Article: He dropped his guitar! Step-by-step repair photos
Here is a step-by-step view of a recent repair on a cedar-faced Breedlove guitar. The guitar received a blow on the side where the top and side meet. This caused the top to loosen from the side and pop up. The photos show that lacquer was fractured and chipped and a splinter of cedar was knocked off.
First, the structural repair was done with woodworking glue. After I determined that no braces were knocked loose from the face, I worked glue into the cracks until it began to show complete penetration inside the guitar.
The damaged area was clamped in alignment with the surrounding wood using a plexiglas caul. I made these spool clamps about 30 years ago from wooden spools my Mom donated. I have threaded rod in several lengths for different jobs.
The next day, the clamps were removed and all visible glue washed off with warm water. This really completes the structural repair; the rest is cosmetic. In the olden days, we might have used "burn-in stick" (also called shellac stick) to fill the area where wood was missing. (You can see in the first pictures that a toothpick's worth of cedar is missing.) The resulting repair would look, at best, good from some angles and bad from others. A larger missing piece would call for an inlay of matching wood, but for this case the best approach was to fill the area and replace the chipped lacquer with cyano-acrylate adhesive (CA, known by the brand name Super Glue). I used three thin applications, with accelerator wiped on to make sure the CA dried rock hard. Looks pretty ugly at this point!
Here's what it looked like after wet-sanding with 1200 grit sandpaper. It's just about ready for buffing. CA will buff out just as shiny as lacquer, so you don't usually have to overcoat it. It's harder than lacquer, though, so you have to be careful not to sand through the surrounding finish when you're leveling a repair like this.
Here are two views of the finished repair. The area of missing wood appears slightly darker than the surrounding cedar because of the relatively thick clear coat over it. You can see in the reflection of the overhead light that the surface appears continuous. It's not invisible, but you have to get your nose right on it to see the repair. I thought this turned out as well as it possibly could, and our customer was quite pleased.