PDA

View Full Version : 75% humidity, gluing or wait?



Henning
08-05-2016, 11:22 PM
Hello, I have a simple ladder braced model 50s ukulele with mahogny top. One of the top braces is lose, about 30% of its length. Can I glue it at the humidity of 75 % condition or should I wait for drier air?

mikeyb2
08-05-2016, 11:50 PM
I had problems with my first build when I glued the back and top braces around what was probably near 60% at the time. I lost most of the back radius and the top dipped slightly. Lesson learnt. Coincidentally, only yesterday I started gluing up my 2nd ukulele build and at around 40%, I had been waiting for the right moment to do this, as earlier in the day it was near 60%.
So to answer your question, I would say wait until it's drier.
I know you've only 30% of the brace area which may be affected and it may not make too much difference, but why take any chances?

Henning
08-05-2016, 11:59 PM
Thanks mikey, one matter is that the top is bulging down (between where the saddle is supposed to sit and the sound hole) , as though the strings have bent the saddle off or it was dried out before. I wait´til lower humididty.

Rrgramps
08-06-2016, 05:51 AM
Hello, I have a simple ladder braced model 50s ukulele with mahogny top. One of the top braces is lose, about 30% of its length. Can I glue it at the humidity of 75 % condition or should I wait for drier air?
If you plan to do much gluing, woodworking, or Luthery, invest in a dehumidifier. My shop is at 40% with it on; 70% with it off. I keep it going all the time. It's placed on the other side of the room from dust-producing tools; which I keep to the minimum. Even though my shop is well mechanized, I'm trying to get off the grid and use hand tools, if possible.

Michael N.
08-06-2016, 09:06 AM
The alternative is to build or use a cabinet with a fairly low wattage heater. Around 30 watts should be enough. That should drop the humidity by at least 10 percentage points dependent on how air tight it is, you may well get a much higher drop than that. You then condition the wood in the cabinet for a few hours, remove and then do the glue up. Another alternative is to buy a cabinet or wardrobe dehumidifier and use that. It's far easier to remove moisture from a small space than it is a much larger one. Even at full tilt my room dehumidifier only drops RH by 7 or 8%.

Pete Howlett
08-07-2016, 12:16 PM
Make a control cabinet to keep you parts stable in. Whip em out, apply glue, allow to fully grab under pressure for about 10 minutes, remove clamps and restore to control cabinet... As a rule of thumb I keep my workshop to the conditions in the average living space in most homes. I also make a note of where in the world the instruments go and make sure our workshop heating is around 72 degrees with the rh between 45% and 55%.