Anyone have any ideas what adhesive (preferably gun applied) sticks to exposed gypsum (unpapered plasterboard)? I'm wanting to fix aluminium channel to routed plasterboard. I'm thinking CT1 but would I need to use a primer on the gypsum first - maybe one of the Zinsser primers like BIN or Peel Stop. Screws aren't really an option. The channel is 12mm (w) x 8mm (d) and very light weight.