Steel Espresso

Steel Espresso

How to clean in an Italian cafe / espresso pot?

This is the kind I'm talking about: http://www.gwdoling.co.uk/img/ih/kcraft/31906.jpg of bottom where you put water with white bark all fields, although used filtered water rather than tap water. How can to scrape or dissolution of such a distance? I really can not reach there with steel wave, dish brushes and do not provide sufficient friction to be effective. Does anyone has experience with this? Please do not advise something what you (or someone you know) have not been tried and found effective. This is not a "machine." View photo link for clarification.

Soak in some white vinegar, then rinse well ..=)