Low humidity building

[tope]

I have humidification in my shop for winter and the best that I can get is about 33% humidity. I also have the AC for summer control. I have a friend that builds harps and insists that he will only glue in the winter when the humidity is very low. Obviously an instrument can come apart when moved to a low humidity environment when glued in too wet a conditionn. What are the pros and cons of glueing in very low humidity?
Thx

[Michael Lewis]

Instruments assembled in very dry conditions will swell somewhat in humid conditions. This can cause stress in the structure, which can cause things to move, neck angle to change, seams to open, etc. It's better to assemble in moderate humidity, about 40% or a bit more, but not good to put these things together in high humidity because when THEY are exposed to dry conditions they open seams and cracks.