MASTIC: A coating material of relatively thick consistency.
MATERIAL SAFETY DATA SHEET (MSDS): A standard formatted information sheet prepared by a material manufacturer that describes the potential hazards, physical properties, and procedures for the safe use of a material.
MDI: See METHYLENE DIPHENYL DIISOCYANTE.
MECHANICAL BOND: See BOND, MECHANICAL.
MECHANICAL DAMAGE: Breaks or punctures to insulation and coating systems as a result of impact or abrasion.
MEDIUM-DENSITY SPF (CLOSED CELL SPF, ccSPF): A type of SPF expanded with non-reactive blowing agents to yield a rigid cellular structure. It is characterized by a predominance of closed cells and a density between 1.5–2.5 lb./ft3.
MEMBRANE: A layer of material that acts to prevent the passage of a substance. Membranes may restrict the passage of air, liquid water, or water vapor. Some membranes allow the passage of some substances, while excluding others.
MEMBRANE REINFORCEMENT: Fabrics or fibers embedded in mastic or coating to provide strength and impact resistance.
METHYLENE DIPHENYL DIISOCYANATE (MDI): Component-A in SPF. An organic chemical compound having two reactive isocyanate (-N=C=O) groups. It is mixed with the B-component to form polyurethane.
MIL: One-thousandth of an inch; 0.001 in. (0.025 mm). A unit used to measure coating thickness.
MILDEW: A superficial coating or discoloring of an organic material due to fungal growth, especially under damp conditions.
MIST COAT: A very thin sprayed coat.
MOLD: Fungal growths often resulting in deterioration of organic materials, especially under damp conditions.
MOISTURE VAPOR TRANSMISSION (MVT): See WATER VAPOR TRANSMISSION, DIFFUSION.
MONOLITHIC: Formed from or composed of a single material; seamless.
MSDS: See MATERIAL SAFETY DATA SHEET.
MUD-CRACKING: The defect in an applied coating or mastic when it cracks into large segments or shrinks (also called alligatoring). When the action is fine and incomplete, it is usually referred to as “checking.”MULTIPLE COAT: Two or more layers of coating applied to a substrate.
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