GLOSSARY 

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N 

NAIL POPPING

A slight protrusion of nail heads from drywall panels that can be caused by shrinkage of lumber framing, structural movement, or improper application of the fasteners. 

NAP

The length of fibres in a paint roller cover, usually described as "short nap," "long nap," etc. 

NAPHTHA

Any of several hydrocarbon solvents or their mixtures that are derived from petroleum or coal tar products. Generally, these solvents are composed of aliphatic (VM&P naphtha) or aromatic (high flash naphtha) compounds. 

NAPHTHENIC SOLVENT

Hydrocarbon solvent comprised primarily of ring compounds of saturated hydrocarbons (cycloparaffinic, naphthenic). These solvents fall between aliphatic and aromatic solvents. Examples are cyclopropane, cyclobutane, cycloheptane, and cyclohexane. 

NATURAL RESIN

Solid organic substance, originating in the exudation of trees or plants, the secretion of insects, or fossilized vegetable matter in the earth. These resins are thermoplastic, flammable, and nonconductive of electricity. When hard, they break with a conchoidal fracture (a fracture whose surface resembles the inside of a clam shell), and they dissolve in certain specific organic solvents but not water.  

NEAR-WHITE BLAST CLEANING

High grade of blast cleaning. This standard surface is defined in two slightly different consensus standards. 

NEEDLE GAUGE

An air pressure gauge with a needle connected to the air inlet. A needle gauge is used to check the air pressure of a blast system by inserting the needle into the blast hose just behind the nozzle and pointing the tapered tip into the air flow.  

NEEDLE GUN

A type of power impact tool that has a bundle of steel needles mounted in front of a piston that strikes them several times per second and impacts them against the surface being cleaned. 

NEUTRALIZATION

The process of removing excess acidity or alkalinity from concrete, masonry, or plaster. 

NONFLAMMABLE

Incombustible; will not burn. 

NON-GRAIN-RAISING STAIN

A solution of dye dissolved in alcohol, ketone, etc. Because it contains no water, it does not raise the grain of woods. 

NONMETALLIC ABRASIVE

Natural, by-product, and manufactured materials used as abrasives for blast cleaning. 

NVM - NONVOLATILE MATTER

The volume of dry (cured) coating expressed as a percentage of the volume of liquid coating applied to a surface (e.g., vol. of NVM is 62 percent). This value is useful for comparing the coverage obtainable with different coatings. Often, percentage is given without specifying whether it refers to volume or weight. This is confusing and can lead to errors in coating calculations.  

NONWOVEN ABRASIVE PAD

A web of nylon fibres imbedded with abrasive material in different sizes and densities. These pads can be used to remove dried soil, debris, and loose paint from all types of surfaces, as well as loose rust and loose mill scale from steel. They also can be used to feather, or blend the edges of a repair area, with the surrounding surface. 

NOZZLE

The fluid orifice of an airless spray gun. 

NOZZLE ORIFICE GAUGE

A tapered metal rod that can be inserted into a blast cleaning nozzle to determine the size of its orifice. The nozzle normally is replaced when the orifice size increases by 1/16 inch.