Plywood is a type of engineered wood made from thin sheets of wood, called plies or wood veneers. The layers are glued together, each with its grain at right angles for greater strength. There're usually an odd number of plies, as the symmetry makes the board less prone to warping The adhesives used in plywood have become a point of concern. Both urea formaldehyde and phenol formaldehyde are carcinogenic in very high concentrations. As a result, many manufacturers are turning to low formaldehyd… (More on Plywood)