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MS70 copper over time

If a copper coin has been treated with MS70 and attains a "MS70 look," will the surface of the coin continue to change over time?
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Maybe if they were stored in a Dansco album or left exposed to air, they may change more readily.
It's good to know this type of surface is stable. I'm looking at a coin which may have been treated this way and was wondering if it can be expected to maintain it's look or if it would degrade.
Use it very lightly (if you can find some), otherwise you'll replace the frost with an oily look.
I don't know if acetone will also remove that frost or not - if so, then that may be a better option.
Then of course the purists will tell you to just find one that has not been treated with anything.
But in my case they were low value coins from a large estate that weren't stored properly and had hazed over, and
I personally think these are much more attractive now, even though they are not 'original'.
And I can now spot treated coins in dealers' cases quite readily!
Once a coin is cleaned, it may open it up to the effects of the atmosphere, whereas an uncleaned coin has a stable surface.