Trade Secrets: Making a partial plaster cast

Some repairs require a plaster cast. However, it is not always necessary to make a cast of the entire plate. Someone recently brought to my shop a violin that had been damaged by a large falling object. Luckily it had only hit the corner, but there were several parallel cracks quite close together, as well as some cross-grain cracks.

After removing the top plate I pushed everything in place as well as I could, but the result was not satisfactory. The cracks were too close together to set clamps successfully, and the cross-grain crack would not settle back smoothly where the piece had torn away from the purfling. I therefore decided to make a partial plaster cast of the top plate. This allows for corrections, and forms the perfect counterpart when it comes to clamping…