Functions of pigments in surface pretreatment:

But why are pigments needed at all for primer systems that are anyway provided with a topcoat subsequently? There are several important reasons.

For manufacturers of coating systems, it is important, for example, that customers work consistently with the manufacturer's system in order to avoid complaints due to incompatibilities with third-party products. Pigments can help to provide the primer layers with an appropriate colour coding and marking so that it can be easily recognised as the manufacturer's coating system in the event of a complaint.

Preparation for a perfect final result

But also the opacity and colour of the final product can be significantly prepared and supported already in the primer layers.

UV stability and the closest colour accuracy, however, often play a subordinate role in such systems. Thus, in the case of titanium dioxide, iron oxide or other coloured pigments, for example, somewhat cheaper, less narrowly specified qualities are often used in order to take into account the corresponding cost pressure. Nevertheless, the necessary quantity of a lower-priced pigment should always be taken into account in comparison with a higher-quality pigment that is perhaps better suited to the system in question.

Did you know, for example, that anatase titanium dioxide pigments have an opacity that is about 20% lower than that of sulphate or chloride types produced in a rutile process? Then, of course, the quantity of these pigments has to be increased accordingly to achieve a similar result.