The roughness is unfortunately part of the model, rather than something that has just stuck to the surface.
On some models I've got rid of the worst of it with a bit of wet-n-dry paper, on others it's been in inaccessible places and beyond fixing. I always give the models a coat of gloss varnish as well before putting in the moulds, which helps to further soften down the effect (and helps free the model from the mould).
Last edited: Aug 29, 2012