A melter for preparing a molten medium, in particular for preparing a molten adhesive, has a housing and a melting tank formed within the housing. The melter further has a filling opening for introducing the medium to be melted. The melter further has a wall section which encircles the filling opening. The melter further has an insulating body which encircles the filling opening and covers the wall section. The insulating body is elastically deformable for use in such a melter.