Single-coat, single-layer paint (Fig. 1): Today, this technique is only found in older vehicles (for instance, oldtimers) that were predominantly solid-coloured vehicles. Single-coat paints are nowadays extremely rare because all car paints today are water-based. This water-based paint is relatively soft and therefore has to be coated again with a second clear and transparent topcoat. This is the so-called two-coat, solid-coloured paint  (Fig. 2). When using a rubbing compound, single-coat paintwork can be identified easily because the polishing pad will immediately take on the colour of the car. Two-coat metallic paint (Fig. 3): All modern paint systems are based on two-layer paints. Water-based paint systems require a clear coat in order to give the surface in question its decisive quality characteristics. In particular, it is this clear coat that gives the metallic paint its metallic effect and gloss. Without it, the surface would be matt and dull. The actual polishing of the paint to remove weathering or to create a gloss thus occurs exclusively on the clear coat. In contrast to single-coat, solid-coloured paints, the difference – when treating two-coat metallic paints (Fig. 3) with a rubbing compound by machine – is clearly visible because the polishing pad will not take on the colour of the car.