Lamination separation

[mmukav]

A friend of mine has an old mandola with a laminated back. The laminations have separated in 2 spots on the back which seem to coincide with the placement of the braces on the back.

Any repair suggestions?

One guy mentioned 'ironing' the back, with the idea of melting the existing glue, then clamping it till it re-dries, or drilling small holes then injecting glue and clamping.

Any other ideas? http://www.mandolincafe.net/iB_html/non-cgi/emoticons/rock.gif

[Luthier]

Any pics? It would be helpful to see the instrument at the place where it is coming apart.


Don

[mmukav]

Sorry, unable to provide pics. But if you look at the instrument from the back, there looks like 2 ripples, or bubbles in the wood on the back. It's not cracked, just lifted up. Everyone that was there when we looked at it was convinced that it was a laminated back, and that the laminations had separated, causing the ripple effect on the back. If you looked in the soundhole, the back looked to be intact, with no cracks, or ripples.

[Rroyd]

Can you push the "bubbles" down to where they are flat, or do they try to wrinkle, like the wood grain has stretched? If they will lie flat, the suggestion that was given to inject glue and clamp should work fine. A syringe with a fine hypodermic
needle and the glue warmed to make it flow easily works well. You could possibly force the needle through the bubble at an angle to where the hole would not even show when the repair is completed. An 18 or 20 gauge needle would be stiff enough to push through the wood if the lamination is a typical veneer. You won't need much glue, just a drop or two. If you get too much, you will end up with what you have now, a bubble, only the new one will have a dried lump of glue underneath it. If the bubbles are fairly large,
a couple of small holes to allow air and excess glue to squeeze out would be appropriate. Clamp just enough to hold them flat. Good luck.

[Luthier]

Do the "ripples" or "bubbles" extend to the end of the wood?
In some cases glue can be injected into them using a small needle and syringe but if they do extend to where there is a visible opening, glue can be worked into them from the opening and then clamped.

Don

[mmukav]

The 'bubbles' are away from the edges of the back and the wood is not cracked. I think the injection method would work great. I'll pass along the info when I see my friend tomorrow. Thanks for all your help. I'll let you know how it goes. Mike