This cello came into the shop with a section of one back corner missing, leaving a cosmetic challenge. Since the opposite side of the instrument was still intact, it provided an excellent pattern for recreating the original shape. A custom mold was made using Styrofoam and a traced template so the missing section could be cast to match the existing rib. After the new piece cured, it was carefully shaped, fitted, and blended into the surrounding wood before receiving touch-up varnish. The following steps outline the process used to rebuild the missing rib and restore the violin's original outline. This repair also demonstrates a newer technique that I developed for restoring damaged edges and corners on student-grade instruments. The method uses a repair material of my own formulation that was designed specifically for these types of repairs. It is exceptionally strong, closely resembles wood, and can be filed, sanded, carved, and touch-up varnished much like the original material. Combined with a custom mold, it provides a durable repair that closely restores the instrument's original shape and appearance. - Create a Template – Trace the opposite side of the cello to capture the original outline and use it as a guide for rebuilding the missing section.
- Cut the Styrofoam Form – Shape a piece of Styrofoam to create the foundation for the repair mold.
- Fit the Rib Support – Make a small Styrofoam piece that follows the contour of the cello rib.
- Protect the Original Rib – Apply painter's tape to the rib so the temporary mold can be removed cleanly.
- Attach the Rib Form – Glue the shaped Styrofoam support to the painter's tape.
- Complete the Mold – Fit the upper template piece and glue it to the rib support, creating the cavity for the missing section.
- Build a Back Dam – Install a small dam across the back of the mold to contain the casting material.
- Prepare the Repair Material – Mix the casting material thoroughly before pouring.
- Cast the Missing Section – Carefully pour the material into the mold and allow it to cure overnight.
- Remove the Mold – The following day, remove the Styrofoam form to reveal the newly cast repair.
- Shape the Repair – File and refine the new section, using the template as a guide until it matches the original outline.
- Apply Touch-Up Varnish – Blend the repair into the surrounding finish with carefully matched touch-up varnish.
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