[Scoutmaster]

Unfortunately for collectors, it's more than just soap and water:

The process begins when the general cashier sends racks of rolled coins to Holsen, who empties the change into a repurposed silver burnisher.

Along with the coins, the burnisher is filled with water, buckshot to knock the dirt off, and a healthy pour of 20 Mule Team Borax soap. After three hours of swishing the coins around, Holsen uses a metal ice scoop to pour the loot into a perforated roast pan that sifts out the buckshot.

. . . .

[O]nce-rusted copper pennies turn into shimmering bronze coins. Quarters look like sparkling silver bits.

[ClearCase_guy]

I don't quite understand the need for the buckshot. On the one hand, we have lots of little pieces of metal banging into each other. And we think that they will get cleaner if we add lots of little pieces of metal that could bang into the other little pieces of metal?

But I suppose they've found that it works.