TIME TO COLOUR

This is the area of the paint shop where the real magic happens and here the temperature is controlled to between 24 and 27 °C, and humidity at 60 to 65%. The body passes through a feather-dust station to clear the surface before the first base coat of paint is sprayed on.

Interestingly, BMW is implementing a new integrated paint process that eliminates the need for a primer paint station, as this function is fulfilled by the modern base coats. These coats give the vehicle its final colour and, depending on the hue selected, up to three coats are needed to get the desired result (especially in the case of metallic paints).

The application takes place in an airtight room where robots, equipped with extremely expensive, state-ofthe-art nozzles, spray the body. This process sees the vehicle body electrically grounded while the nozzles charge the paint spray using 48 000 V protrusions. This produces a magnetic attraction force between the paint particles and body that fixes the paint to the body. This also helps minimise wastage (overspray) and the rest of the water-based paint particles are forced to the paint shop floor by a downdraft, where it is absorbed by water. This is called a wet-floor arrangement.

The body now spends 20 minutes at 80 °C in another oven that bakes the base coats. It then travels to the clear-coat application room, where the solvent-based clear coat is applied. This layer also acts as the paint’s protective layer and prevents the base coats being damaged by chemicals or light scratches.

A last oven phase cures the clear coat at 170 °C.