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WPE 2018 Dry Kiln Short Course

The 49th Annual Dry Kiln Operator’s Short Course was held at Hodges Laboratory by NC State’s Wood Products Extension from June 5-8. The program had 24 participants and included instruction by NC State’s Phil Mitchell, Frederik Laleicke, Guillermo Velarde, University of Kentucky’s Terry Conners, and guest lectures by Dan Mathews (SII Dry Kilns), Mike Sanders (USNR), and Niels Jorgensen ( The program also included site visits to Edwards Wood Products Sawmill and Kiln Plant in Liberty, NC. Participants in the workshop came from Texas, North Carolina, Virginia, Tennessee, Pennsylvania, Georgia, and Alabama.

Attendees were able to utilize the instruction by conducting hands-on lab exercises using NC State’s 1000 BF steam heated dry kiln. Throughout each day, participants sampled and measured moisture content of yellow poplar between lectures. They were tasked with performing moisture content calculations by hand and comparing those with a Delmhorst meter and a Wagner meter. Utilizing the kiln replicated industry standards and allowed participants to acquire first-hand experience with the techniques.

Upon introductions on the first day, attendees were given an educational binder that included the course outline, literature such as the Dry Kiln Operators Manual, recent articles, and multiple charts related to moisture content, drying times, etc. The instructional content began with Dr. Mitchell discussing Methods of Determining the Moisture Content of Wood where participants learned standard procedures for determining moisture content as well as formulas. Dr. Mitchell continued to discuss the importance of kiln samples and how to best utilize sampling methods. After laboratory exercises and lunch, Dr. Conners discussed Structure of Wood Related to Drying, Shrinkage and Wood Moisture Relations, and Temperature, Relative Humidity, and EMC Relationships.

Day 2 began with checking moisture contents of the samples taken on day 1 and comparing moisture contents. Dr. Mitchell then discussed Drying Schedules and How to Prevent Drying Stresses and Defects. Lunch was again catered and the group left to go to Edwards Wood Products Sawmill in Liberty, North Carolina. Edward’s Sawmill is the second largest hardwood sawmill producer in the United States and was able to provide a hands-on view of modern sawmill operations. A few miles down the road the next visit was Edwards Wood Products Kiln Operation also in Liberty, NC. The manager of the kiln operation attended the short course last year and was able to show everyone the sampling methods the course teaches used in an industry setting. The tour included stops at sampling ovens, lumber stacks, size sorters, processing equipment, and a 50,000 BF Kiln.

Day 3 began with the continuation of lab measurements and transitioned to Niels Jorgensen, President of, discussing Basic Kiln Features. Mike Sanders, Construction and Service Manager of USNR, then spoke on Controllers/Recorders Their Function and Maintenance as well as Trouble Shooting Using Kiln Charts. The day concluded with participants recording sample moisture contents and comparing results.

The final day began with final calculations of moisture content using the Delmhorst meter, Wagner meter, and hand-done formulas. The group then conducted a stress test on a random sample of the yellow poplar to find the sample displayed casehardening. Dr. Laleicke provided instruction on Moisture Meters and Auxiliary Equipment where airflow meters, hygrometers, self-calculation balances and scales, ovens and more were discussed. Dr. Mitchell concluded the instructional period by discussing Equalizing and Conditioning as well as Air Drying and Pre-drying Principles. At the end of the session, participants were awarded certificates and contact information for further questions.