Clean with acetone first, sand with 80 grit or coarser, then wipe the dust
off. THicken the epoxy as needed with colloidal silica, milled glass or
other structural filler. Don't over-clamp.

bruce wrote:

What is the correct/best method to glue together two surfaces of made
from polyester resin with epoxy glue? This is a structural bond not a
cosmetic one.
Will roughing up the surfaces with 180-grid sandpaper and then
cleaning with acetone be ok or do I need to do more than this.