Coroplast Back Board (Steps 10, 11 & 19)

10. Measure and cut Coroplast back board.

We aimed to have the Coroplast sheet overlap the frame opening by 1/4 inch.  We positioned the Coroplast and held it in place with weights to drill the holes.

11. Pre‑drill screw holes to attach backboard.

We predrilled holes spaced approximately 3 inches apart. We used a 1/16‑inch bit with a hand drill. This 'overlap' Coroplast backboard protects the pastel from dust and is still easily removable (no adhesive tapes). Also the Coroplast backboard can be attached in the final steps without jarring the pastel. The standard frame sealing method of inserting framers points or brads would cause vibrations damaging to the pastel. We chose Coroplast as a backboard material because it is inert and non‑hydroscopic.

19. Attach Coroplast back board with screws.