Non aqueous:-
A dispersion of a binder in an organic liquid which is a dispersant not a solvent for the binder. e.g. an organosol.

Non convertible:-
A binder which yields a film which, after drying, can binder be redissolved in its original solvent

Non volatile:-
The solid material remaining after the volatile has content been driven off or evaporated.

No Pick-Up Time:-
The period between the application of a film of a road-marking paint and the precise moment when the film is no longer removed by an apparatus that simulates the passage of a tyre over the surface of the film.

Opacity:-
The degree to which a material obscures or hides a substrate

Organosol:-
A composition based upon a resin solution in a volatile organic liquid. Often used in reference to aerosol paints where the propellant is a liquid/solvent under pressure.

Orange Peel:-
Surface mottled like skin of an orange. Caused by poor flow. Coats too thick. Surface drying too quick. Poor atomisation.

Osmosis:-
The passage of water in molecular form through a paint film (a semi-permeable membrane). Moisture will pass through a semi-permeable membrane if there is a soluble substance present - even in minute quantities. If the film with the solution thus formed (in or under it) is exposed to water with less solute (dilute) moisture will pass in the direction from the weaker to the stronger this creates a pressure (Osmotic pressure) and a bubble will form. See blisters.

Overprint Varnish:-
A clear coating material designed for use over films applied by a printing process.