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Paints
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Remember the advertisement in which a lady
searches high and low for a particular shade of paint that she
wants? The range of colors in which paints are available nowadays
allows customers to be as choosy as they want and use paints in
exactly the shade that they dream of. This has been made possible by
blending the knowledge of chemistry into the process of paint
manufacture. This development has been a continuous one that has
happened over a considerable period of time.
How long have
paints been in use?
The use of color to brighten living environs has been in
use since time immemorial. The ancient Egyptians used dyes to
make red and blue colors that were used to dye garments for the
nobility. The Chinese developed their own methods of adding
color to their surroundings. They used a base of wax, gelatin,
egg white and gum and added organic and inorganic pigments to
get a colorful liquid that could be spread on various surfaces.
The use of paints is evident in many cave paintings in various
places in the world. Such cave paintings can be found in India,
France and Spain.
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It was the introduction of the use of
linseed oil as a base in the 18th century that gave a
fillip to the widespread use of paint. After this, there was no
looking back. By incorporating scientific principles better,
more lasting paints were developed. Paints became universally
popular when it was seen that the use of paints enhanced
resistance to fire and retarded corrosion.
Pigment – the
all-important ingredient
Certain compounds are intensely colored and when added to other
materials, they impart their color to them. These compounds are
referred to as pigments. For example, chlorophyll is the compound
that imparts the color green to leaves.
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The pigments used to
impart color to paints may be either organic or inorganic. The
pigments used in earlier times were all organic pigments that
occurred naturally. But with an increased knowledge of chemistry
several synthetic pigments have been developed. The effect of these
synthetic pigments is that we get a wide range of shades in each
color to choose from. Coal tar and other petrochemicals are the
sources from which synthetic organic pigments are made. Several
inorganic pigments are used to lighten colors and produce varying
shades to satisfy an increasingly choosy and discerning clientele.
Color, color, what
color… and how
What is the secret behind the different colors? How are the
different hues imparted, and from where? Zinc oxide, zinc sulphide,
lithopone, and titanium dioxide are the chemicals used to impart
white color in paints. Black comes from carbon and minerals like
iron oxide. Cadmium and cuprous oxide are used for imparting a red
tint. Several synthetic pigments are also used for giving a red
tint. Chromates, molybdates and cadmium compounds contribute yellow
and orange. Both organic and inorganic pigments are used for
imparting the colors blue and green.
Research over the years
has yielded several products that enhance various aspects of paints
like their durability, sheen, ability to spread etc.
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