1. Composite Panel Products for Stage Scenery 2005 USITT Conference & Stage Expo, Toronto, CA March 16-19, 2005 John F. Hunt, P.E. Research Mechanical Engineer USDA, Forest Products Laboratory, Madison, WI, USA

2. Overview Wood Composite Panels Wood and Moisture Effects of Moisture on Panel Properties Comments 2005 USITT Conference & Stage Expo, Toronto, CA March 16-19, 2005

3. Chapter 10 from the Wood Handbook www.fpl.fs.fed.us 2005 USITT Conference & Stage Expo, Toronto, CA March 16-19, 2005 Wood Composite Panels

5. Wood-based Composite Panels come in a variety of configurations giving various performance properties. 2005 USITT Conference & Stage Expo, Toronto, CA March 16-19, 2005 Wood Composites

6. 2005 USITT Conference & Stage Expo, Toronto, CA March 16-19, 2005 All Plywood Panels are not equal. Plywood Properties by Species

7. Wood Composite Panels

8. 2005 USITT Conference & Stage Expo, Toronto, CA March 16-19, 2005 Wood Composite Panels

12. Sheathing Plywood Sheathing OSB Particle- board MDFHardboard Linear hygroscopic expansion 0.15% 0.35% Bending Modulus of Rupture (MPa) 20.7–48.320.7–27.63 – 23.514 - 34.531 – 41.2 Modulus of Elasticity (GPa) 6.89–13.14.83–8.270.5 - 2.753.45 Tensile Strength (MPa) l0.3–27.66.9–l0.315.2 Compression Strength (MPa) 20.7–34.56.9–l0.3 Shear Through Thickness Shear Strength (MPa) 4.1–7.66.9–l0.3 Shear Modulus (GPa) 0.47–0.7611.24–2.00 Shear In-Plane Shear Strength (MPa) 1.7–2.11.38–2.1 Shear Modulus (GPa) 0.14–0.210.14–0.34 2005 USITT Conference & Stage Expo, Toronto, CA March 16-19, 2005 Wood Composite Panels

13. Wood and Moisture Wood takes on moisture slowly but also gives up moisture even slower.

14. Determining the moisture content of a piece of wood from relative humidity and temperature measurements. Wood and Moisture

15. Determining the moisture content of a piece of wood from painting. For example, if 1 gallon of paint with 40% solids were painted at a rate of 1gallon/200ft^2. Then for: Hardboard: approximately 2% absorption of water into the face of the panel (½ to the board ½ to evaporation). Particleboard: approximately 0.5% absorption of water into the face of the panel (½ to the board ½ to evaporation). Wood and Moisture

16. Comments If possible stand panels on their side for a short period of time to all equilibrium moisture absorption. If possible apply similar coatings to both sides to prevent warping. For some panels warping is a wood problem and may be difficult to over come. Cyclic moisture warping effects will occur on a set due to daily air-conditioning settings and heating due to lighting or other sources.