Correct option is C
Plywood
• Wood is a hygroscopic material and has ability to exchange its moisture content with air. Many mechanical properties are affected by changes in moisture content.
• The exchange of moisture depends upon the relative humidity and temperature of air and on the amount of water present in the wood. This relation has great influence on the properties and quality of manufactured plywood.
• The Bureau of Indian Standards (BIS) recommends a moisture content of 5%-15% by weight for plywood. Moisture content above or below this range can have adverse effects on the manufactured products and the environment.
• The plywood boards are prepared from thin
layers of wood or veneers. So Plywood is specified by the number of layers,
• The three or more veneers in odd numbers are placed one above the other with the direction of grains of successive layers at right angles to each other.
• They are held in position by application of suitable adhesives. The placing of veneers
normal to each other increases the longitudinal and transverse strengths of plywood.
• The tensile strength and compressive strength along(parallel) the grain shall be greater than that across(normal) the grain.
