Additives Influencing the Quality and Printability of the Paper Surface : Tinting (Shading)
In many cases, the yellowish color of the coating clay does not satisfy market requirements. Apart from the addition of pigments such as titanium dioxide, which increase brightness, blue-violet dyes (shading dyes ) are often used at a con¬centration of about 2 g per 100 kg of pigment to attain a bluish white coating surface which appears brighter to the eye. Not only basic dyes, but also consider¬ably more lightfast direct dyes and pigments may be used. If the brightness re¬quired is very high, optical brighteners are also added.