I've only very recently been calling the typewriter cleaning process I use "The Magic Margin Treatment." It sounds much more grandiose than it actually is. The process only requires some simple equipment and the best paint polish/cleaner in the world.
This process is only for shiny painted typewriters. I would not use it for wrinkle paint. In fact, I have a whole other process that I follow for cleaning textured paint typewriters. I'll share that one with you later. To polish grandmother's old Model O you will need:
Meguiar's Cleaner Wax (Target), microfiber rags (Target), and a shiny painted Royal Model O (wherever you find one). My mother-in-law (the most accomplished stain remover in the world) would always suggest you start with water. It is "the best solvent." Not sopping wet, mind you, just get off the major dust and other caked on crud with a wrung-out rag. This particular Royal was very clean when I got it, but even with a very clean gloss paint typewriter there is hidden dirt. I like to use 2 different colored rags to ensure they are used for their respective jobs; cleaning and buffing. I'm going to use the one with a touch of grey for cleaning.
Don't use too much. Just a dab will do you. Spread a thin layer onto the typewriter and work it in with a circular motion. Let the polish dry to a slight haze.
I tend to work in sections to ensure that everything is done well. Is it working? Well, if you look at the rag where you applied the polish you will see this sign that your typewriter is getting cleaner:
Yes, that is 80 years of dirt, smoke, and crud. Keep in mind that this machine was pretty clean to start with. It's just a fact that most typewriters 50 years or older were in houses or workplaces where people smoked. That grime is really long-lived and gross. You always feel better after it's gone. The funny thing is that often the gloss black typewriters don't look too dirty.
Buff with the second cloth and there you go. After you are done, there should be a noticeable mirror-like difference.
|<- Unpolished. Polished ->|
The bottle of Meguiar's says you should not get this on rubber. I would agree. It stained the platen of the Ambassador and it nearly impossible to remove that residue. Caution would be in order. This particular cleaner does not polish metal. For that I use Mother's Mag and Aluminum. You can try, but it might be a waste of time. Polishing is a great therapy.
So, feel confident in getting that old gloss black (or any other color) typewriter clean and shiny.