Wood Glue

• One popular method for repairing cracks is with wood glue. Since wood glue is thick, it will need to be diluted with a small amount of vinegar. Using a household iron, heat the cracked area of the guitar for one or two minutes. Apply a small layer of glue to the crack, wiping off excess glue with a towel. When this layer has dried, apply another layer using the same method, and sand down the excess glue with #1500 sandpaper. Finally, wipe down the sanded bits with a second towel.
  
  

Super Glue

• If wood glue is not available, you can repair your top split with Super Glue. First, heat the glue by placing it in a carafe of hot water. This will serve to thin the glue out so it can easily be applied to the wood. Wipe down the cracked area to ensure it is clean. Drip a small amount of glue over the crack and rapidly tap down with one finger to clear the glue from the surface. Repeat this step until the crack is filled. Allow the glue to dry for several minutes.
  
  

White Glue

• Cracks can also be repaired with ordinary white glue. Wet a rag and rub it over the cracked area. This will moisten the wood and open it up for the glue. Apply the glue to the crack and spread it around with the rag. After you have spread around the glue, the only visible glue should be inside the crack.
  
  

Cleats

• Though many cracks can be repaired without using cleats, sometimes it is helpful to have a cleat to reinforce the crack. Simply put, a cleat is a small piece of wood that is attached to both sides of the crack and holds it together. First follow one of the three gluing options above. Then apply glue to one side of the cleat, and using a clamp on the inside of the guitar, secure the cleat under the cracked area. Clamp the cleat down until it is secure -- it may need to remain clamped for as long as an hour. Remember that using a cleat can compromise the guitar's sound so only use one if the crack is significant.