PIGMENTS IN COLOR – USES AND ADVANTAGES
The world around us is a riot of colors – some dark, some light, some pale, some bright, but each material around us has a color of its own. Apart from the colors in nature, we add colors to every material that is manufactured by man or machine and the color gives the material its distinct personality.
COLORANTS GIVE COLOR TO MATERIALS
Colorants may be dyes or pigments. Though both dyes and pigments provide color, there are significant differences between the two. Dyes are water-soluble and have the texture of fine powder while pigments are insoluble in water and have a coarser texture with bigger particle sizes. Pigments also have an opaque look and light does not pass through it easily unlike dyes that are more translucent.
The purposes for which dyes and pigments are used are also different from each other. Dyes are used in paper-making and textile industries where the lightfastness of color do not have a high significance. On the other hand, pigments provide more lightfast coloring and are used in a wide variety of industries like plastic, coatings, paints, printing inks, cosmetics, fabric-making, food industry, and many others.
HISTORY OF PIGMENTS
Pigments have probably been in use from as early as humans had evolved. Even before other forms of communication were thought of, early man used pictures on walls of caves to communicate his ideas with others. Starting from the ochre of natural clay, man evolved to the use of charcoal and various minerals in his quest to find natural colors. He then discovered that natural colorants blended well with each other and created secondary colors that are in use even today.
The introduction of synthetic pigments made with the use of extensive research into chemicals, methods of drawing out mineral colorants, and modern technology, pigment manufacturers have now started creating and producing colors that can withstand tough conditions, have more impact, and last longer.
INDUSTRIAL USE OF PIGMENTS
There are a multitude of pigments in the market today. For the sake of standardization, pigments are referred to with codes like pigment po5, pr122 pigment, pigment py3, etc. Broadly, pigments are classified into two in the modern color industry
- Organic Colorants – These pigments are obtained from natural sources like minerals and plants. They go through a process of cleansing, drying, granulating, and amalgamation into a formula used as a colorant.
- Inorganic Colorants – Also known as synthetic pigments, these pigments are obtained from coal tars and some form of petrochemicals and formulated in laboratories. This is the most common form of colorants being used for industrial purposes now.
DIFFERENCES BETWEEN ORGANIC AND INORGANIC PIGMENTS
The most common differences between the organic and inorganic colorants are in:
- Weight – Organic colorants have more volume but the inorganic colorants are heavier in weight due to the presence of minerals in them.
- Particle Size – Organic colorants have a smaller particle size in comparison to inorganic colorants making them more transparent than synthetic pigments.
- Lightfastness – Inorganic colorants have more resistance and hold their color better than organic colorants.
- Cost – Organic colorants have a higher production cost and are much more expensive in bulk quantities than inorganic colorants.