12.1 INTRODUCTION

Coatings are materials applied to all manner of surfaces to decorate them and protect them from the environment and other sources of harm. Sometimes they perform special functions such as providing an anti-fouling surface. All that from a film rarely more than a few millimetres thick, and usually only a few tens of microns. What is more, the coating must deliver its benefits with the minimum impact on the health of those exposed to it, or the wider environment.

And cheap too! The world demand for paints of all types in the year 2000 was of the order of 24 million tonnes, and worth approaching 40 billion. (The figures have risen steadily since.) Eighty percent of volume and value was accounted for by Western Europe, North America and the Asia-Pacific region, each taking a roughly equal share. On that basis, the average cost of a kilogram of paint, that might cover 10 m ² of surface, was less than 2.00.

We have seen in Chapters 1 11 how much science and care is devoted to the design of coatings materials to ensure that they meet all the needs of their users. It remains to outline the last, and crucial, stage in the manufacturing of the coating itself, when the liquid (or potentially liquid) material is transformed into a solid film, with all the required properties, adhering tenaciously to the substrate.

The application process is usually carried out by the owner of the objects to be painted,...