The more surface area you have to apply adhesives to, the stronger the bond between the surfaces will be. The surface area of anything you wish to bond is easily increased by ‘roughing’ or ‘scuffing’ the surface. The illustration shows how when a straight line is roughed, more surface area becomes available for the adhesive — thus a better bond between the surfaces. Use different things to rough different items. 80-100 grit sandpaper is great for many things, including PVC, wood and some metals. Other roughing tools include metal files, wire brushes, emery cloth and steel wheels attached to a drill. Be sure to remove any dust that accumulated during the roughing — BEFORE applying your adhesive. Finally, use an appropriate de-greaser when necessary, such as on metals. Acetone and denatured alcohol are both superb de-greasers.