It's a good idea to paint the entire cowl interior, especially where the honeycomb is. I scuffed the surface with scotchbrite pads and painted it with a thinned West Systems epoxy. When the epoxy had kicked but not fully set (neither sticky nor slippery to the touch), I wiped the area the shielding would go with acetone and applied the material. I doubt I could get it off now. As a last step, I ran a brush with epoxy around the edges of the shielding material to keep oil or fuel from seeping under. All done in less than a day, most of which was spent on other tasks while the epoxy cured.
