Starting in 1938, San Francisco's Westin St. Francis Hotel began washing all of the change that flowed through the business. Hotelier Dan London initiated the process to prevent grimy coins from dirtying the fancy white gloves worn by women visiting the establishment. These days, the responsibility belongs to one Rob Holsen. From a 2010 SFGATE article:
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, bird shot 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 bird shot.
The wet coins are then spread out on a table beneath heat lamps.
This is where once-rusted copper pennies turn into shimmering bronze coins. Quarters look like sparkling silver bits. It's also where Holsen gives the money a quick quality inspection…
Once he's satisfied, he feeds the polished money into a counter, which shoots the change into paper rolls to be distributed to the hotel's cash registers.