Oh, thank you -- I meant to do that with the image and just forgot.  

No, I don't think the keys are discolored at all; they just have a bit of mold that looks uninvitingly toxic to me. Lysol sounds like a good place to start. 

Relax, Folks. That material is almost certainly not a living mold or fungus. The plastic that Royal used to use for its keys and lever tips and platen knobs, etc. often exudes something from out of the plastic itself, just some chemical that isn't so stable as they though when they made the thing. It might be toxic but not in the same way a mold is.

I haven't found a chemical that gets rid of it, so my tool of choice is a sharpened wood stick, maybe a popsicle stick carved to fit the curve of the keys or whatever. A toothpick for tiny crevices. Wood doesn't scratch the plastic. Maybe plastic scrubbers will work, too. Steel wool will scratch and leave a dull appearance and maybe remove printed labels.I do believe in sanitizing keys and use alchohol for that and think all those other things mentioned here will also do fine. It's just that to get the stuff off, I have to scrape. Then I wax the pieces for a good shine. Feels good, too.

Mold is a genuine problem on fabrics, leather, felt soundproofing, wood, and other organic materials, just not on these plastics nor metals. Maybe some kinds of paint, too, though I don't think I have seen that. Treat those molds with disinfectants, vinegar, Fabreeze, and so on.

HTH. Have Fun!

Agreed, Uwe. Thanks for adding that detail. You're right that keys have more on them than just plastic. Note that that is why I also disinfect the keys and other parts. In fact, that's my first move and invariably the disinfectant does not remove much of the white material---it does not comes off easily with a wipe. It does come off pretty easily with scraping with a softish tool so I just plan on doing that rather than keep on searching for yet another chemical. (Any chemists out there who can suggest an easier treatment for this exudate, this degeneration?)

The main point of my post was to counter the careless assumption that the stuff is mold and that it should respond to anti-mold treatments. Words mean something---or they should, if they are to be useful---and to call one thing by the name of something radically different is to mislead readers about what approach to take.

Whenever the subject of mold on keytops comes up, the degenerating plastic explanation should also come up. Ever wonder why this is so much more prevalent on Royal typewriters? Different plastic formulation from other manufacturers?

Last edited by M. Höhne (15-7-2014 08:04:36)

M. Höhne wrote:

Whenever the subject of mold on keytops comes up, the degenerating plastic explanation should also come up.

You're absolutely right. 

M. Höhne wrote:

Ever wonder why this is so much more prevalent on Royal typewriters? Different plastic formulation from other manufacturers?

I've actually encountered very few, less than a handful of typewriters with the degenerating plastic issue with respect to keys, and none of the 15 or so Royal models I have had the issue. Granted, many of those models predate the use of plastic keys, but it still leads me to wonder if the keys (and the plastic used for them) were sourced locally? The reason I mention this is that of the plastic key models I have from that manufacturer, most were made in Canada, and in some cases the Netherlands.

That's not to say I haven't encountered manufacturer-specific issues with other materials. For example, of the 10+ Consul machines I own, the majority of them used what I describe as sub-standard rubber, especially the ultra-compacts which inevitably required me custom fabricating new rubber parts for them.