1. Do You Always Adjust Test
Results To 12 % MC?
NO!
David W. Patterson
Professor Emeritus
Jonathan Hartley
Program Technician
Arkansas Forest Resources Center
University of Arkansas - Monticello
2. Introduction
• I have reviewed many manuscripts
submitted for publication
• Many Authors feel obligated to
mathematically adjust everything to
12% MC before analyzing the data
• This can be Good!
• This can be Bad!
3. Tests Methods
• Species – pine, red oak, sweetgum
• Size – 4 cm by 4 cm by 25 cm
• Replications: 10
• All Dried at 50°C
• Treatments: Control, 100, 150, 200°C
• Duration: 6 hours
• Conditioning Time: 2 months
• Conditioning Environment
– Condition Chamber
– Outside Air
– Enclosed Over Water
10. Condition Chamber
Moisture Contents
Species C/50 100 150 200
Pine 13 12 11 8
Red Oak 12 12 8 6
Sweetgum 13 12 11 8
11. Outside Air
Moisture Contents
Species C/50 100 150 200
Pine 14 13 12 10
Red Oak 13 11 8 6
Sweetgum 14 13 12 9
12. Enclosed Over Water
Moisture Contents
Species C/50 100 150 200
Pine 18 15 13 11
Red Oak 15 12 10 7
Sweetgum 17 14 12 10
13. Some Mechanical Properties
• All 3 Species
• 5 Replications
• Controls and 200°C
• Condition Chamber and Enclosed Over
Water
• Tested in Compression Parallel to the
Grain
14. Test Results
PSI
Species CC EOW
C/50 200 C/50 200
Pine 5269 6475 4271 5501
Red Oak 5424 7109 5551 6782
Sweetgum 5546 7009 5010 6169
15. Do Not Adjust for MC if the
Samples Were Conditioned
Under the Same
Environment and for
Sufficient Time to Equalize.
16. In 1986 there was an editorial in
the W&FS journal about not
adjusting specific gravity if the
difference was caused by the
treatment.
