Prepare the surfaces to be mated using either of the following procedures. For smooth surfaces of molded form joints, roughen the surface with a rasp then break the skin of the foam using either end of of a hammer to make dents. On cut foam surfaces, dust off the form with a brush or compressed air.

Long drywall screws or nails must be used to immobilize the joint during the cure period. Start them in at this time to allow one-handed hammering or screw drill-driving later.

Apply a thin coating of Bondo to each surface to be joined, pressing it firmly into the cells of the foam. Cover the entire surface, but remember that a thick coat is no stronger, and will be difficult to work with when the parts are joined.

Press the sections firmly together, being careful to bring them into proper alignment. Screw in the drywall screws or set the nails to hold the sections in place until the Bondo sets. Clean up any excess Bondo. Allow three hours for the Bondo to cure. Do not put any pressure on the joint during this period.

For large life-size or shoulder forms, especially those that require shipping your may want additional reinforcement. Sharpen on end of several threaded rods. Using an electric drill, run two or three rods through the form and bonded joint at different angles. Cut off the protruding rod. Do not hammer it into the form.

By following this procedure, you can rejoin form parts and expect the result to be just as strong or stronger than the original form.