I

Impact modifier
Additive that changes the ability of a coating to resist sudden pulls or shocks.

Impact resistance
Ability of a coating to resist deformation or cracking due to a forceful blow.

In-Can preservative
Water-soluble biocide used to protect wet paints against biodegradation (caused by fungi or bacteria) during storage.

Incompatibility
Opposite of Compatibility.

Inert pigment
Non-reactive pigment, filler, or extender.

Inhibitive pigment
Pigment which allows inhibiting corrosion.

Initiator
Additive which helps to start polymerization.
Examples of initiators are peroxides.

Ink
Colored or pigmented liquid or paste composition which consists of two parts: varnish and color.

Inorganic pigment
Natural or synthetic pigment such as metallic oxide, sulfide, and other salts. Possesses outstanding heat- and light-stability, weather resistance, and migration resistance.

Insecticidal material
See Preservative

Intercoat contamination
Presence of dust, dirt or of other foreign matter between successive coats of paint.

Intercoat adhesion
Adhesion between successive coats of paint.
Syn. Interlayer adhesion

Internal mix
Spray gun in which the fluid and air are combined before leaving the gun.

Internal stress
Mechanical stress caused by contraction of the cured coating film, due to evaporation of solvents, curing, difference in temperature or aging. This mechanical stress can induce coating defects such as delamination, cracking... . Internal stress can be reduced using plasticizers, optimizing film curing, or lowering film thickness.

Intumescent coating
Fire retardant coating which, when heated, produces non-flammable gases which are trapped by the film, converting it to a foam, thereby insulating the substrate.

Intumescent additive
Additive used in fire retardant coatings. Forms a foam produced by nonflammable gases, inhibiting flame propagation on the coating.
See Intumescent coating