Why Are My Morgans Toning?

I don't know how PCGS cleaned up my coin, they do not disclose their methods. My "methods" are that acetone typically results in similar results. I wasn't about to mess with this PCGS coin since it developed spots while in their holder and it is a high value coin. I have seen residue redeposit right in front if my eyes when acetone evaporates and is not rinsed.

You've seen residue deposit... did you test your acetone to make sure it was pure acetone first?

Your acetone was probably contaminated somehow, that simple.

Yeah, don't do that in the future. Dip, hot water, distilled water, acetone. That's all ya need. I've used this method and probably had an upwards of 200 coins slabbed problem-free afterwards.

1 gallon of acetone...you must do a lot of soaking!

Back in the 1970s us "kids" used benzene. No gloves either. Well, after I got my chemical engineering degree in the 1980s if you don't want to wear gloves, acetone is the way to go!(plus it is harder to find benzene these days) If you are using soap, I suggest Dawn and always distilled water. No time to get into specifics.

Be sure to use the squished peas, they are less harsh than the applesauce baby food. And Gerber is the best, I remember that from over 50 years ago.

And as Conder101 stated, Whatever was dissolved in the Acetone will just be redeposited right back on the coin. Whatever Acetone captures just doesn't vanish, it's now in the Acetone and as that evaporates, The STUFF is now left. It's just common CENTS you know. Rinsing with distilled water helps get rid of that STUFF.
As to dish soaps and just wash off. This has been explained many times before. No two dish soaps are the same. Some may contain acidic properties and some may contain almost anything. The formula used by manufacturers is proprietary and in most instants not easily found out. The Dish Soap you use today may be completely different than tomorrow also. It could do more damage than good to a coin. Dish Soaps are not made to clean coins, just dishes. And remember that even todays so called Silver ware is mostly Stainless Steel, not Silver so not much of a problem for Dish Soap.
And removing it with almost any kind of tap water is just as dangerous. Tap water everywhere is either full of Chlorine, Fluorine, Salts from water softeners, Iron or Lead from pipes, etc.
You really just don't know what is in what so play it safe.
And if you are having problems with house plants dying and your using tap water, could well be it is run through a water softener which leaves salts in the dirt. And that kills plants.

I think there was a misunderstanding about the pure acetone leaving deposits debate. Distilled water wouldn't really leave any deposits, but if you soak a salt covered item in it, the salt will be dissolved. As the water dries that salt will re-deposit on any surface it touches.