section_path: Physical properties/Density
section_name: Density
paragraph_text: Density
  
  Wood density is determined by multiple growth and physiological factors compounded into "one fairly easily measured wood characteristic" (Elliott 1970).
  
  Age, diameter, height, radial (trunk) growth, geographical location, site and growing conditions, silvicultural treatment, and seed source all to some degree influence wood density. Variation is to be expected. Within an individual tree, the variation in wood density is often as great as or even greater than that between different trees (Timell 1986). Variation of specific gravity within the bole of a tree can occur in either the horizontal or vertical direction.
  
  Because the specific gravity as defined above uses an unrealistic condition, woodworkers tend to use the "average dried weight", which is a density based on mass at 12% moisture content and volume at the same (ρ). This condition occurs when the wood is at equilibrium moisture content with air at about 65% relative humidity and temperature at 30 °C (86 °F). This density is expressed in units of kg/m or lbs/ft.