What’s Pigment and Its Physical Basis?

A pigment is a material that changes the color of reflected or transmitted light as the result of wavelength-selective absorption. This physical process differs from fluorescence, phosphorescence, and other forms of luminescence, in which a material emits light.

For industrial applications, as well as in the arts, permanence and stability are desirable properties. Pigments that are not permanent are called fugitive. Fugitive pigments fade over time, or with exposure to light, while some eventually blacken.

You don’t just find pigments for paint, but also for coloring ink, plastic, fabric, cosmetics, food, and other materials. Most pigments used in manufacturing and the visual arts are dry colorants, usually ground into a fine powder. This powder is added to a binder (or vehicle), a relatively neutral or colorless material that suspends the pigment and gives the paint its adhesion.

Pigments appear the colors they are because they selectively reflect and absorb certain wavelengths of visible light. White light is a roughly equal mixture of the entire spectrum of visible light with a wavelength in a range from about 375 or 400 nanometers to about 760 or 780 nm. When this light encounters a pigment, parts of the spectrum are absorbed by the molecules or ions of the pigment. In organic pigments such as diazo or phthalocyanine compounds the light is absorbed by the conjugated systems of double bonds in the molecule.

The appearance of pigment for coating is intimately connected to the color of the source light. Sunlight has a high color temperature, and a fairly uniform spectrum, and is considered a standard for white light. Artificial light sources tend to have great peaks in some parts of their spectrum, and deep valleys in others. Viewed under these conditions, pigments will appear different colors.

Naturally occurring pigments such as ochres and iron oxides have been used as colorants since prehistoric times. Archaeologists have uncovered evidence that early humans used paint for aesthetic purposes such as body decoration.

Before the development of synthetic pigments, and the refinement of techniques for extracting mineral pigments, batches of color were often inconsistent. With the development of a modern color industry, manufacturers and professionals have cooperated to create international standards for identifying, producing, measuring, and testing colors.

Selection of a pigment for a particular application is determined by cost, and by the physical properties and attributes of the pigment itself. For example, a pigment that is used to color glass must have very high heat stability in order to survive the manufacturing process; but, suspended in the glass vehicle, its resistance to alkali or acidic materials is not an issue. In artistic paint, heat stability is less important, while lightfastness and toxicity are greater concerns.

Let’s Get Deep Into Industrial Colorants

Colorants are employed in several industries to color garments, plastics, paints, prints, photographs and ceramics. Now colorants are also being employed in new applications and are termed functional as they aren’t just comprised in the product for visual reasons but for particular purposes, for instance in surgery.

Industrial colorants can be either pigments or dyes. Dyes are soluble colored natural elements that are generally employed to fabrics from a solution in water. They’re made to bond powerfully to the polymer molecules that make up the fibre textile.

Pigments are insoluble element employed in ceramics, plastics, printing inks and paints. They’re applied by employing a dispersion in an appropriate medium. A majority of pigments employed are also organic elements.

Throughout the procedure of a dyeing a fabric, the dye is dispersed amid the 2 phases, the aqueous phase and the solid fiber phase, and at the conclusion of the dyeing procedure the solution is exhausted and a majority of the dye is concerned with the textile. As soon as the dye molecules get into the fibre there’s instant interaction amid the 2 elements, which stops desorption of the dye molecules back into solution. This kind of interaction, whether chemical or physical, will rely on the groups on the dye molecules as well as in the fiber chains.

Categorization of industrial colors by procedures of application:

Classification by the method of application is important to the textile dyer applying the dye to produce the color required. To obtain the required shade the dyer usually has to make mixtures of dyes and must ensure that these are compatible.

The basic features that control dye transfer from solution to fibre are:

• the pH of the solution in the dye bath (for acid and basic dyes)

• an electrolyte (a solution of sodium sulfate or chloride)

• the temperature (within the range of ambient to 400 K)

• chemicals, known as dispersing agents, that produce a stable aqueous dispersion of dyes of very low solubility

pigments:

pigments are employed in the tinge of paints, ceramics, plastics and printing inks. They can be employed on a much wider range of materials than dyes because they’re not dependent on water solubility for their application.

The chromophores used in pigments are typically the same as those used in dyes but the pigments are large molecules and don’t have solubilising groups. They contain groups that form intermolecular bonds that assist to decrease solubilities. The larger the molecule, the more solid the pigment.

What’s Pearl Pigment & How It’s Used

Do you know something about the pearl pigment? Maybe you heard of pigment. A pigment is a material that changes the color of reflected or transmitted light as the result of wavelength-selective absorption. What is pearl pigment? It is a kind of inorganic pigment, have some special features: non-metallic, not including the heavy metal, chemical inertia, non-poisonous, safe for the surrounding and human being. You may see many different types of pearl pigments here.

The most common type is the silver white pearl pigment. It is mica powder coated by titanium oxide, and according to lights' many times reflection, it produced pearl luster. If the mica powder's particle size is bigger, the pearl luster will be better, but the coverage will be worse.

Silver white pearl pigment consists mica coated with TiO2. The different coating layer and the different particle size of mica will produce pearlescent pigments with different silver white effect. For TiO2, there are two kinds: one is Rutile, the other is Anatase. So, if asked for high weather resistant it is better to choose Rutile products. For Mica if the particle size is different, the pearlescent effect will be different as well. If the particle size is coarse it has better luster and higher transparency, even produce a shimmer effect. But for the smaller particle size, it has soft luster and strong coverage performance.

In pace with the growth of living condition, people demand to have more luster paint perfect in color for indoor decoration, and pearl luster pigment is the answer. Pearl luster pigment is excellent in dispersion, and good in physical and chemical property. As such, pearl luster pigment is suitable for mixture with any single-color paint to make pearl paint, which not only affect the color result, but also enhance the color expression of paint.

Aqueous pigment dispersions are widely used in different industry. In addition, pearl luster pigment also is suitable for most of both oil-base and water-base paint, especial for see-through materials which can promise you the desirable result. However, when pearl luster pigment makes into a mixture with non-transparent paints, the result of pearl luster may seriously affected. Another thing that should be circled out is never process the pearl luster pigment in grinding machine with high shearing stress to avoid destroy the structure and luster of the pigment.

The products have more than one hundred varieties, widely used in various industries, such as paint, plastic, ink, leather, printing, dyeing, rubber, paper making, master batch, etc, and give their products enthralling outlooks and gentlest luster.