Pigment is a substance that can absorb light and reflect some lights to show color but it is water insoluble substance. Normally it is used for printing (with the presence of binder) or mas-coloration of the synthetic fibres.
Properties of Pigments
- Chemically inert
- Resistance to acid
- Resistance to solvent
- Pigments have suitable brilliance, hardness and stability
- Good wet, light and moderate abrasion resistance
Classification of Pigments
- Inorganic Pigments
- Organic Pigments
Inorganic Pigments:
- Heaviness in weight (because of the mineral content)
- Large particles
- Good wetting properties (because the particles don’t float)
- Leanness (which gives their colors a matte look)
- Low tinting strength
- Mass tones that gray down when mixed with white (creating more natural light effects)
- Light-to-dark shift within a family
- High lightfast rating
Exceptions include Prussian blue and viridian—both are inorganic pigments that have high tinting strengths and small particle sizes.
Organic pigments:
- Lightness in weight (creating high volume)
- Small particle size
- Resistance to wetting (because the particles float and, therefore, need a dispersion agent)
- Fatness (giving them a natural gloss)
- Transparency or semi-transparency
- High tinting strength
- Mass tones that create intense tints when mixed with white (causing them to stay high key unless a complement is added, and creating less-natural light effects)
- Warm-to-cool shift within a family
- Good-to-excellent lightfast ratings
Exceptions are some of the historic organic pigments—such as rose madder and carmine—which have poor lightfast ratings and are prone to fading.
Advantages of using pigments in textile application
- Pigments can be applied to all type of fibres by using suitable binder even to synthetic fibres, their blends and glass fibres which is difficult to color by other dyeing technique.
- No washing is required, so drying and curing is simple.
- Extensive color range with high color fastness.
- No after-treatment is required in pigment printing, whereas it is essential and complex task in dye printing.
Disadvantages of using pigments in textile application
- The quality of dyeing or printing depends on the characteristics of binder used to affix the pigment with the substrate. The chemical and physical properties of binder influences the performance of pigment dyed fabric.
- Adverse effect due to binder as it changes the texture of the fabric as well as lower the rubbing fastness.
- Some solvent used in pigment emulsion like kerosene, white-spirit causes flammability or pollution problems.
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