All paints, coatings, and inks use pigments, making the an essential component for the industry. On a basic level they give paints and coatings colour, bulk, or a desired physical and chemical quality.
What gives pigment its colour?
It is all about the chemical structure - the selective absorption and reflection of various wavelengths of light at the pigment's surface. All coloured pigments absorb a portion of all light wavelengths, whilst almost all light is absorbed by black pigments and white pigments reflect almost all visible light.
Colour Strength
When choosing pigments, consider the colour strength or, as it is also know the tinctorial strength. When a coloured pigment is combined with another pigment, its colour strength refers to how well it retains its original colour therefore the less pigment required to obtain a typical depth of shade, the higher the colour strength.
Chemical Structure
One of the factors that affect a pigment's colour strength is its chemical structure. This is because the colour strength of organic pigments is determined by their ability to absorb specific wavelengths of light.
Particle size also has an impact on colour strength. The smaller the particle the greater the colour strength is increased. Colour strength is also influenced by effective pigment dispersion.
Heat Resistance
It is well known that pigments become more soluble at higher temperatures, and discolouration can occur. Inorganic pigments are more heat stable than organic pigments, with the exception of yellow iron oxide, which loses water from the crystal at high temperatures.
Weather Stability
Colour pigments should be chosen for outdoor applications based on their weather resistance qualities. The selection of pigments for outdoor application is influenced by the following factors:
· Required outdoor performance (lifetime and climate to be taken into account)
· Binder type
· The concentration of the pigment
· Presence of titanium dioxide (which typically accelerates fading)
· Concentration and type of light stabilisers used
· The surface of the painted object can affect performance
If you are looking for pigments or need information on what pigments to use for your particular application contact Chemgrit Coatings on www.chemgritsa.co.za or nade@chemgritsa.co.za.