The urn I had was clean, and never cleaned with abrasives; but Bee or others will benefit from that trick I am sure. The problem is when coffee oils are allowed to bond with mineral deposits; that's what the denture cleaners and other coffee-cleaners dissolve.

A coffee urn boils the water briefly (the "perking" phase) and then goes into a nice keep-warm sort of simmer as long as you let it run, much like a rice cooker (the non-steaming sort).

It didn't become soup in there-- that happened in the crockpot for the Caldo and in a stovetop pan for the Italian Wedding. The urn is for stock, and only stock.

PS when the stock's done of course I can take the top off the urn and let the stock evaporate down to condense it.

~Susan