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Double Bass What glue for fixing an open seam?

robert_stuart

robert_stuart

Gold Supporting Member
Mar 28, 2017
626
673
Denver
#1
I'm thinking I can tackle this myself: I do occasional furniture repair as a hobby and I have a collection of clamps.

A 7- or 8-inch area on the upper bout back seam has opened up. It's a carved _top_ hybrid. The two pieces that need to be glued are flexible enough that I can press them together with my hands.

My Double Bass guy is pretty busy these days, so I'm thinking of just putting some glue on the joint and clamping it. At the very very worst and I mess it up (I'm not sure how), I'll just bring it in to him.

My questions for you all:

1. Does this look as simple to you all as it does to me? Seems like the easiest kind of fix to DIY.
2. What's the recommended glue for this kind of repair?

Thanks in advance.

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#2
I'm not a luthier, but I've repaired open seams on my ancient student cello that isn't worth anything.

The very outer limit of my luthierie knowledge is that anything but hot hide glue will make it unrepairable in the future. Modern glue undergoes a chemical change as it cures -- polymerization -- that's irreversible. On the other hand, hide glue works by just being dissolved by water, which evaporates away, but this can be reversed with more water, over and over.

The downside is that managing hide glue seems from my viewpoint to be a specialized skill, because you have very little time from taking it out of the pot, to when it begins to harden, so you have to work confidently and efficiently, and then clean up the excess before it hardens.

A few years ago, I made four identical bedside tables for my family, and I decided to glue them with hot hide glue, in order to get some pretend luthireie practice without destroying anybody's instrument. It was pretty humbling.
 
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#5
as others have said, hide glue is the only way to go here. not the pre-bottled stuff, hot glue.

I avoided the stuff for years but honestly it's just like any other glue. it's nothing to be scared of. yes you have to work fast but no it's not so fast that you cant glue a seam.
 
#6
I know it’s unlikely the back on your bass solid wood (vs. laminated), but if it is, most luthiers would use a “weak” mix of hide glue. They definitely do for a seam repair on a solid top. The reason for a “weak” mix is so the seam gives before the top (or back) cracks due to pressure from temp changes.
 
#8
Tim Skaggs said:
I know it’s unlikely the back on your bass solid wood (vs. laminated), but if it is, most luthiers would use a “weak” mix of hide glue. They definitely do for a seam repair on a solid top. The reason for a “weak” mix is so the seam gives before the top (or back) cracks due to pressure from temp changes.
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I think even with a plywood part you'd want to do that. I wouldn't bet on the strength of the inter-ply bonds. I'd sure rather have a seam open back up again at the seam, than have overly-strong glue result in splitting the plies of a plywood part.
 
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#9
Warm the wood up a bit (like using a hairdryer) so the hot hide glue gives you a bit more time.
It the open part is long you might go incremental to have enough time to clamp before the HHG settles.
No cold bottled glue, but you can use gelatin which is basically cleaned up hide glue and solve it in hot water like hide glue. Might not be as strong as HHG, but that is no problem for a seam and reversible.
 

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