Painting

Paint is a liquid which dries to form a surface. It is used in Engineering for protection, decoration and identification of surfaces.

Paint consists mainly of:

Pigments, which provide opacity and colour and can affect the degree of gloss Binders, which keep the powdery pigment together . Solvents (and thinners and dispersing agents), which evaporate after application to leave behind the film of bound pigment.

When painting surfaces a "paint system" is generally used including the following stages:

Surface preparation Application of a Primer layer. Application of an Undercoat layer. Application of a topcoat.

It is preferable to obtain the primer, Undercoat and the topcoat from the same manufacturer.

A Paint can be either water based or solvent based.

In a solvent based paint a solvent is used with the binder to obtain suitable consistency for applying the paint. The solvent evaporates after application. The binder forms a film which hardens generally as a result of chemical reaction . In production processes the hardening/ curing process is accelerated using additional processes including stoving in special ovens. In the curing process the binder changes chemically and is no long soluble in the solvent.

Laquers are solvent based paints that simply harden as a result of the solvent evaporation with no chemical change to the film.

Water based paints are either

Emulusions of polymers depending on for their drying properties on the evaporation of water and coalescing of the polymer particles. Water soluble resins which are applied by electro-deposition or by dipping followed by stoving.