insulation, but is applied with a small quantity of water to help the cellulose bind to the inside of open wall cavities, and to make the cellulose more resistant to settling. Spray application provides even better protection against air infiltration and improves wall rigidity. It also allows application on sloped walls, attics, and similar spaces. Wet-spray is best for new construction, as the wall must be allowed to dry completely before sealing with drywall (a moisture meter is recommended). Moist-spray (also called stabilized) cellulose uses less water to speed up drying time. Fiberglass. Usually pink, yellow, or white. Loses effectiveness when moist or wet, but does not absorb much water. Nonflammable. See Health effects of fiberglass. Natural insulations such as granulated cork, hemp fibres, grains, all which can be treated with a low toxicity fire and insect retardants Vermiculite. Generally gray or brown. Perlite. Generally white or yellow. Cotton, wool, hemp, corn cobs, strawdust and other harvested natural materials. Not common. Granulated cork. Cork is as good an insulator as foam. It does not absorb water as it consists of closed cells. Resists fire. Used in Europe. Most plant based insulations such as wood chips, wood fiber, sawdust, redwood bark, hemlock fiber, balsa wood, hemp fiber, flax fiber, etc. are hygroscopic. Wood absorbs water, which reduces its effectiveness as a thermal insulator. In the presence of moisture, wood is susceptible to mold, mildew, and rot. Careful design of wall, roof and floor systems as done in Europe avoid these problems which are due to poor design. Regulations US regulatory standards for cellulose insulation 16 CFR Part 1209 (Consumer Products Safety Commission, or CPSC) – covers settled density, corrosiveness, critical radiant flux, and smoldering combustion. ASTM Standard C-739 – loose-fill cellulose insulation – covers all factors of the CPSC regulation and five additional characteristics, R-value, starch content, moisture absorption, odor, and resistance to fungus growth. ASTM Standard C-1149 – Industry standard for self-supported spray-applied cellulose insulation for exposed or wall cavity application – covers density, R-value, surface burning, adhesive strength, smoldering combustion, fungi resistance, corrosion, moisture vapor absorption, odor, flame resistance permanency (no test exists for this characteristic), substrate deflection (for exposed application products), and air erosion (for exposed application products). 16 CFR Part 460 – (Federal Trade Commission regulation) commonly known as the "R-Value Rule," intended to eliminate misleading insulation marketing claims and ensure publication of accurate R-Value and coverage