I don't know what kind of magical coating they used on top of the black-painted iron (or maybe steel?) box that the thing is made of, but I would like it to go away so I can decorate the thing properly. Maybe it's just car wax? Maybe it's something in the paint itself?
I'm hoping for an answer that is less involved than "disassemble the entire thing, sand it and repaint it". Taking it off the wall is a giant pain in the ass.
It's ironic, because the payphone is literally the only thing in the building I want stickers on, and they stick fine to absolutely every other surface.
I think you're going to have to go abrasive, because all of the really good nonstick coatings are things like fluorinated polymers or silicone, or hard oxides. These are all pretty nonreactive, and the solvents that can touch them you don't want to be near.
I would think the only truly informed answer to this would come from someone who worked at Western Electric, so forgive my wild speculation here. If it were me, I would first try just hand-sanding one side to see if just scuffing the paint would be enough to get things to stick. If that didn't work, I'd try just painting right over the existing finish. I wouldn't bother disassembling, just mask off the front or whatever areas you don't want painted.
How did you get the one payphone in all of creation that can't be defaced by a nine year old with a sheet of scratch'n'sniffs?
Seriously. I'm tempted to suggest the following:
1. Place sign on/near phone saying "Please do not place stickers on this device"
2. Wait for shitheads to perform the obvious acts of vandalism, because of course they have access to shit that will stick to anything
3. Cover up their stickers with yours.
Sadly, I suspect the end results would not be entirely satisfactory.
I suggest that you go at some of the flat, shiny bits that protrude beyond their surroundings with some 2000 grit sandpaper wrapped around a block. If it's wrapped around a block, you won't affect the surrounding areas, and 2000 grit is fine enough that it shouldn't make the metal look all scratchy.
If it does end up looking scratchy, go at it with some car polish, then wash with dish soap to get rid of the wax.
Worst case you're out $20 and 15 minutes of your life. Best case you can ploop on a few stickers.
Maybe spritzing with acetone? That may give you enough of a tacky surface. Wash with IPA after though.
Wouldn't bog-standard lager be a cheaper choice?
No. Acetone will dissolve more organic compounds, including acrylics. Hopefully whatever NASA inspired coating is on that phone will be affected enough that the stickers will be able to adhere, although it leaves a residue that IPA can remove. Best advice I have short of ripping it off the wall and throwing it in a sonicator.
Toluene removes silicone with a bit of elbow grease.
Then try kerosene next.
Fight long chains with short chains.
Fine grit sandpaper would theoretically remove whatever coating eventually, but it would take a really long time.
You could look into soda blasting? It would make a mess but that mess would clean up pretty easily.
Try using a magic eraser on the spots you want to apply the stickers.
Seconded. This might work.
Maybe stronger glue would work. Liquid Nails, Gorilla Glue, etc...
Spray the phone with flex seal, once it's dry the textured surface might give stickers a better surface to stick to
Clear spray lacquer might be another potentially-removable idea. That also gives something you could try roughing up a bit without destroying the phone surface, although it'd be interesting to find out if it all cracks and peels off.
From memory you want many light coats and to try not to leave fingerprints. But maybe you can just mask off the plastic bits and surrounding wall and do like 2 coats.
(What the heck is lacquer thinner made out of, which might be another potential cleaning / prep solution that will probably also attack plastics?)
A nice fine coating of hydrofluoric acid will remove that pesky finish.
Not to mention the insides of your lungs.
Get magnetic sheet, cut to sticker size with scissors, stick stickers to magnetic decals, stick to phone.
I checked mine: Magnets stick to the black parts strongly, but the silver parts are much weaker.
Still, I imagine the whole point was to make the stickers less temporary than magnets...
A professional coatings person of my acquaintance says: 1. De-gloss with 150 grit sandpaper. 2. Rinse and dry with water at least, preferably isopropanol / rubbing alcohol to get the dust out. 3. Press sticker hard and long to improve adhesion.