ANy build should be allowed to burn off the zinc before you ise it. Zinc Flu is no fun, keep your head and face away from the whispy gray fumes and let the zinc burn completely off on super dooper blow torch high so that you dont have a contamination issue later on. Zinc can be removed succesfully, but attention must be paid to insure it is all completely burned off prior to exposing your brew to zinc fumes. Take it from an old skool welder with COPD, dont take chances. It is much nicer to be able to breathe without struggling due to being young and stupid a long time ago. Just sayin,, be carefull with zinc and you will be just fine, but ya gotta eliminate it safely and completely to avoid issues later on.... Nuff said......
Wheelchair Bob
Wheelchair Bob