V

Vapor barrier
Layer which prevents the passage of water into a material or structure.

Varnish
Inpigmented binder-solvent solution that is converted to a transparent or translucent solid film after application as a thin layer. Varnish is pplied to protect or decorate a surface.
Syn. Clearcoat

Vehicle
Liquid portion of a paint in which the pigment is dispersed. Comprised of binder and thinner.

Vinyl copolymer
Resin resulting of the copolymerization of vinyl acetate and vinyl chloride.

Viscoelastic flow
Flow behavior of a liquid (or solid) having both viscous and elastic properties. A viscoelastic liquid will deform and flow under the influence of an applied shear stress, but when the stress is removed, the liquid will slowly recover from some of the deformation. Viscoelastic flow is characteristic of some gel-like substances and low Tg polymers (plasto-elastomers).

Viscosity
Measurement of a fluid's resistance to flow. The common metric unit of absolute viscosity is the poise, which is defined as the force in dynes required to move a surface one square centimeter in area past a parallel surface at a speed of one centimeter per second, with the surfaces separated by a fluid film one centimeter thick. Since viscosity varies in inversely with temperature, its value is meaningless until the temperature at which it is determined is reported.

Viscosity modifier
Additive modifying rheological behavior of a polymeric composition.
Syn. Rheology modifier, Thickener

Viscosity profile (extended definition)
Graphic representation of the shear viscosity function versus the shear rate or the shear stress.
Syn. Viscosity curve

V.O.C.
Volatile Organic Compound or liquid that is non-exempt.

Voids
Coating defect: holes in a coating application.

Volatile
Amount of solvent or liquid components in a coating.

Vulcanization
Irreversible process during which an elastomer, through a change in its chemical structure (for example crosslinking), becomes less plastic and more resistant to swelling by organic liquids. Its elastic properties are conferred, improved, or extended over a greater range of temperature.

Vulcanizing agent
Compounding material that produces vulcanization.