This instrument came into the shop with damage to both a corner and a section of the adjoining edge. Rather than fitting replacement pieces of wood, I used my casting technique to rebuild the missing areas while preserving as much of the original wood as possible. For the corner repair, I first made chipboard templates to establish the correct shape, then constructed a temporary Styrofoam mold attached to protective painter's tape. The missing corner was cast, allowed to harden, and carefully shaped to match the original outline. The damaged edge was then repaired using a similar process, with separate molds shaped to follow the ribs and recreate the proper edge overhang. Once both repairs were completed, the reconstructed areas were carefully shaped, finished, and varnished to blend with the surrounding instrument. The following photographs and repair steps are divided into two sections to illustrate each application of the casting technique. - Trace the Corner: Place a piece of chipboard against the back of the instrument and trace the original corner outline to establish the correct shape for the repair.
- Cut the Template: Carefully cut out the traced corner shape using scissors.
- Mark the Rib Outline: Use dividers to make a series of small pinholes in the chipboard, following the shape of the ribs.
- Make the Rib Template: Transfer the rib outline to a new piece of chipboard and cut it out to create a template for shaping the mold.
- Protect the Ribs: Apply painter's tape to the ribs around the damaged corner to protect the original varnish and provide a surface for attaching the temporary mold.
- Make the Inner Mold: Cut and shape a piece of Styrofoam to follow the contour of the ribs, then glue it to the protective tape.
- Make the Outer Mold: Cut another piece of Styrofoam to match the original corner outline established by the template.
- Assemble the Mold: Glue the outer mold to the first piece of Styrofoam, using rubber bands and other supports as needed to hold everything securely in position.
- Create the Dam: Shape a small dam around the missing corner so the casting material will extend slightly above the original edge, leaving enough material for final shaping.
- Seal the Mold: Fill any small gaps in the mold with wood glue to prevent the casting material from leaking out.
- Cast the Missing Corner: Mix the casting material and carefully pour it into the prepared mold, filling the missing section of the corner.
- Allow the Material to Cure: Leave the casting material undisturbed for approximately 24 hours before removing the mold.
- Remove the Mold: Carefully remove the temporary Styrofoam mold to expose the newly reconstructed corner.
- Shape the Corner: Use a knife and file to remove the excess casting material, gradually shaping the rebuilt corner to match the original outline and surrounding wood.
 IMG 20261010 171837 179 | IMG 20261010 171820 581 | IMG 20261010 172357 577 | IMG 20261010 172631 869 | IMG 20261010 173234 212 | IMG 20261010 173552 952 | IMG 20261010 175655 669 | IMG 20261012 095114 550 | IMG 20261012 093538 206 | IMG 20261012 110140 147 | IMG 20261012 110237 020 | |
- Protect the Varnish: Apply painter's tape around the damaged edge to protect the original varnish and provide a surface for attaching the temporary mold.
- Make the Inner Mold: Cut and shape a piece of Styrofoam to follow the contour of the rib beneath the damaged edge.
- Attach the Inner Mold: Glue the shaped Styrofoam to the protective tape, positioning it securely against the rib.
- Make the Outer Mold: Cut another piece of Styrofoam to follow the original outline of the edge and establish the proper overhang.
- Assemble the Mold: Glue the outer mold to the first piece of Styrofoam, creating a channel that follows the shape of the missing edge.
- Create the Dam: Extend the mold slightly above the top surface to contain the casting material and leave enough excess for final shaping.
- Seal the Mold: Fill any small gaps in the mold with wood glue to prevent the casting material from leaking out.
- Rebuild the Missing Edge: Mix the casting material and carefully fill the prepared channel, allowing it to form the missing section of the edge.
- Remove the Molds: Once the casting material has hardened, carefully remove the temporary Styrofoam molds to expose the reconstructed edge.
- Shape and Finish the Edge: Carefully trim, file, and smooth the new material to restore the original edge contour and overhang. Finish the repair with varnish touch-up to blend the reconstructed area with the surrounding instrument.
IMG 20261012 164044 899 | IMG 20261012 175209 846 | IMG 20261013 093354 403 | IMG 20261013 122119 242 | IMG 20261014 131328 794 | IMG 20261016 124706 689 |
Note: The final two photographs show the completed corner and edge repairs. One of the advantages of using two molds is that they establish a flat surface in the same plane as the original top. When the casting material is poured into the mold, one surface of the repair is already flat and properly aligned with the top, leaving considerably less material to remove during final shaping and finishing. IMG 20261029 154122 681 | IMG 20261029 154134 839 |
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