Common defects that occur in timber include knots, shakes, wind cracks, upsets, twisting, cupping, bowing, rot and insect damage. These defects are typically grouped into three categories: defects caused by natural forces, defects caused by defective seasoning and conversions and biological defects.Know More
Knots, shakes, wind cracks and upsets are defects caused by natural forces. Knots are the hardened stumps of broken or sawn branches, which can weaken or disfigure the surface of timber. Shakes are cracks in the timber caused by excessive heat, frost or twisting due to wind. Wind cracks are the cracks that appear on the outside of a log due to the shrinkage of the exterior surface. Upsets are defects in the grain caused by excessive compression or crushing of the tree when it is young.
Twisting, cupping, bowing are defects caused by defective seasoning and conversion. Twisting occurs when constriction causes the edges of a piece of timber to move out of parallel. Cupping is when the timber dries out in a curved shape. Bowing is a warp along the length of the face of the wood.
Rot and insect damage are biological defects. Rot most often occurs due to the presence of fungi in the timber. Insects weaken the timber because they eat the wood.Learn more about Building Materials
The Parthenon of Ancient Athens was made of hand-carved pentelic marble from top to bottom, with some timber to support the slanted marble tiles of the roof. The segments of the columns were internally secured by iron clamps with a layer of molten lead. The statue of Athena Parthenos inside the Parthenon had ivory skin and nearly 2,400 pounds of gold armor, weapons and jewelry.Full Answer >
The timber, prairie and Massasauga rattlesnakes can all be found in Iowa and are generally considered to be the only poisonous snakes native to the state. Rarely, copperheads can be found in localized areas in south-eastern Iowa.Full Answer >
According to the University of Minnesota, microorganisms such as wood-decay fungi cause billions of dollars in losses every year by destroying forest trees that could have been used as timber. They are also useful if used in medicines, wood products and agriculture. Microorganisms play a role in breaking down decomposing matter, but the bacteria also causes gas release and a putrid odor.Full Answer >
The most common natural resources of Cuba are cobalt, nickel, iron ore, chromium, copper, salt, timber, silica, petroleum and arable land. The by-products of arable land in Cuba, namely sugar, tobacco and rum, are the most important export items of the Cuban economy.Full Answer >