Calculating the Equilibrium Moisture Content

The moisture content of wood in an environment held at the constant conditions of temperature and relative humidity will come to an equilibrium with its surroundings.  The air temperature and relative humidity will determine the equilibrium moisture content (EMC) conditions, and the moisture content of wood in that environment will approach the EMC of the air.  An Excel spreadsheet (titled “EMC Calculate”) is available that will calculate an estimate of the EMC based on the dry-bulb temperature and one of the following: relative humidity; wet-bulb temperature; or, dew-point temperature.

Download the EMC Calculate.xls spreadsheet (or email phil_mitchell@ncsu.edu to get the xlsx version).
Download the article:  Wood Products Notes: Calculating the Equilibrium Moisture Content for Wood Based on Humidity Measurements

NC STATE WOOD PRODUCTS EXTENSION UPCOMING EVENTS

  • Fall 2017 Southeastern Dry Kiln Club Meeting (Jointly with OVLDA), Alcoa and Vonore, TN, Nov. 2-3, 2017 (see below for more information)
  • 2017 Upholstery Frame Workshop, Conover, NC, Nov. 9, 2017. (contact Harry Watt: harry_watt@ncsu.edu or 704-880-3067 or see brochure)
  • Profitable Small Sawmills and Firewood Businesses Workshop, Spring or Summer of 2018.  (contact Harry Watt: harry_watt@ncsu.edu or 704-880-3067)
  • Automation Update for Cabinets, Furniture and Millwork, TBD, NC, late Winter 2018.  (contact Harry Watt: harry_watt@ncsu.edu or 704-880-3067)
  • Thick Lumber Slabs: Sourcing, Sawing, Air Drying, Kiln Drying, and Marketing, Western part of NC, Spring 2018.  (contact Harry Watt: harry_watt@ncsu.edu or 704-880-3067)
  • The 49th Annual Dry Kiln Operator’s Short Course, Raleigh, NC, June 5 – 8, 2018.  (contact Phil Mitchell: phil_mitchell@ncsu.edu)
  • NHLA Hardwood Lumber Grading Workshop, Raleigh, NC,  June 19 – 21, 2018.  (contact Phil Mitchell: phil_mitchell@ncsu.edu)

NC State Hosts NHLA Hardwood Lumber Grading Workshop

NHLA HARDWOOD LUMBER GRADING WORKSHOP
June 13 – 15, 2017
North Carolina State University
Raleigh, North Carolina

This popular workshop gives yardmen, sawyers, edger operators, sales and office staff, as well as management level personnel an introduction to lumber inspection. This course is designed as an introduction and a refresher course of the NHLA Rules. The course will cover the fundamental of hardwood lumber inspection and will give the attendees the opportunity for hands-on application of the rules.  Contact Phil Mitchell for more information:  (919) 515-5581 or phil_mitchell@ncsu.edu  or go to the web page.

NC State’s Dry Kiln Operator’s Workshop to be held May 16 – 19, 2017

THE 48TH ANNUAL HARDWOOD DRY KILN OPERATOR’S SHORT COURSE
Sponsored by the Southeastern Dry Kiln Club
May 16 – 19, 2017
NC State University
Raleigh, NC

This short course will provide practical knowledge about how lumber is effectively kiln dried and scientific background on related wood properties and processes.  It will have value for the beginner as well as experienced kiln operators and with supervisors, sales, and marketing personnel.  Instruction, by university faculty and industry experts, will be both in the classroom and through hands-on lab exercises using our 1000 BF steam heated dry kiln.

For program details contact Phil Mitchell at phil_mitchell@ncsu.edu or call 919 515 5581.   Registration and more details are available here.

The Equilibrium Moisture Content of Wood in Exterior Locations in the United States: An Update

Wood responds to atmospheric moisture in a predictable manner.  If the relative humidity and temperature of the air are known, we can determine the equilibrium moisture content of that air, or EMC.  Knowledge of the EMC is useful in estimating how fast lumber on an air drying yard will dry; how long it will take for kiln dried lumber to pick up moisture when stored in a warehouse; and the performance of finished wood products in exterior service.  The National Oceanic and Atmospheric Administration publishes 30-year Climate Normals for locations in the United States.  Climate Normals for 1981-2010 were used to determine the average monthly exterior EMC values for 252 locations in the US.

Download EMC’s in the United States’ Location (Excel spreadsheet)
Wood Products Notes:  The Equilibrium Moisture Content of Wood in Exterior Locations in the United States:  An Update

Differential Shrinkage and the Cupping of Lumber

Differential shrinkage of wood model.

