Pigments are the reason for all things colorful! The bright reds of roses, dark blues of your jeans to the cheerful yellow splash in your bedroom are all a result of the existence of pigments. Pigments, by definition are substances that add color to an item. The term is quite often confused with dyes but in reality they can be said to be distant cousins. The main point of difference is that pigments can be dissolved in a liquid with the help of a binder while a dye can dissolve by itself.
Types of Pigments
There are basically two types of pigments and they are:
- Inorganic pigments
- Organic pigments
The first class of pigments occurs naturally and has a simple chemical structure. The mineral and metal content that lend them their color gives them their name of ‘inorganic pigments’. They are manufactured through a simple process which involves a procedure of washing, drying, powdering and combining into a formulation.
The term ‘organic pigments’ refer to pigments that are synthesized in the labs and hence there is greater control over their manufacture. Their levels of toxicity therefore are pretty low and so they do not pose an environmental hazard. They are used in large measure in the paints, plastics, synthetic fibers and inks industry and many other recent high-tech applications.
Another type into which pigments are classified is the metallic pigments and the industrial pigments. Metallic pigments include the zinc and aluminum pigments. Industrial pigments refer to those pigments that are widely used in the industrial applications and include organic, inorganic and the metallic pigments.
Essentials of a Good Pigment
Pigments possess certain attributes that make it suitable for use in several applications. Some properties that make for a good pigment include the following:
- Maximum covering power
- Minimum size of particles ranging from 0.2-0.4
- Power to mix freely
- Good chemical resistance
- Acceptable levels of hardness, brilliance and stability on printed and dyed goods
- Good resistance to light, wetness and abrasion
- Chemical inertness
- Excellent dispersion
Depending upon their toxicity, heat stability, staining, tinting strength, opacity and dispersion they become suitable for different applications.
Colorful World of Pigments
In the above classes of pigments lie different shades that give the marvelous chrome paint look or the deep rich hues or bright splashes of color that is needed for various applications. You have several hues like pigment green, pigment blue, pigment red, pigment yellow and many more in each of the categories.
If one has to go into the history of each of these shades, it will make for some very interesting read. The first known blue pigment is supposed to be the naturally occurring mineral azurite which was followed by Egyptian blue and then the expensive ultramarine. As far as red goes, the first used red pigment was red ochre and in case of the pigment yellow it was the yellow ochre. Pigment green was made since Antiquity by mixing blue and yellow. Today, however, due to vast advances in chemistry several shades of these pigments are available for use by mankind.
