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We've had some unusually cold weather in the Pacific NW, consequently the humidity in the house has dropped to around 28% from the normal 45-55%. This has caused some of my bridges to start lifting off. I used Titebond II. Should I have used a different glue for bridges? BTW, these instruments have gone through at least one winter before with no problems.

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A higher purpose for wood.
Rich Smith
Issaquah, WA

You should have used Titebond Original. Titebond II is known to have problems. It has no place in guitar making, except for limited use in gluing purflings that will be heat bent.

I really doubt that your bridges are lifting because of 28% RH.

The problem is either something wrong with the glue you used
or the the bridge to top joint was poor.

I don't disagree with the previous poster about TB II; I don't
have personal experience ever using that on guitars so have no opinion.

I use only titebond original and have never had any problems with failure. Titebondll is prone to creap and that might be your problem.

Correction! I checked my glue bottles - I did use Titebond Original.

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A higher purpose for wood.
Rich Smith
Issaquah, WA

This sounds like either you exceeded the glue open time when gluing the bridges, or the mating of the surfaces was not as good as it should have been.
Glues that cold creep do not come unglued more easily, they creep if exposed to moderately high temps for too long.

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Laurent Brondel
West Paris, Maine - USA
http://www.laurentbrondel.com/

Could have been an inactive surface, as well. Were all the joints scraped or sanded just prior to glue-up?

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Bob Garrish
Former Canonized Purveyor of Fine CNC Luthier Services

I use Titebond Original for EVERYTHING made of wood on the guitar and have never had an issue like that. I think you may need to check the integrity of the joint as you glue your next few guitars. The dome on the soundboard makes gluing the bridge a bit more of a challenge, and the lifting could be due to a sliver of a gap in there, or possibly a really oily piece of rosewood that just didn't fully bond to the glue. I've never done any leaching with acetone on rosewood bridges before gluing tham, but I hear it helps control the bond better on oily wood. I live in AZ though, so the oil content gets sucked out pretty fast in the desert climate.

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http://www.sixgunguitars.com

A guitar shouldn't be exposed to 28% humidity in the first place!

I use hide glue, because eventually for whatever reason, the bridge may need to come off, so hide glue is the best for repairs. Also I have read that titebond II tends to creep but if it's creeping under a cold environment, I would suspect the very low humidity than the glue itself.

Your guitar should be kept at a 45% humidity environment if possible. If you can't humidify your room, keep it in a humidified case.

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Cat-gut strings are made from kitten guts, stretched out to near breaking point and then hardened with grue saliva. As a result these give a feeling of Pain and anguish whenever played, and often end up playing themselves backwards as part of satanic rituals.

Typhoon Guitars
http://www.typhoon-guitars.com

Tai-fu, your statements are simply incorrect.

My personal guitars are routinely exposed to 25% to 70% RH swings and they're totally fine. I don't like them to stay at 25% for too long, and they usually don't. But they're tools, not jewellery, and a well designed, well constructed guitar should be able to withstand large swings in temp and RH. Do you think musicians control their environment? I think not.
For this very reason, it is important to construct the guitar in a controlled environment, so that it can go either way without too much stress.

The OP issue is not cold creep, but bridges lifting. I am afraid the glue type is not the problem here.
A bridge glued with TB1 will come off as easily as one glued with HHG, and perhaps more easily.
The whole zealotry about HHG is becoming absurd.

Bob's observation is a good one: ebony and rosewoods tend to oxidise on the surface and that will compromise any glue joint. I always sand or scrape both surfaces before gluing, and not only for bridges.

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Laurent Brondel
West Paris, Maine - USA
http://www.laurentbrondel.com/

Laurent has a good point. I would ask this one point , what was your prep method for the bridge. Many times that can cause problems . I also make sure the wood surfaces are fresh . I like to rout the top finish off at the bridge location. Maybe we can help as maybe the problem is in your mounting technique.

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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

Can't agree with that one. 28% RH is abuse to an instrument built in 45%. So is 75-80% IMO.
I use Titebond for furniture, HHG for bridges, and glue a flat bridge to a radius surface, and they don't come off. Agree with sanding or scraping just before glueing.

I do scrape the guitar body where the bridge will be attached. I hadn't thought of attaching a straight bridge to an arched top. I usually sand the bridge to conform to the body top. I may have to install a humidifier on my furnace - who would have thought in Seattle I'd need to do that!!!

_________________
A higher purpose for wood.
Rich Smith
Issaquah, WA