WARNING****Galvinized metal is coated with zinc which will volatize at relatively low temperature and could condense on food *** Should be aware of zinc toxicity
That's a good point - I'd like to know at what temperature it does become toxic. My understanding is that while the temperature in which the zinc coating becomes toxic, while relatively low, is in the neighborhood of 700 degrees farenheit.
In this particular setup the hottest it ever gets inside is 250 degrees (note the temperature gauge on the top), with a maintained temperature of 200-225 degrees. The food sits in the chamber on stainless-steel racks and is never in contact with the can. The heating element is a propane camp stove, and its flame is never in contact with anything other than a cast-iron box containing wood chips.
Take Charlie's concern VERY seriously, folks, and do be very careful if you choose a setup like this. Clearly the galvanized can should not be exposed to excessive heat of any kind.