Evaporation rate:-
The time required for a given amount of a material to evaporate compared with the time required to evaporate the same amount of a known material (usually n butyl acetate or ethyl ether Standard must be quoted).

Face Colour:-
Term used to describe the colour observed on paints, (particularly metallic paints) when they are viewed near to the normal. It may also be referred to as the "Top Colour". It is generally used in contrast to the term "Flop Colour", which is the colour observed near to the grazing angle, ie. Nearly parallel to the surface (See FLOP COLOUR).

Fading:-
The loss of colour caused by a change in the colourant used in the film (pigment or dye). Generally the colour becomes lighter but any resistant colourants will dominate. Differs from chalking.

Fineness of grind:-
An assessment of the degree of dispersion as judged by the presence of coarse particles; a grind gauge is used for the purpose, See F.O.G.

Fish eyes:-
Small holes in the surface. Caused by oil grease or silicone contamination. See cissing,. Cratering

Flash point:-
The lowest temperature of a liquid at which it gives off sufficient vapour to form an ignitable mixture with the air at the surface of the liquid.

Flocculation:-
The formation of clusters of pigment particles in the liquid medium after dispersion. The condition is reversible, and weak mechanical forces e.g. stirring can break up flocculates.

Flop:-
Where two different painted panels appear to be a good match for colour when viewed at a given angle, but which appear different in colour at all other angles. Also known as Geometric Metamerism.

Flop Colour:-
Term used to describe the colour observed on paints (particularly metallic paints) when they are viewed near to the grazing angle, i.e. nearly parallel to the surface. The term is generally used in antithesis to the terms "Face Colour" or "Top Colour" - the colour observed when the surface is viewed at an angle near to the normal. (See FACE COLOUR).

F.O.G.:-
An assessment of the degree of dispersion as judged by the presence of coarse particles; a grind gauge is used for the purpose, See Fineness of grind.

Ford Cup:-
An effluent type viscometer of particular use in the measurement of non-thixotropic paints. The size of the aperture must be specified (ie No. 4). The time taken for the paint to drain from the cup is expressed in seconds at a set temperature.