Vacuum Kiln Drying Process & Moisture Testing Explainer

The vacuum kiln is a very important part of the process. It allows me to do thicker wood properly. In my opinion, dehumidification kilns are good up to about 1½ inches. Standard steam kilns do 2 inches, but on a long schedule. Most woods that I process — with the exception of hickory, walnut, and white oak — are in here for about 4 to 5 days per inch of thickness. Right now, I've got 2-inch white oak in here on the second half of its drying schedule. Inside the vacuum vessel, the wood is heated while under vacuum pressure. This pulls the moisture out much gentler than any other form of kiln drying, preventing internal stress, honeycomb splitting, and color degradation.