screens are just a defense used (usually) for protecting your throat from hot ash flyin in that STINGS!!! i only use screens on metal pipes, never used one on a bong or bubbler though =\ fumes arnt a worry they are designed to be heated intensly and usually brass or steel, dont use aluminum or tin...that shit can give you brain tumors and all sorts of shit =X best way to eliminate that taste is to find a screen that some old buddy used for awhile, burn the resin off and use that, all the taste is usually burnt out after a dozen or so bowls