This cello had one of the most challenging cracks to repair—caused by pressure from the soundpost, which caused the back to bulge slightly. The crack also ran diagonally across the grain, adding to the difficulty of the repair. Here’s the process I used:
Remove the Strings: Loosen and remove the strings to relieve the pressure causing the back to bulge.
Create an Outside Mold: Make a mold of the cello’s back to provide external support during the repair process.
Mark Mold Position: Use painter's tape to mark the exact position of the mold to ensure proper alignment.
Attach the Plate: Secure the outside clamping plate to the top of the cello.
Apply Hide Glue: Carefully work hide glue into the crack, ensuring it penetrates deeply.
Clamp the Back: Use the mold to clamp the back into its original, normal position.
Mark the Crack Ends: Place magnets at both ends of the crack to track its exact path.
Cut a Fiber Patch: Cut an oval-shaped piece of fiber to serve as the reinforcement.
Create an Inside Mold: Make an inside mold using two sheets of flexible plastic.
Prepare the Fiber Patch: Hydrate the fiber and apply glue to one side.
Attach the Inside Mold to the Patch: Secure the inside mold to the fiber patch using a single drop of CA glue.
Insert the Patch: Drop the fiber patch through the f-holes and position it precisely under the crack, ensuring it supports the soundpost area.
Adjust the Soundpost: Use an adjustable soundpost to apply the right amount of pressure on the fiber patch.
Secure with Wedges: Place small wooden wedges around the perimeter of the oval patch for added stability.
Allow to Dry: Let the repair sit and dry for a full 24 hours to ensure a strong bond.
Add Supporting Cleats: Install three cleats along the crack’s outer edges using magnets to guide their placement.
This method provided a solid, reliable repair without taking the cello apart, restoring the cello's back and ensuring the soundpost had proper support without further bulging or cracking.
