Incompatibility – Not able to be mixed with other material, or not able to be applied to certain surfaces.

Indigo – A blue dye obtained from certain plants made synthetically.

Inert – Chemically inactive; resistant to corrosion.

Inert Pigment – (see Extender).

Inorganic – (Chemical) containing no carbon atom in formula.

Insoluble - The inability to be dissolved.

Intercoat - A layer of paint that is “sandwiched” between two others. Also refers to something occurring between coats, as in “inter-coat adhesion.”

Intermediate Colors – Colors on the color wheel which are mixtures of one primary and one secondary color.

Internal Mix – A spray gun in which the fluid and air are combined before they leave the gun.

Iron Oxide – (1) Natural occurring pigment available in three basic colors: red, brown and yellow; (2) Rust.

Intumescence - The ability of a fire retardant paint under high heat to swell an form a cellular barrier insulating the surface beneath.