Epiphone Cortez Repair Blog #3: Scrapers, glues and bagging

Bagging

The last thing I’ll talk about this time is rehydrating a guitar through the use of the bagging technique. If a guitar is dry, any cracks will open up and become very difficult to glue back together. There are other problems caused by dry guitars–sunken top, fretboard hump, sharp fret ends, weird neck angle–but they all come back to the same thing: wood shrinkage. What bagging will hopefully do for us in this case is close up the wider cracks. When they’re tight we can glue them and expect good results.

This is the bag (it’s being hung out to dry). You get a couple of strong bags and tape them together. You could use one bag, but it has to big enough to cover the whole guitar while leaving space at the bottom.

 

The first thing that goes into the bag is a big, damp bath sponge (pictured). This sits at the bottom of the bag. It’s important that we minimise excessive water. We don’t want a pool at the bottom or the inside of the bag to be sopping wet.

Next, the guitar goes into the bag. It never touches the sponge. It never touches the bottom of the bag. We don’t want a guitar sitting in a puddle for 3 days. That would be bad.

The bag is then secured at the top. This is the elastic from an old dust-mask which is easy to cinch tight. But you can use anything: elastic bands or whatever as long as it’s fairly air tight. The other thing I like to use is latex surgical tubing which you can make nice and tight and has a bunch of other uses around the workshop.
The bagged guitar then gets hung up out the way for no more than 3 or 4 days. Check periodically to make sure nothing weird’s happening in there. It’s also important to make sure your workshop isn’t too dry. Get a hygrometer. Try to keep the environment around 50% humidity.

So, the Cortez went into the bag for a few days, and when it came out, the few wide cracks had closed up and we were able to proceed with gluing. I’ll go through that next time, how we use rare earth magnets, and the process of making a new, accurate bridge. See you then!

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