Hello Everyone. Spring is right around the corner, the sun is getting higher and the daylight is lasting a little longer. I am looking forward to longer days at the mill and opening up logs to create more inventory for the website. Part of this task is drying all the different walnut slabs that I saw.
Immediately after a slab is taken off the log it is stacked and stickered. The stickers are 1 inch by 1 inch to allow airflow between the slabs. The slabs are also stacked consecutively as they are sawn so I can keep the book matched slabs together for inventory purposes. After stacking, the sawn logs are moved to various shelters around the mill for air drying. The logs will remain there and monitored until around 20% moisture content. Depending on space and solar kiln schedules, some logs may be moved into one of the solar kilns when average moisture content is 25 to 30%. All of this is done to prevent degrading the wood due to the introduction of artificial heat and to rapid moisture removal.
The dehumidification kiln is used in the last step to finish drying and heat treat the slabs. Once the slabs are at 20% moisture content or below, the chances of degrading the wood is drastically reduced. The kiln load will be brought up to temperature, usually 100 degrees to start. The dehumidifier will then be turned on to remove moisture from heated air. This is all done at rates to keep the removal even. You don't want to remove moisture too quickly because it can degrade the exterior of the slab and trap moisture in the interior. I monitor the water output and check moisture content daily.
Once the moisture content readings are below 8 percent throughout the kiln, I turn off the dehumidifier and turn the temperature up to 140 to 150 degrees. This is referred to as the sterilization cycle. Wood needs to reach an internal temperature of 135 degrees maintained for at least 48 hours to kill any bugs that may be inside.
This is a summary of how I dry walnut to be able to keep producing quality live edge slabs with great color for the customer. There is a ton of science and experience that goes into drying wood correctly ... and a little luck too.
Thank you all for joining along and all the support. As always, feel free to reach out if you have any questions or need help with anything.
Here is a short video explaining part of the Dehumidification Kiln process.