Official Luthiers Forum!

My roomate has gone off to a music festival with a guitar of mine he won in a raffle...made with LMI white glue. He left a thermometer in his trunk and came up with 104f as a max temp during the day. What's the max temp before structural meltdown?
Thanks...

At 104f there 'may' have been some creep with a PVA based glue like LMI White. Inspect closely inside with a mirror and look for any 'shift' in the bracing. You are not looking for a bond failure so much as the tell tale sign of a lateral 'sliding' of the bracing, particularly the UTB, indicated by glue showing on the top where the brace once was before it slipped under string tension and then cooled to re-bond in its new position..only needs to be an ants willy to be of major concern in regards to the structural integrity of the instrument going forward as PVA is a chemical bond and once broken it can never reform with any more strength that snot....

If the temp and duration was enough to allow, the guitar would also show deformity at the bindings/purf where the neck meets the body and also of the rosette...again it only needs to be slight to indicate a shift and therefore a failure of the original bond..and this failure will be apparent ALL THROUGH THE BOX even if the rest still looks OK from the outside...For what its worth I would not work on such a guitar unless it was something very special that justified the effort of removing the top/back to do the job properly...heat damage really can be that devastating.

Cheers

Kim

Thanks Kim,
I think I may have miscommunicated... This was pre-emptive to find out if it was ok to leave his guitar in his trunk whilst he danced shelaligans with the folkies...the answer is no it seems. String tension to be released for safety sake I suppose...
Thanks for the tip...

Being that it gets pretty hot here in Western Australia I may have extreme views. But unless its just a quick A to B trip, backing off the strings is a matter of course for me when travelling with a stringed instrument. The trunk is a much safer option for a guitar than the back seat on a warm day with the hotel room being even better ...Make no mistake, hot cars are guitar killers and THE number 1 reason to NEVER EVER buy a second hand guitar just from images on Ebay...there are heaps of "uneconomical to repair" victims of the sun out there that you just can't pick unless you have the guitar at hand and know what to look for... they can be had cheap no matter whose name is on the headstock for good reason but lots get caught paying much more than they should for what will most likely prove to be a short term bargain.

Cheers

Kim

Good call, Todd. I used to tell clients to treat their guitar like a person - don't leave it where it will get too cold or too hot.

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