Can ink stay permanently on metallic coin surfaces? [solved]

Just something I was wondering, because a few months back I added this French Indochina essai coin:
https://en.numista.com/catalogue/pieces114983.html

As you can see, the coin page's comment section says: With ink weight notation as applied at the mint.
I was wondering if ink can really remain permanently on coin surfaces? I also see some coins with ink defacement, like this one I found while browsing the France - Feudal sections:

https://en.numista.com/catalogue/pieces54138.html
I tracked down the pictured coin's cgb.fr page, and it says nothing about the number.

I think there is a solvent for every kind of ink. There is no way ink can soak in to a meal surface, so it will come right off, just like tarnish will, given the right solvent, and a little effort.

Unfortunatelly researches on numismatics and collectors especially in the 19th century often applied ink onto their coins.
Is this piece you showed really a pattern strike, I'm surprised.

Ink can stay very long, Japan for example has gold coins with applied ink on them.
See here for example
https://coinweek.com/world-coins/japanese-coins/a-world-of-gold-coins-japanese-gold-oban/

Quote: "Mr. Midnight"​I think there is a solvent for every kind of ink. There is no way ink can soak in to a meal surface, so it will come right off, just like tarnish will, given the right solvent, and a little effort.

​Yeah, that's exactly what I thought!

@Idolenz
Thanks for bringing those up, I completely forgot about them.

Yes that coin is indeed an essai, it is listed in Lecompte, and I remember it was actually on a Stacks Bowers page shown to me by a team member who noticed it wasn't already added. Too lazy to go dig it out in my inbox at the moment though....

I also know that not just numismatists, but also archaeologists and paleontologists back in the day (sometimes even today I think) used to make ink notations on their finds as well, so there's that. Mind-boggling to think of now that they'd even seriously consider doing such a thing.

Slightly off the original topic, but why would the coin/pattern be severed like it is? Was it to insure the pattern was never placed in circulation? Or as part of the testing process?

Quote: "worth"​Slightly off the original topic, but why would the coin/pattern be severed like it is? Was it to insure the pattern was never placed in circulation? Or as part of the testing process?

​It was probably the latter, since the (new) weight is noted down in ink on the coin.

Some time ago I bought (win) a lot of old Chinese Northern Song Dynasty cash coins. When I got them I realized that some of them had a catalogue number written on the wide outer rim of the coin. All those coins had "Chinese" type of tags attached with twine, so what is/was the purpose of the inked catalogue number? I can tell you that it was not easy to remove that ink without harming the coin itself.

Quote: "Ollisaarinen"​Some time ago I bought (win) a lot of old Chinese Northern Song Dynasty cash coins. When I got them I realized that some of them had a catalogue number written on the wide outer rim of the coin. All those coins had "Chinese" type of tags attached with twine, so what is/was the purpose of the inked catalogue number? I can tell you that it was not easy to remove that ink without harming the coin itself.

​Sometimes you can find coins that have ink inventory numbers that were applied by museums long ago.