Humidity and Hide Glue Drying Time

[gp_bass]

So I live in Boston, which is always a seasonal adventure for humidity and acoustic instruments. Right now, the RH hovers mostly around 55-60%, but can skyrocket to 70% or so. Avg Temp is about 75-80 degrees.

I've read many times that one should assemble instruments in 40-55% humidity. I assume this is mostly for new instruments, so as to prevent cracking as humidity changes with the younder wood.

What's the philosophy on smaller repairs in humid weather?

If I'm just gluing an open seam or something like that, is it okay to glue in 60% or more humidity? Should I expect a longer drying time (I always wait at least 24 hours before stressing a joint in normal humidity -- how long should I wait in high humidity?)?

I've been restoring an old parlor guitar over the winter and just got around to regluing the bridge. A flattop guitar bridge is of course subject to lots of force from the strings. When's a safe time to try bringing it up to pitch after gluing? I was thinking maybe 3 days or so.

I use Behlen's Hide Glue (from stew mac) throughout.

Thanks.

[Zachary Martin]

Yes, New England weather does pose many problems for our instruments. From my experience humidity matters much less in the glueing of small surfaces. It does play a part in the glueing of larger surfaces, in regard to the glues open or set time.
There is some need to regulate the instruments environment. To expose an instrument to our extreme changes, with no buffer, would be damaging in the long run if not immediate. Try and keep the humidity between 48-55 in summer and 38-45 in the winter
How long should you wait to string it up? 24 hours is more than sufficient. Clamps can be removed after 8-12 hours. Sometimes for larger jobs I will give it a day to acclimate to its new parts. But the glue joint will be as strong as it needs to be in that amount of time.

[uptonbass]

Originally Posted by Zachary Martin

. Try and keep the humidity between 48-55 in summer and 38-45 in the winter.

Zach, don't you mean 45-55 and 35-55. In the coldest days of winter here on the water its a task and a half to keep the shop at 40! I am more of a believer in keeping the humidity at an ideal ALL year long, I think we can settle on 35-55 being great through the seasons.

Originally Posted by Zachary Martin

Clamps can be removed after 8-12 hours. Sometimes for larger jobs I will give it a day to acclimate to its new parts.

24 is always the safest bet, no need to rush.

[uptonbass]

Zach,

Sorry to have jumped on you about that I just thought the eights were a little odd.