Hi Ryefarmer,
The best copper to use for a still is alloy 122, Also known as alloy C12200 deoxiginated high phosphorus. Never use alloy C110 electrolytic tough pitch copper or Alloy 103 oxygen free copper. There are several small still manufacturers that don't know any better and they use alloy C110 because it is the easiest to get. If you would like someone to do the design work and engineering on your still, just let me know. We can give you a really good price on that. If you would like to know were to get the alloy C12200 copper let me know and I can help you with that as well. paul@distillery-equipment.com http://distillery-equipment.comhttp://moonshine-still.co