| Off-Gassing | Offgassing is the evaporation of volatile chemicals in non-metallic materials at normal atmospheric pressure. This means that building materials can release chemicals into the air through evaporation. This evaporation can continue for years after the products are initially installed which means you continue to breathe these chemicals as you work, sleep and relax in your home or office. |
| Oil Paint | A paint containing a suspension of pigments in an organic solvent and a drying oil, modified drying oil, or synthetic polymer that forms an opaque film through a combination of solvent evaporation and curing of the oil or polymer. |
| Old Growth | Timber in or from a mature, naturally established forest. When the trees have grown during most if not all of their individual lives in active competition with their companions for sunlight and moisture, this timber is usually straight and relatively free of knots. |
| Oleoresin | A solution of resin in an essential oil that occurs in or exudes from many plants, especially softwoods. The oleoresin from pine is a solution of pine resin (rosin) in turpentine. |
| Open Assembly Time | The time interval between the spreading of the adhesive on the adherend and the completion of assembly of the parts for bonding. |
| Open-Grained Wood Grain | Common classification for woods with large pores such as oak, keruing, meranti, and walnut. Also known as "coarse textured." |
| Operational Energy | The energy used by a product to operate. |
| Oriented Strand Board (OSB) | Wood panels made from wood fibers and chips that are mixed with resin and raked to orient them in the long direction of the panel to maximize strength. OSB, made from what is essentially a waste product, can replace plywood, saving lumber. A concern, similar to many manufactured products, is off-gassing from the resin binder. |
| Oriented Strandboard | A type of particle panel product composed of strand-type flakes that are purposefully aligned in directions that make a panel stronger, stiffer, and with improved dimensional properties in the alignment directions than a panel with random flake orientation. |
| Ovendry Wood | Wood dried to a relatively constant weight in a ventilated oven at 102¡C to 105¡C (215¡F to 220¡F). |
| Overlay | A thin layer of paper, plastic, film, metal foil, or other material bonded to one or both faces of panel products or to lumber to provide a protective or decorative face or a base for painting. |
| Ozone | A molecule that occurs naturally in the earth's atmosphere: both the upper atmosphere (called the stratosphere) and the lower atmosphere (called the troposphere). It is important to life on earth primarily because it absorbs biologically harmful ultraviolet radiation, preventing it from reaching the earth. (See Ozone Depletion) |
| Ozone Depletion | Nitrogen oxides, chlorine oxides, hydrogen oxides, and bromine oxides destroy the ozone. Chlorine and bromine reactions are the most detrimental, which include chlorofluorocarbons reactions. |