Railroading – Horizontal rather than vertical application of a wall covering.

Re-coat Time - Interval required between the application of successive coats of paint. This time period is usually listed on the label.

Red Lead – An oxide of lead used in pigment form as a rust inhibitor.

Reducer – A material which lowers viscosity, usually a solvent for the particular film-former; thinner.

Reflectance – The ability of a film to reflect the light striking it.

Refraction – The bending of a ray of light passing through a material.

Refractive Index – A measure of the degree or amount of refraction of a material; in pigments, the higher the refractive index, the greater its hiding power.

Regulator – A valve used to reduce pressure.

Related Colors - Two colors that are next to each other on the color wheel.

Repainting – A complete painting operation including surface preparation of a previously coated surface.

Resin – A material, natural or synthetic, contained in varnishes, lacquers, and paints; the film former.

Respirator – Safety breathing mask.

Retreating Colors – Colors that seem to move away or make an object or surface seem farther away from a viewer.

Roller Coating – The act of painting with a roller.

Runs – Curtains; sags.

Rust - The reddish, brittle oxide formed on iron or its alloys. It is a result of exposure to air and humidity or chemicals.