This weekend I had a chance to visit my friend Reed on his farm about an hour's drive from here. Reed has been everything from an advertising art director to a publisher to a woodworker. Before I started my present job at Fernbank Science Center, Reed and I built some cabinetry and furniture projects together, and we also built and operated a solar lumberkiln for several years.
Of course we read what we could about it before we plunged in and built the kiln, but even so we had quite a learning curve. If you're interested in learning about this, do a Google search for Eugene Wengert of Virginia Tech (though I understand he moved to Wisconsin in his retirement). To our surprise, every load we put in there ended up as mostly useable lumber that we got quite cheap compared to retail dealers. We also got some pretty meaningful and unusual wood, from trees that had personal meaning to our clients. Eventually we offered some wood for sale, though when you have the whole log for sale it's hard to know how to keep folks from buying all the wide, clear boards at a price that makes up for all the narrow, knotty boards you're left with. So with this go-round, we'll be segregating and pricing the boards by grade.
Another aspect of operating the kiln has to do with the glazing material. You always read about various plastic roofing products which are supposed to do the trick, but in our experience they burn out in 3 or 4 years. I guess that since most of the kilns you read about seem to be in northern states, the heat they're subject to isn't quite as intense. Here in Georgia, it's pretty typical for the kiln to reach 160 degrees Fahrenheit on a sunny July day. The heat is simply too much, and the plastic glazing gets cloudy, then brittle, and finally just crumbles away, leaving the innards of the kiln open to the elements. Having re-glazed it three times with three different products (twice with corrugated sheet products from home centers, and once with a rolled sheet material designed for greenhouses and guaranteed to stand up to high temperatures), I have decided that the next re-glazing will be with glass.
Part of what I was doing this weekend was measuring the roof as it is now, to give me some idea of how much glass I'm going to need. I have several possible sources in mind, but my favorite possibility is a construction salvage yard here in Atlanta which sometimes has large pieces of architectural glass available. That seems best to me - - just a few large sheets. But we'll see how things go. No doubt I'm completely oblivious to some safety hazard or some property of the material that needs to be taken into account. Still, I think I'll forge ahead and see what we learn this time around. I'll keep you posted.