caravan paint?

I assume you mean runs....you can't you have to sand them out using carbody carborundum paper commonly known as 'wet and dry' paper as it can be used dry or wetted with water. Get 1 sheet coarse grade and one sheet of fine. or you can get sanding blocks one side coarse the other fine. Dip in water sand out the runs clean it off and wait for it to dry before re-painting and don't spray too close and apply too much paint that's what causes the runs.
Better about 5 lightly sprayed coats and wait for each to dry before applying the next coat. Lightly rub down each layer with the fine sheet wet then allow to dry except the last layer. Rubbing down each layer will ensure a flat surface if done properly. Spray about 5 or six layers. Don't sand last layer down allow it to dry thoroughly then rube lightly with T cut or silver/copper/brass polish, or use a laquer to protect the surface.

Bob
June 2011