W

Wash primer
Thin paint, usually a chromate, designed to promote adhesion or to be used as a barrier coat.

Water repellent
Additive which exudes to the coating surface and forms a thin, transparent and durable protective barrier. The coating surface becomes hydrophobic and has non-wetting and water-proofing properties.

Water scavenger
Syn. Moisture scavenger

Water spotting
Coating defect: change in surface appearance due to the action of water standing on the paint film or substrate.

Water-retention agent
Additive used to slow down drying of latex paints and to prolong open-time.

Wax
Solid or semi-solid material derived from petroleum distillates or residues by such treatments as chilling, precipitating with a solvent or de-oiling. It is a light-colored, more-or-less translucent crystalline mass, slightly greasy to the touch, consisting of a mixture of solid hydrocarbons in which paraffin series predominates. Can be used as surface conditioner or rheology modifier.

Weathering
Surface deterioration of a coating surface during outdoor exposure. The use of antioxidants, UV light stabilizers, etc... permits to have a greater weathering.
Syn. Aging

Wet edge
Ability of a wet coating to blend smoothly together in the overlap areas during application.

Wet-edge extender
Syn. Substrate wetting agent

Wet on wet
Technique of painting whereby the second coat is applied before the first coat has dried and the composite film dries as a whole.

Wetting (extended definition)
Impregnation of a material by a liquid by replacement of an air/solid interface by a liquid medium/solid interface.

Wetting agent
Substance used to reduce the surface tension and thereby facilitate spreading or impregnation of a surface. Additive that belong to the group of surfactants.
Syn. Dispersing agent , Dispersant, Grinding aid, Milling aid

Wicking action
Capillary drawing action bringing oil to the surface.

Wrap around
Phenomenon by which electrically charged paint droplets curve around the rear side of the object being painted.

Wrinkling (extended definition)
Coating defect: skinning over of the film surface and absorption of the liquid within the film.