On your web site you recommend Cleancaf for descaling the Classic. You even have a video that uses Cleancaf on the Classic. Yet in the product description for Cleancaf, your web site says NOT to use Cleancaf on aluminum boilers. But the Classic does have an aluminum boiler. In that case, it seems that Cleancaf should not be used to descale the Classic?
Not answering your question directly, but I have been using the Durgol Swiss Espresso descaler very successfully in my wife's Gaggia Classic. It cleans quickly and rinses out easily. Absolutely no after taste. I clean the shower separately with a painters brush and mild detergent using light swirling motion. The shower needs to be cleaned much more frequently than the machine. It seems the the shower needs cleaning every 40 shots or so, whereas the machine will depend on your water condition; I get several hundred shots before decaling.12-05-13 05:25PM
At some point within the last year, Urnex reformulated Cleancaf in such a way as to not make it entirely suitable for machines like the Classic. I second Daniel's suggestion fo Durgol Swiss Espresso Descaler, as it's designed explicitly for this type of use and is aluminum safe.12-18-13 07:18PM