Also keep in mind that some of the gold is dragged out with the dross that is removed on a daily basis when using a "dry" wave solder pot. I have experience with oil covered wave solder pots and they do indeed exhibit a build up of gold, primariy because you are not forming dross and hence not removing some contaminants. We typically dumped an oil covered pot every 3 months either due to gold or copper contamination levels. When we changed wave solder machines to a "dry" wave we found we could go years without dumping the solder pot even though what we soldered had not changed. Gordy Seppanen, Process Engineer Military Avionics Honeywell Inc.