[pianotech] Kawai Lyre affected by humidity swings

[Don Mannino]

Barbara,

Yep, it's usually in the driest locations where the lyres come loose the fastest. I would agree with your plan of getting it as dry as possible before gluing it all together again.

Yes, the wood squeezes and crushes a little during high humidity, but it will survive.  Sealing the wood doesn't really work - it might slow down the moisture transfer, but you can't block it altogether.  Just use good woodworking glue, which penetrates into the wood and also remains somewhat flexible.

The grain direction of the wedges might help, but if you have spare pinblock material around it would work very well.

Don Mannino

-----Original Message-----
From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On Behalf Of Barbara Richmond
Sent: Sunday, February 28, 2010 12:03 PM
To: pianotech
Subject: [pianotech] Kawai Lyre affected by humidity swings

Ugh. 

OK, I was busy and didn't get right to the lyre--here's what happened. The RH at the school (where the pianos lives) is low--I'm not sure how low, because my hygrometer went on the fritz, but it must be below 20%, probably more like 15% (or worse). I brought the lyre home to my comfortable house--~30% main level and ~30-40% on the lower level--walk out basement. 
It didn't take long, the posts got tight again... 

I set up a card table with blankets draped over it, and inside I set a heater, the lyre & wedges-- plus my new data logger with LCD display (Al G. I got one, it's nice). It didn't take long for the wood to take on the moisture, how long should it take to dry it out? It's not as loose as it was, yet. If I don't dry it out, I figure it will just loosen up again. Then I was wondering if I manage to dry it out to the level it was, then put it back together with bigger wedges (or whatever), will any damage occur in the spring & summer when the humidity skyrockets? 

Could I reduce the swelling & shrinking by painting CA glue or coating everything with some sort of epoxy on the open surfaces to seal the wood? If I did this, perhaps I wouldn't have to dry out the wood so much? Should I use wedges made out of a particular type of wood for stability? 

Other suggestions? 

Thanks. 

Sigh. 

Barbara Richmond, RPT
near Peoria, Illinois 

PS--- Al G., I decided on the Thermoworks LCD data logger, (TW-USB-2-LCD) http://www.thermoworks.com/products/humidity/index.html because when I was looking to replace the unreliable Mannix hygrometer that hasn't worked well for me and now doesn't work at all, there didn't seem to be many models out there that would measure really low RH. 
So what the heck, now I stop by my computer on the way out the door, plug in the data logger to turn it on and take it with me for the day. It was very helpful setting up the tent for drying out this lyre, since my heater doesn't have the type of thermostat that one can read and I can check the RH in the tent. The button on the data logger starts it up, so one doesn't have to program a time to start it (but you can if you want).