Hello coin enthusiasts,
Yes, patina again, but I haven't found the right thread. It's not about cleaning or patinating but keeping it.
I bought a perfectly matching shell for my Liberties. Unfortunately, I practiced a lot more with the coins and now the patina no longer fits. Same to my c/s. My regular coins are getting lighter and lighter. Thankfully it fades very regularly on the heads side, but strangely enough not on the tails. Now I'm working more on the shell and the c/s and it's slowly getting closer again. But the c part is starting to look different from the regular coin...
I also have two backup coins that I have never actually used. Both have darkened considerably, but one more than the other.
It was "natural" patina I have never treated my coins with anything.

Do you have similar problems or hints on how to deal with the issue (or the right thread)? How do you manage your gaff collections to stay in the same condition?

How are you storing the coins? Unused coins shouldn't change much unless they're in something like a leather purse that isn't lined and/or the leather wasn't fully treated correctly.

Also what types of coins? Copper will darken more naturally than silver. Plastic/vinyl coin holders that reduce air exposure can help both.

To expand this topic just a bit, any tips for cleaning copper coins (not to change the patina, but to get off the grime)?

Plastic sleeves sold for coin collectors. They reduce air exposure, so slow oxidation, and are PVC free so they don’t interact with metals in coins.
https://www.amazon.com/dp/B09XWRZ3GB?ref......ap_share

To clean coins without removing patina in recesses, try these polishing cloths. Lay the cloth flat on a hard surface and gently rub the coin on it as if “softening” the coin on sandpaper. The high points will be polished, but the patina in low spots will remain.
Sunshine 5 Polishing Cloths... https://www.amazon.com/dp/B01N4NYU91?ref......ap_share

Thanks for response.
These are English penny copper and silver Walking Liberties. I have a little chest (wooden box) to store them and the changes on the stored ones are not this big. I will keep them in this little plastic sleeves.
But what changes a lot over time is the patina on the coins I use. The patina is fading away. You know the dark patina "stripe" that Liberties usually have on the date? It was never very strong but know it is a little shade between the last to digits. I'm OK with "living" coins, but I don't want to bother about handling them all the same amount of time to keep a matching look. And I worry about why the tailside is not fading away even on all coins (Maybe I unconsciously have favorites).
However I'm looking for a way that makes the patina stay at it is. Not affected by handling.
Don't you have this problem?

Get them looking how you like them, then spray them with clear lacquer.
https://a.co/d/3WDUfIx

Seriously? I wouldn't have thought of that with my coins. Doesn't that affect the feel/touch?
Is it a specific type of lacquer and does the brand matter? The one suggested is not available (in my country?).

I’ve offered what I can. Best of luck.

Well, thanks I will try.

I'd start with soap, water and a soft toothbrush. Test first.
If it's the green grime on copper from a cheap purse, you'll likely have shiny metal underneath when it's removed - not much you can do about that.