Module 3 Flashcards
Wood
Organic material that is naturally grown, and the variability within a species due to genetic and environmental influences is substantial
Wood (as construction material)
The general name for wood materials
Timber
Conversion and processing of wood
Plainsawn, Riftsawn, and Quartersawn
Typical applications of wood
Framing, Formworks, Interior Design, Bridge, Walkways, Furniture
Three types of Timber
Hardwood, Softwood, and Manufacturing Board
Produced from broad-leaf trees that lose leaves (deciduous trees) in winter (example: Oak)
Hardwood
Produced from trees that do not lose their leaves (coniferous trees)
Softwood
Manmade boards; made by gluing wood layers or fibers together (for example: plywood, MDF)
Manufactured Board
A property of wood that has physical properties according to their major orthogonal planes or “cardinal directions in wood”
Anisotropic Material
Along the length of the log, parallel to the grain
Longitudinal
With respect to the center of the log, vertical vertical-grained board
Radial
With respect to the growth rings
Tangential
It has an affinity for water molecules, causing swelling and shrinking as the material reaches equilibrium with its environment
Hygroscopic Material
Exhibits both viscous and elastic characteristics when undergoing deformation
Viscoelasticity
The weight of water as a percentage of the weight of an oven-dry sample of wood (30%-200%)
Moisture Content
The weight at which the cell cavities are empty but the cell walls are fuller (approx. 28% moisture content)
Fiber Saturation Point
Dependent on a range of characteristics, the importance of which depends on how the piece is intended to be used
Performance Properties
Characteristics of wood
Strength, Stiffness, Hardness, FInish Retention, Treatability with Preservatives, and Resistance (Shrinkage/Swelling, Checking, Decay, Color Changes, Warping, Weathering, Photodegradation, and Insect Attack)
Wood Density Formula
Oven dry mass of wood / Volume of wood
Specific Gravity Formula
Density of material / Density of water
Refers to the loss of the ability of a wood product to serve its intended purpose in appearance, strength, or other functions
Deterioration
Any irregularity or deviation from the qualities that make wood suitable for a particular purpose
Defect (applied to wood)
Causes surface erosion or photodegradation, a photochemical process that disintegrates the wood cell wall
Exposure to Light
Cyclical pressure to weathering elements leading to degradation
Exposure to moisture and heat cycles
Cause changes in shape, called “warp,” due to different rates of shrinkage in different directions
Changes in moisture content
Types of warping
Bow, Crook, Cup, and Twist
Attacks wood products for food and/or habitation
Insects
Fungi live by digesting food manufactured by other plants
Decay
Fungi produce dark-gray-to-black colorations, affecting the appearance of wood products and structural characteristics
Molds and Mildews
Principal Effects
Surface Erosion
Checking, splitting, and warping
Shrinkage and swelling
Disintegration and decay
Protective coatings
Paint, Stains, and Water Repellants
