Functions ~ the main functions of paint are to provide:†- An economic method of surface protection to building materials
and components. - An economic method of surface decoration to building materials
and components.
Composition ~ the actual composition of any paint can be complex
but the basic components are:†- Binder ~ this is the liquid vehicle or medium which dries to form
the surface film and can be composed of linseed oil, drying oils,
synthetic resins or water. The first function of a paint medium
is to provide a means of spreading the paint over the surface
and at the same time acting as a binder to the pigment. - Pigment ~ this provides the body, colour, durability, opacity
and corrosion protection properties of the paint. The general
pigment used in paint is titanium dioxide which gives good
obliteration of the undercoats. Other pigments include carbon
black and iron oxide. - Solvents and Thinners ~ these are materials which can be
added to a paint to alter its viscosity. This increases
workability and penetration. Water is used for emulsion paint
and white spirit or turpentine for oil paint. - Drier ~ accelerates drying by absorbing oxygen from the air
and converting by oxidation to a solid. Soluble metals in
linseed oil or white spirit.
Paint Types † there is a wide range available but for most general
uses the following can be considered:†- Oil Based paints † these are available in priming, undercoat
and finishing grades. The latter can be obtained in a wide
range of colours and finishes such as matt, semi†matt,
eggshell, satin, gloss and enamel. Polyurethane paints have a
good hardness and resistance to water and cleaning. Oil
based paints are suitable for most applications if used in
conjunction with correct primer and undercoat. - Water Based Paints † most of these are called emulsion paints the
various finishes available being obtained by adding to the water
medium additives such as alkyd resin & polyvinyl acetate (PVA).
Finishes include matt, eggshell, semi-gloss and gloss. Emulsion
paints are easily applied, quick drying and can be obtained with a
washable finish and are suitable for most applications.
Paints and Painting