Differential shrinkage of wood input/output page.

Wood shrinkage is often calculated with the assumption that the radial and tangential shrinkage occurs parallel to the surfaces of either flatsawn or quartersawn lumber.  As a result, the calculated shrinkage has a built-in error in calculating the change in dimension since it ignores the curvilinear nature of the growth rings.  An Excel spreadsheet model has been developed that considers the curvilinear nature of the growth rings in calculating the transverse wood shrinkage, and estimates the amount of cup that might develop. The model is dependent on wood species, initial and final moisture contents, and location of the board within the log.

Instructions on Using the Differential Shrinkage Model

Dehumidification Drying of Lumber Short Course

October 6-7, 2016
North Carolina State University
Raleigh, North Carolina

Registration Deadlines:
Friday, September 9, 2016 early discount fee ends
Friday, October 3, 2016 final registration day, limit 25 attendees.

Dehumidification drying can produce high quality kiln dried lumber with a small capital investment.  This short course will provide practical knowledge about using dehumidification to produce kiln dried lumber, and the scientific background on related wood properties. It will have value for those kiln operators beginning to operate a dehumidification kiln and those considering the purchase of a dehumidification kiln. Instruction, by university faculty, will be both in the classroom and through hands-on lab exercises using our 1000 BF laboratory dry kiln equipped with a commercial lumber dehumidification system. For more details: http://www.ncsu-feop.org/biomaterials/

NC State Announces 2016 NHLA Hardwood Lumber Grading Workshop

NHLA HARDWOOD LUMBER GRADING WORKSHOP

Sponsored by the Southeastern Dry Kiln Club
June 14 – 16, 2016
NC State University
Raleigh, NC

The value of “rules conscious” employees is a more carefully manufactured product, a more profitable yield from the log, and a better sense of the value of the lumber being handled. This three-day workshop will include a thorough study and explanation of the NHLA Rules Book, emphasizing the basics of hardwood lumber inspection.  This popular workshop gives yardmen, sawyers, edgermen, sales and office staff, as well as management level personnel an introduction to lumber inspection. This course is designed as an introduction and a refresher course of the NHLA Rules. The course will cover the fundamental of hardwood lumber inspection and will give the attendees the opportunity for hands-on application of the rules.

For more information:   go.ncsu.edu/hardwood-lumber-grading

May 2016 Graduates Looking for Full-Time Employment: Summer Interns Available

NC State University’s Sustainable Materials and Technology (SMT) program (formerly the Wood Products program) is part of the Forest Biomaterials Department.  SMT is an applied material science and engineering program focused on the economic, environmental, and social attributes of renewable materials (of which wood is the premier sustainable material). Our program provides specialized training and hands on experience regarding the responsible use of plant-based materials.  There are currently over 100 students working on their undergraduate degree in SMT, which is about triple the enrollment before the name change.
The Department of Forest Biomaterials at NC State offers employers access to a well-trained pool of the best and brightest young professionals in the sustainable materials and allied industries today.  We invite the Forest Products industry to consider our students for either full-time employment, or employment as a summer intern.
In addition to our graduates, SMT students are required to complete at least one summer internship in the industry.  Summer internships are a great opportunity for students to learn about the industry and to earn some money at the same time.  For the industry, having a summer intern is a means to hire temporary summer labor and evaluate that individual for possible future employment.
Please take a look at our Recruiter resources page:
Or, an employer can make an interview day request online:
Our Forest Biomaterials Career Services Coordinator is on temporary leave.  This Spring we are happy to have Cheryl Gill fill in.  You may contact her at:
Cheryl Gill               cgill@ncsu.edu                             (919) 515-2888
You may also contact either:
Phil Mitchell             phil_mitchell@ncsu.edu               (919) 515-5581
Perry Peralta           perry_peralta@ncsu.edu              (919) 515-5731

NC State announces Dry Kiln Operator’s Workshop to be held in May

ANNUAL HARDWOOD DRY KILN OPERATOR’S SHORT COURSE
Sponsored by the Southeastern Dry Kiln Club
May 17 – 20, 2016
NC State University
Raleigh, NC

This short course will provide practical knowledge about how lumber is effectively kiln dried and scientific background on related wood properties and processes.  It will have value for the beginner as well as experienced kiln operators and with supervisors, sales, and marketing personnel.  Instruction, by university faculty and industry experts, will be both in the classroom and through hands-on lab exercises using our 1000 BF steam heated dry kiln.

For program details contact Phil Mitchell at phil_mitchell@ncsu.edu or call 919 515 5581.   Registration and more details are available here.