What happens when you try to paint your carefully built Styrofoam city model with a spray paint that contains solvents? Actually, a lot! - one example being, unfortunately, that the solvent will eat out large craters in your foam. In order to avoid such an eventuality you have to be particularly careful when choosing your paint (see: MARABU SPRAY PAINT) and maintain the proper distance when spraying or, alternatively, you can employ a polystyrene primer beforehand. This will provide the Styrofoam (which was cut by means of a hot wire!) with a once again smoothed out and matte surface. After applying between 2 and 3 coats of this primer you can then use most synthetic resin and acrylic paints for colouring purposes without having to worry about compatibility issues. We have tested MARABU SPRAY PAINTs, AERODECOR SPRAY PAINTs and Dupli-Color paints in this regard and found that they work wonderfully – if you are using other types of paint we recommend a preliminary test.

The surface of the rigid foam you want to paint should be closed-pore and as smooth as possible; like, for example, the way the surface turns out when being worked on with a POLYSTYRENE CUTTER. This is highly recommended because this primer when applied is very thin and not able to correct for unevenness or fill holes. This primer is therefore not suitable for use on an untreated and porous polystyrene surface with the deep “craters” between the cut foam granules that often result from cutting work on such material. Priming courser rigid foam surfaces does indeed lead to a much better acceptance of paint but will not produce a satisfactory result.

One can (150 ml) of primer is enough to cover an area of about 0.2 to 0.3 m².