Official Luthiers Forum!

Hello! I haven't been posting or building for about 5 years. I'm about to start building again - I am so excited!
But before that, I have a friend in need. His favorite guitar is a 1962 Gibson. The back seam opened up. The back braces were also coming off. I pulled the braces off and sanded the braces and back to remove the adhesive. I can easily reattach them.
The back seam is another issue. I don't think I can sand off the adhesive. It is reddish-brown in color. Does anyone know what the adhesive is the Gibson used back then on their LG0 guitars? Does the color provide enough information? I'm hoping that it is HHG. Is there a way to determine if it is?
If I cannot determine what it is, I might use epoxy, unless someone has a better idea.
Would opening it up to about .025" so I can remove the adhesive and add a thin purfling work well?
I'm open to ideas. This is a free fix for a friend, but I want it to work out great.
Thanks!

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"An adventure is only an inconvenience rightly considered. An inconvenience is an adventure wrongly considered." G. K. Chesterton.

Pics would help.

Being a 62 Gibby it should be put together with aliphatic glue., But also being 1962 the possibility exists this was repaired before and may be something else.... Whatever you do, please do not use epoxy! You will make any farther repairs impossible and may wind up with a mess from attempting to glue up that ruins the instrument. Being an instrument that is sort of valuable and that it may become more collectible with time maybe you should pass this on to someone more qualified?

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Brian

You never know what you are capable of until you actually try.

https://www.howardguitarsdelaware.com/

Thanks, Brian. - No epoxy. Sorry - I do not have pictures.
My friend likes to leave his guitar out and it is suffering from drying out. I think I have convinced him to humidify his music room - doesn't want to keep it in the case.

Do you think it would be a bad idea to put in a mahogany back seam?

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"An adventure is only an inconvenience rightly considered. An inconvenience is an adventure wrongly considered." G. K. Chesterton.

To find out if it is HHG add water. Don't drench it but rubbing a wet paper towel over it should soften it enough to remove it if it is HHG. The water may also help close up the crack. To remove it you could also try vinegar or goo gone both of which have acetic acid and work on a number of glues.
If the crack closes up after adding water I would consider adding a back graft to reinforce the seam. If it doesn't close up then adding a "purfling splint" and a back graft might work O.K.
Keeping things original is the usually the best course of action (says the guy who has transmogrified a number of instruments in the past), but sometimes you need to make slight modifications to keep an instrument together and playable.

The opening up between plates could just be geometry....Once the back braces popped and no longer hold the plates at the correct radius a crack will open to allow the plates to change shape. Sometimes just getting them back down to the braces will close the gap.... and with the braces being out they could easily be flattened slightly to bring together any gaps remaining.

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Brian

You never know what you are capable of until you actually try.

https://www.howardguitarsdelaware.com/

Lots of good advice in here from Brian and Clay.

I've run into the back seam issue more than a few times on these. What I've noticed is that the back on some of the ones in this era are radiused flatter than the braces themselves, so the back braces on these are super prone to popping off constantly. Might be worth your time while you're at it to re-radius them to fit the back better.

Physicians are known to turn patients loose who won't follow doc's instructions. This story ain't too far from that. From my perch, I think this story won't end well. I encourage OP to turn the job away and let a person with a whole lot of experience deal with a customer who abuses his instruments.

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Peter Havriluk

The red glue is most likely Resorcinol. Gibson used this glue for a few years, and I believe your friend's '62 falls in this era. Resorcinol is totally waterproof and was used in wooden boat building (and is crazy toxic). Who made the decision at Gibson to use this glue would be an interesting tidbit.
Nashville Soundcheck flooded in 2010 and many instruments were lost. I heard Raúl Malo on the radio recounting finding his prized J-45 completely full of water in the aftermath of the flood. He dumped the water out and hung it on the wall to dry. After a month or two of drying it came back "better than before" according to Malo, with no damage whatsoever.
This anecdote is not meant to advocate Resorcinol for guitars. But, I found the story interesting.
I think you are up against it with trying to repair a surface that is saturated with Resorcinol.
Wish I could offer more advice.

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Stay with the happy people.
--Reynolds Large

I thought the experimental phenolic resin glue was a bit earlier than this but it could be that stuff.

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Brian

You never know what you are capable of until you actually try.

https://www.howardguitarsdelaware.com/

While I do agree typical epoxy is not a good tool on guitars west systems is a very handy tool for the luthier. Pat Diburro turned me on to this a while back. If you can use the typical glues on a clean joint but every once in a while epoxy is the tool you need. On contaminated joints epoxy may be the only viable option.
I especially like the 206 hardener as this allows about a 15 hr cure time for good penetration.

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John Hall
blues creek guitars
Authorized CF Martin Repair
Co President of ASIA
You Don't know what you don't know until you know it