Why Is This The Worst Beer Cup My wife bought me a special cup for me to drink beer out of.  The problem is that, if I pour any beer in it, it goes crazy with foam.  I will get just a few ounces of beer in there and the rest of the 16 ounce cup will be full of foam.  The cup is hand spun from clay.  The texture is still pretty rough.  So, if there is any glazing, it is not really noticeable.  The cup also has little brown specks in it here and there.  Does anyone know the reaction that is taking place to produce all this foam?  Is there a way to fix it?  Let me know if I need to supply any more details.  You should assume you are talking to someone whose last chemistry class was high school.
The rough texture is a physical catalyst (provides nucleation sites) for the evolution of carbon dioxide from dissolved carbonic acid. Pottery glaze fixes the foaming issue.