Repairing ff-Hole Cracks in Violin Family Instruments

F-hole cracks are some of the most common cracks found on violin family instruments, but no two ever behave quite the same. They can range from tight hairline wing cracks to wider separations that require more creative clamping and reinforcement. Because of the shape of the f-hole and the limited access through it, each repair tends to require a slightly different approach to achieve proper alignment and support. The examples below show a variety of real-world situations and the different methods used to bring the cracks back together cleanly while preserving both the structure and the appearance of the instrument.

Violin ff crack

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A bad cello ff crack.

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Here are a bunch of various ff clampng methods.

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FF Hole Cracks are very common for violin family instruments. Most of the time they can be glued from the outside. If the instrument is taken apart a well fitted cleat can be added to help strengthen that area.

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Another "ff" crack. Each one needs to be glued using a silghtly different technique.

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This repair shows how a more open f-hole crack can be pulled back together and reinforced without removing the top. When the crack is wider, simply gluing it is not enough—the joint needs to be carefully aligned, compressed, and supported from the inside. By using a combination of controlled clamping from the outside and a reinforcing fiber strip placed through the f-hole, the crack can be brought back together securely. The process requires planning the clamp angles and working within the limited access of the f-hole, but it allows for a strong, clean repair while keeping the instrument fully assembled.

• Clean the crack: Make sure the crack is free of dirt and debris so the glue can penetrate properly.
• Align the crack: Use a small roll of leather as a wedge to bring the crack together, allowing fine vertical adjustment while clamping.
• Apply additional clamping: Because this crack was fairly open, a second clamp was used to help pull the joint fully together.
• Prepare internal reinforcement: Cut a wide strip of fiber to reinforce the crack from the inside. The size is limited by the f-hole opening and clamp positioning.
• Plan clamp placement: Position the fiber strip on the outside of the instrument and determine the correct clamp angle needed to reach it through the f-hole.
• Mark the clamp angle: Mark the angle so the clamp can be guided accurately during installation.
• Hydrate the fiber strip: Soak the strip lightly with water to make it more flexible.
• Attach strip to clamp: Use a small drop of CA glue on the end of the clamp to temporarily hold the fiber strip in position.
• Apply wood glue: Coat the fiber strip with glue for the permanent bond.
• Install the reinforcement: Feed the clamp and fiber strip through the f-hole and position it over the crack, then tighten the clamp.
• Add secondary clamp: Use a second clamp as needed to ensure even pressure along the length of the strip.
• Allow to cure: Let the repair sit for about 24 hours.
• Remove the clamp: Gently wiggle the clamp to release it from the fiber strip.
• Seal the crack: Apply a clear finish to seal the crack and prevent dirt from collecting during future cleaning and polishing.

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