processing of paint is the incorporation of the
five classes of raw materials to form a
free-flowing suspension of a pre-determined
shade. The first and major process in paint
manufacture is dispersion of the pigment.
Pigments and extenders,
when recieved, are composed of fairly large
aggregates and agglomerates, although on inital
inspection they may appear as finely divided
Dispersion is the process
whereby the pigment agglomerates/aggregrates are
reduced to the size required. A high gloss paint
will require very finely dispersed pigments
while a primer or a satin finish will require a
slightly coarser particle size.
When the desired size is
achieved, the dispersed pigments are stabilized
to prevent reformation of the aggregates. This
is done by using more binder and wetting agents.
After stabilisation, yet
more binder, solvent and finally additives are
blended to complete the paint.
In each paint, the
quantities of each class of raw material are
determined by the properties desired.
The end use of a paint
determines the raw materials to be used.
Exterior paints should be formulated with light
fast pigments whereas a paint designed only for
interior use could be based on bright coloured
pigments as fading is not a critical factor.