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I have been picking up 4 boxes of pennies from a certain branch for a bit now and the pennies are always really dirty..Theres gunk and sludge on almost every one or just dirty... Whats the best way to just get the gunk off the pennies without ruining any of the value?

Acetone.

You should note that cleaning coins will negatively effect the numismatic value but won't effect the bullion value. I generally dont bother but have considered cleaning the green slime coins as opposed to quarantining them.

Any good tumbler will do the trick. Tumble coins with a little soap to remove surface gunk, rinse, then dry thoroughly and then dry again. Did I mention to make sure the coins are dry before storing? A small desiccant pack in your airtight container of choice will keep your now clean coins from catching almost any kind of coin cancer once this is done. I keep mine in a safe, loose in boxes and bags, with a 20 watt heat stick to keep everything dry and comfortable for all my little metal friends. Please note that this should be for bullion only. Numismatic value can be severely diminished by cleaning coins using this method.

One branch of my main bank had a customer bringing in rolls and rolls of wishing well/fountain coins. Yuck. I mean verbage much stronger, but you get my drift. Simply nasty stuff and a good bit of it copper. It's back in the wild getting the pocket tumbler treatment. Thankfully that run of coins has run out, I hope.

So what do you guys think i should do in my case with the pennies looking how they are? I dont wanna ruin the numismatic value

well if your boxes are all dates like THAT I wouldnt worry about it...

This topic has been banged around before, search on cleaning pennies. Those two don't look to bad, I've got almost a gallon now, of dirties, I'm keeping separate. I need something myself. I experimented with unsweetened cranberry juice, wow did it work, to good, the list is long on what will clean a penny.

I have about half a CTU of uglies that I just hand pick out of the copper side when running. Im gonna wait until I have a full CTU then try to sell them on here as ugly copper for a discount. Rather than invest in the tumbler and all that.