Solar Kiln Information


Our trailer-mounted solar kiln was built in 1995 as a demonstration unit to provide first-hand experience drying a variety of wood species in different parts of Oregon - from the high desert to coastal rainforests.

By late 2007, time had taken its toll on the kiln - all of the plexiglas panels were broken (one large section was missing), some of the wood was rotting, one of the fans was damaged, and the kiln was long overdue for a paint job. The kiln was put back into shape in February and March of 2008 thanks to a dedicated team of volunteers*.

*The kiln renovation team included: Master Woodland Managers Lester and Robert Helmig, Scott Russell, Doug Shannon, Loren Bowman, and Monte Waldorf; OSU Extension Forester Mike Bondi; Kevin Kaster, Kaster's Kustom Cutting; and Ken Cushman, Oregon Department of Forestry.

We will update the table below as the kiln travels around Oregon.

Date kiln was loaded Location Species, dimensions, total volume MC before drying Date kiln unloaded MC during and after drying Notes
6/10/97 Klamath Falls western juniper, 5/4 x random width, 450 BF Green 6/29/97 20-25% on 6/16; 8-10% on 6/29 Minimal end and surface checking; substantial warp (bow and crook) due to inadequate top weight; weather was clear w/ temps. in the 70's-80's; inside temp. and humidity not recorded.
3/24/08 Oregon City western redcedar, 1x6, 8-14', 475 BF Green (air-dried 3-4 weeks before loading) 5/2/08 7-15% on 4/16; 6% on 5/2 Boards look good - no obvious checking or warp; weather has been quite variable - cloudy, rainy, and unseasonably cool for first two weeks; sunny and very warm (high near 80) on April 12 ; temperature and humidity data (graphs - 3/24-3/28, 3/29-4/16) show temps inside varying from 34 to 154° F (outside temp 30-80° F), humidity varying from 10-100%
5/9/08 Aurora 2/3 English walnut; 1/3 black walnut, 8/4x24" (large slabs), 8', 320 BF Green 8/20/08 30% on 6/2; 15-20% on 6/18; 8% on 8/20 Boards loaded into kiln on same day they were sawn; sunny and 70° on day loaded; weather cool and rainy through May, hot and sunny in June (graphs - 5/9-5/27, 5/27-8/20); slight end-checking visible on 6/2. Overall final quality good.
Summer 2008 Aurora western juniper limbs       Several batches of limbs have been dried. Drying takes just 5 days and quality is very good (no temp/humidity graphs available due to datalogger failure).
Fall 2008 Aurora mixture - 8/4 redwood burls, 12/4 walnut slabs, 6/4 myrtlewood, 5/4 walnut boards Green   7-10% on 4/16/09 Note: temp/humidity meter quit working
Spring 2011: Kiln is not in operation due to high energy costs (electricity for fans) for firm using the kiln - costs were acceptable for softwoods but too high for slower-drying hardwoods; other challenges include time involved in hand loading the kiln and to monitor kiln in summer (a load of walnut was ruined on a hot day!)
January 2015:  Well, after a good 20-year run, our solar kiln is now 'decommissioned.'  It was dismantled and the trailer has been repurposed for the transport of a lumber tension testing machine.