded edges of the glass make it hard work to get off.

I dismembered a broken CRT, and found part of it was opaque ceramic, not glass.

FFI, including pictures, see https://entertaininghacks.wordpress.com/2016/03/09/rescuing-a-broken-tektronix-465-crt/

it's paint for sure, you can see where i have removed some of it in my picture