Today, there has been a revolution in the plastic industry with so many beautifully coloured hues of products being made available by the manufacturers. A wide choice is available in the shades and forms as you have products available in several tints such as pigment blue, pigment orange, pigment yellow or any other colour shade. These pigments have definitely made the world of plastics a visual treat to the eyes!
The journey of these pigment powders is a long one. From being used by early man on cave walls in the form of earth pigments, today pigments have become an indispensable part of several industries with the plastic industry being one of the major ones. The earlier colours used were obtained from natural dyes, for example, from tree barks, indigo, leaves etc. However, in today’s times, several synthetic dyes available in a wide colour range enhance the beauty of the output from the plastic industry. So, you have pigment red, pigment orange, pigment blue and pigment yellow all working their way into the manufacturing process at some point or the other.
How did these pigments originate? The earlier pigments were introduced to the world by the Chinese and the Egyptians. Earth colours, mineral based pigments and Egyptian blue were among the first of the pigments that were predominantly used. The ‘lake’ making process of manufacturing pigments was also developed by the Egyptians and the basic method is being used for producing certain pigments even today. Several experimental techniques were adopted during the Renaissance period to create several beautiful pigment hues. However, the first accidentally laboratory developed synthesized colour was pigment blue, specifically named Prussian blue. This was followed by the French Ultramarine, then Chrome Yellow and Zinc Oxide. The most significant organic pigment that was developed in the laboratory was undoubtedly Alizarin. This was a low cost synthetic alternative which became very popular in the 19th century. Later on rapid strides in technology, revolution in the transport system brought about a revolution in the world of pigments.
How do we understand that a certain pigment is pigment blue or pigment yellow or pigment orange? The colour of a pigment is seen due to its characteristic of absorbing certain wavelengths of light. Different pigments absorb different wavelengths and depending upon what is absorbed, a specific colour is reflected which is seen by the eye. A pigment that absorbs light of all wavelengths reflects the colour black whereas pigment yellow or pigment blue is seen as such because pigments absorb wavelengths corresponding to that colour. The reflected light is deemed to be the colour of the pigment.
Today, there is a greater tendency of using pigments that are environment friendly and less toxic in the plastic industry. This has led to the elimination of lead chromate pigments from being used in the consumer plastics and its replacement by the organic yellow pigments having superior tint capacities in polyethylene and PVC. There are many other better colorants that have been introduced in the world of plastics. Truly, the contribution of pigments to this world is highly laudable!