A dye dissolves, or is absorbed molecule by molecule, into the material it colours. A pigment is an insoluble particle that stays a particle and is held in place by a binder, resin or polymer.
That one difference decides how each is made, tested, used and specified.
Side by side
- Dyes colour textiles, paper and leather by entering the fibre; pigments colour paints, inks, plastics and coatings by sitting in a matrix.
- Dyes are judged on strength, shade and fastness on the substrate; pigments are judged on strength, shade, dispersion, heat stability and weather resistance.
- Dye quality depends on purity and standardisation; pigment quality also depends on particle size and surface treatment.
- Dyes are usually transparent; pigments can be transparent or opaque depending on particle size.
Where the line blurs
Pigments can be used on textiles through pigment printing and pigment dyeing, where a binder holds them on the fibre surface. Some dyes, such as vat dyes, become pigment-like inside the fibre. Some pigments are made from dyes by forming an insoluble salt, called a lake.
The Colour Index lists dyes and pigments separately, with names such as C.I. Reactive Blue 19 or C.I. Pigment Blue 15. Read what the colour index number means.
Why this matters for buying
Your specification must test the right things. For a dye, ask for strength against a standard, shade and fastness. For a pigment, ask for strength, shade, dispersion quality and, for plastics, heat stability. A COA that suits one will not suit the other.
Compliance differs too. Dyes on textiles and leather come under banned-amine rules and textile restricted lists. Pigments in toys, food packaging and cosmetics come under separate rules on heavy metals and impurities. Tell your supplier the end use, because the same colour may need a different grade or a different test.
Packing and storage also differ. Dyes, especially reactive dyes, absorb moisture and can lose strength. Pigments are more stable, but fine powders can cake and dust, and pigment presscakes and pastes can dry out or freeze.
Organic and inorganic pigments
Pigments split into two families. Organic pigments, such as phthalocyanine blues and greens, azo yellows and reds, and quinacridones, give bright, strong colours. Inorganic pigments, such as titanium dioxide, iron oxides and carbon black, give opacity, weather resistance and lower cost per unit of hiding.
Gujarat is a strong source of organic pigments, especially phthalocyanines and azo pigments, because they draw on the same intermediates as the dye industry. Read what organic pigments are used for.
Next step
We source both dyes and pigments from Gujarat. We find and audit makers, check samples and documents against your end use, and have lots tested before loading. To start, book a free sourcing review.