<<On your site you said that they were plaster and paper mache. Will the two materials join?>>
LOL! I THINK so! I'd never tried combining the two materials before, but it did seem to work. They used the papier-mache' over areas of (DRY) plaster gauze. I used a flour and water paste with the papier-mache'.
We mainly used papier-mache' to fill in some gaps in the gauze OR to give a smoother surface on some areas.