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Message:: [QUOTE="SuperDave, post: 2298256, member: 1892"]The thing you need to know about dipping is, it physically strips a layer of metal off of the coin, never to return. That's how dip removes toning - it removes it. One can only remove so much metal - so many layers of molecules - before the coin no longer has the microscopic roughness which causes "luster." Such a coin is referred to as "overdipped," and once you've seen one you'll know forever what they look like. They look destroyed, because they are. Lifeless. The detail is there, the coin is obviously Mint State, but has the dull finish of an EF-AU50. And here's the kicker: the damage is cumulative over the life of the coin, and no two coins are the same. Strikes differ, planchets differ, and two identical coins will differ in the total immersion time in dip they will tolerate before being ruined forever. And you will not know that limit has been reached - there is no prior sign - until you've killed the coin. I therefore cannot offer a hard number regarding how long you can dip a given coin. I_can_say that you'll be very lucky if it exceeds ten seconds' total immersion in full-strength thiourea (diluting it gives you more time, but not in linear fashion, and it slows the production of results). The trouble is, you cannot ever know how much of that has been used up by a previous owner. That's why dipping is a crapshoot.[/QUOTE]