Guitar Body Cracks
Source:Crack & Brace Repair
Top Open Aligned Crack Repair:
As with Hairline Crack Repair, Open Cracks in spruce tops are some of the most difficult cracks to repair. The reason for this is because of the light wood. Most of the glues that are available today dry with an amber or yellowish color and this shows up immediately on a light Spruce Top.
If the wood has darkened with age, you are lucky and you can use either Titebond or a 2-part epoxy glue for these cracks. If not – you should stick with a bottled hide glue, which drys to a much clearer appearance.
If you have determined that the crack edges are still aligned, please proceed. If they are miss-aligned you will have to follow the directions in the article Top Open Miss-Aligned Crack Repair.
Cutting Through The Crack:
Try to have different gauged saw blades in stock so you can use one of the proper thickness to saw out the crack. These can vary from about .010″ to .030″ in thickness.
When you have selected a blade that will shave just a whisker of wood off each side of the crack, saw through the top the entire length of the crack. Be sure to navigate around any top braces you may encounter.
When you approach the ends of the crack, leave a ramp in the cut by angling the blade at 45 to 60 degrees.
Preparing the Splint:
This is where it is good practice to have a variety of wood around your shop for different repair tasks. You should search for a piece of top wood that as nearly matches the guitar you are repairing, both in color and thickness.
Once you have done that, take a very sharp marking knife or X-Acto knife and slice a piece of top wood from the new top wood. Make the cut through the soft or light colored portion of the top wood.
Your goal here is to get a piece of the darker hard-grain of the top wood, along with the light softwood on either side of the splint. It also should be slightly longer than the clean-out crack and slightly thicker than the top wood you are repairing. Don’t be too disappointed if you have to try this several times before you get it right. Different woods act differently and you have to get just the right combination of grain and technique to pull it off.
If you can’t get the splint to split cleanly, try cutting in the opposite direction. If you still don’t have success, try a different piece of wood.
Size the Splint:
You now have to clean some of the soft grain from the splint. You can do this with a sanding stick or a very sharp chisel, by laying the splint on its side and making smooth long strokes. Then, do this to the opposite side of the splint. I try to taper the splint just a bit too, by angling the sanding stick. Cut the ends of the splint to match the angle you place on the cut ends of the crack.
Try to insert the splint in the crack to see if any additional sizing will be required. Your goal for fitting is to have a snug fit, but not one that will take a lot of force to insert the piece because remember, we still have to apply the glue.
Glue the Splint:
Start by preparing the crack for gluing. Put a strip of painters tape on either side of the crack – about 1/32″ from the edge of the crack. Work glue into the crack with a artists spatula or your index finger. Coat both sides of the splint with glue as well. Work the splint into the crack, starting on one end and press firmly into place. Let dry overnight.
Glue Cleanup:
Clean off the bottom of the crack area with fine sandpaper. Remove the tape from the top and carefully cut the top of the splint down to the top surface. If a bit of refinishing is in order, scrape the top of the splint to below the guitar top finish, along with some of the guitar top varnish or lacquer. We will then feather the finish of the splint area with the existing guitar finish area.
Apply Patch Reinforcements:
This was covered the the Top Hairline Crack Article and you should read the detailed directions there for the procedure. Be sure not to space your patches out more than about 1-1/2″ to 2″ to provide adequate top reinforcement.
Finishing:
We will cover the proper way to finish the crack repair area in the article Finishing Crack Repairs, since there are so many different kinds of cracks to address.
Tags: closed guitar crack repair, fixing cracks, guitar top crack repair, guitar top hairline crack repair, how to fix a guitar crack
