Fixing Acoustic Guitar Top Cracks: The Cleat Method

Updated at: 05/06/2025

A cracked guitar top is a disheartening sight for any musician, instantly silencing the instrument and raising concerns about its future. The delicate wood of an acoustic guitar's soundboard is susceptible to damage from temperature fluctuations, humidity changes, or even a clumsy bump. While seemingly catastrophic, many cracks, especially those not extending too deeply or widely, can be successfully repaired at home. One of the most effective and commonly used methods for such repairs involves strategically placed cleats – small pieces of wood glued to reinforce the break and restore structural integrity.

This method, while requiring patience and precision, offers a reliable way to revitalize your beloved guitar. For a comprehensive guide on how to execute the cleat repair method effectively, read on to follow our step-by-step instructions and bring your instrument back to its former glory.

Preparation and Safety Guidelines

Tools Needed
  • Acoustic Guitar
  • Glue (Tight Bond High Glue)
  • Small Bowl
  • Sponge
  • Water
  • Hygrometer
  • Plastic Garbage Bag
  • Plastic Callus
  • Clamp
  • Thin Wood Splint (if crack is larger)
  • Magnetic Viewing Film
  • Plastic Cleat Holder
  • Cleat
  • Tape
  • Hot Water
  • Rag
  • Interior Light
Safety Guidelines
  • This repair requires patience and precision. Rushing the process can worsen the crack.
  • Use the appropriate glue for wood repair (e.g., hide glue or wood glue specifically designed for instrument repair). Incorrect glue can damage the instrument.
  • If you are uncomfortable performing this repair yourself, consult a professional luthier. Improper repair can permanently damage your guitar.

Step-by-Step Instructions

  1. Initial Assessment and Humidification Attempt

    • Assess the crack. If small and fresh, attempt humidification to close it.
    • Place guitar in a plastic bag with a bowl of water and a hygrometer. Monitor humidity. Leave overnight.
    • If humidification fails or the crack is too large, proceed with the cleat method.
    If humidification fails or the crack is too large, proceed with the cleat method.If humidification fails or the crack is too large, proceed with the cleat method.
    Initial Assessment and Humidification Attempt

  2. Crack Preparation and Gluing

    • Gently open the crack using your fingers through the sound hole.
    • Apply glue to the crack from the outside.
    • Clean excess glue.
    • Clamp lightly using a flat callus and wax paper to keep the crack flush.
    Clamp lightly using a flat callus and wax paper to keep the crack flush.Clamp lightly using a flat callus and wax paper to keep the crack flush.Clamp lightly using a flat callus and wax paper to keep the crack flush.Clamp lightly using a flat callus and wax paper to keep the crack flush.
    Crack Preparation and Gluing

  3. Cleat Preparation and Placement

    • Prepare the cleat.
    • Use magnetic viewing film and a cleat holder to precisely position the cleat inside the guitar.
    Use magnetic viewing film and a cleat holder to precisely position the cleat inside the guitar.Use magnetic viewing film and a cleat holder to precisely position the cleat inside the guitar.
    Cleat Preparation and Placement

  4. Cleat Installation and Glue Application

    • Apply glue to the cleat and insert it into the crack, ensuring proper alignment.
    Apply glue to the cleat and insert it into the crack, ensuring proper alignment.
    Cleat Installation and Glue Application

  5. Final Cleanup and Drying

    • Clean excess glue after drying with hot water and a rag.
    • Allow the repair to dry for 24 hours.
    Allow the repair to dry for 24 hours.Allow the repair to dry for 24 hours.
    Final Cleanup and Drying

Read more: DIY Long-Lasting Guitar Humidifier for Your Case (Cheap & Effective)

Tips

  • For small, fresh cracks, humidification might close them before gluing.
  • Use magnetic viewing film and a cleat holder for precise cleat placement.

Common Mistakes to Avoid

1. Using the Wrong Glue

Reason: Incorrect glue type can lead to weak bonds and future cracking. Hide glue is ideal for its reversibility, but modern wood glues can also work well.
Solution: Always use a high-quality wood glue specifically designed for instrument repair, such as hide glue or a good quality aliphatic resin glue.

2. Cleat Too Small or Poorly Positioned

Reason: A cleat that's too small won't provide sufficient support, and incorrect placement can weaken the surrounding wood or cause further stress.
Solution: Ensure the cleat is appropriately sized for the crack and strategically positioned to distribute pressure evenly across the soundboard.

3. Insufficient Clamping Pressure

Reason: Inadequate clamping pressure prevents proper glue adhesion, resulting in a weak repair and potential failure.
Solution: Use sufficient clamps to apply even, firm pressure across the entire surface of the cleat and surrounding area until the glue is fully cured.

FAQs

What type of glue should I use for the cleat repair?
Use a hide glue or a high-quality wood glue specifically designed for instrument repair. These glues are less likely to damage the finish and offer a strong, reversible bond.
How do I choose the right size and type of wood for the cleat?
The cleat should be made from a similar wood species to your guitar's top (if possible, matching the grain direction) and should be slightly larger than the crack itself. It needs to be thin enough to not significantly alter the soundboard's profile.
What if the crack is too large or complex for a simple cleat repair?
For larger or more complex cracks, a simple cleat repair might not suffice. It's best to consult a professional luthier for a more involved repair to prevent further damage or compromise the guitar's sound.