Please can some of you experienced modellers answer a newbie question?
I am making some scenery out of polystyrene packing material, the sort you get holding a new video in the box. I have shaped it to the correct shape - lots of mess, but now I want to paint it to stop the bits falling off etc. Do I first coat it in a 50:50 mix of water/PVA glue and then paint or do I need to put some form of filler on first, the sort of thing you fill the cracks in walls with?