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

Reducer:
Material that lowers a paint's viscosity but is not necessarily a solvent. (See Diluent.)

Reflectance:
The ratio of the light that radiates onto a surface to the amount that is reflected back.

Related Colours:
Two colours that are next to each other on the colour wheel.

Resin:
A natural or synthetic material utilised as the binder for a paint or sealant. Term used generally for oil-based or acrylic binders, as "alkyd resin" or "acrylic resin."

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