R

Rabbit Ears
Spray pattern often seen with airless spray. The edge of the pattern separates to form a single stream.

Radiation cured coatings
See UV/EB cured coating

Refinishing
Coating material that has been formulated to reproduce, as closely as possible, the color, gloss and durability of the coating material that was applied originally to an automotive body and which has been subsequently damaged or has deteriorated.

Reflectance
Ratio of the intensity of reflected light to that of incidental light.

Relative humidity
Ratio of the quantity of water vapor present in the air to the greatest amount possible at a given temperature (expressed as a percent).

Release agent
Additive which imparts coatings with extremely low surface energy and anti-stick properties.

Relief coating
Coating with controlled structure of their top surface.

Resin
Solid, semi-solid or pseudo-solid organic material which has an indefinite and often high molecular weight. Exhibits a tendency to flow when subject to stress. Can be natural or synthetic.

Retarder
Solvent added to a paint to slow down its evaporation rate.

Reverse emulsion
Emulsion of water-in-oil type.

Rheology
Science characterizing fluid deformation or flow.

Rheology modifier
Additive used to raise or control the viscosity, the rheology of a paint or pigment preparation. Effects the flow properties of liquid systems in a controlled and predictable way. Used in water-based and solvent-based paints. Rheology modifiers are generally considered as being either pseudoplastic or thixotropic in nature.

Roller
Cylinder covered with lamb's wool, felt, foamed plastics, or other materials used for applying coatings.

Rub-up
Color change which results from rubbing a portion of the applied coating during rub-out test.

Runs
Coating defect: sagging and curtaining of a coating or paint film, usually caused by improper thinning, excessive film build, or poor application techniques.