I'm not sure if this would be called a humidor, but a client wants me to build a case for his acoustic instruments, where he is able to control the humidity. It is going to be a wood display case, made of cherry, with three glass sides and one wood side. He wants to maintain humidity between 40 and 50 percent. What would this do to the wood case itself, specifically the joints? To build a display case is a piece of cake, but Iím not sure how the wood will respond.
From contributor A:
The consideration is that the interior environment will often be different from the exterior environment, but the interior remains stable. If you construct the cabinet from timber equilibrated to the required interior environment, you need to effectively seal the exterior surfaces to retain the stability of the piece. The other alternative is to seal the inner surfaces, but this could allow the cabinet to move more with seasonal changes, leading to a chance of leakage.
In the old days, such things were lead-lined with soldered joints!
There is a level of cabinetmaking that makes solid wood bookcases for rare book collections, etc., with wood framed glass doors that seal out dust and air exchange. These doors are typically inset and have primary and secondary rabbets with the w-strip kerfed in around the perimeter and solid ball catches in two places for retention.
No amount of finishing will seal out moisture exchange, it will only slow it down. Think of the cabinet as being like an exterior door - the thickness, weather-seal, and construction details are what stand up to the differences in humidity.
Since the best environment for people and houses and wood is at 35% RH, I wonder if your client understands the cost of the little gain they will get.