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I have a set of lower cabinets in my shop that function as a workbench and a dry box. I have cabinet doors in front that have a lot of gaps so there is ventilation. Inside, I have a 60 w bulb hooked to a humidistat that turns off the bulb when the humidity drops to the setting on the dial. It works for me, I only take tops out and brace when the humidity in my garage is right. I've never had a crack .... knock on wood.
The one I have is very similar to this one, except only cost me about $30 back 15 years ago.

http://www.growerssupply.com/farm/supplies/prod1;gs_thermostats_controllers-gs_humidistats_1;pg104300.html

Exact science? No, but nothing I do is.

UV lights are worthless for this. Use incandescent.

That's great, because I actually bought one of those humidity controller gauges from another builder on this forum, so this will be a perfect application for it. I am hoping that it works for me as well as it worked for you. I have dealt with humidity issues in all my work spaces, and I'm hoping this will help.

I think having a humidity controlled cabinet is not a bad technique even in shops that are controlled for humidity, as it is likely easier to keep a cabinet in the desired range than an entire workshop. As I said, Kim Walker uses one and he is a highly regarded luthier, for what it's worth.

Best,

Jonas

The RH is the amount of moisture in the air divided by the maximum amount of moisture that could exist in the air at a specific temperature. For any air mass at a certain temperature the air simply cannot hold any more moisture then it 'rains' that's the dew point. So this bottom number is essentially (the amount of moisture in the air) - (how much water would be in that air at the dew point for that temperature)

RH = Moister in air / How much moisture the air could hold at the given temperature * 100 (to get the percentage)

So since temperature is in the denominator of that equation you can see that if the temperature goes up the denominator goes up thus making the number smaller.

I use a small room dehumidifier in a closet during the summer months. It saves on energy drying a smaller space than the whole room. It has built in humidity regulation.
If you use a light bulb you might be able to plug it into a humidistat to regulate the R.H. This may require rewiring the device to "close" the circuit when the humidity gets too high rather than when it gets too low (as they commonly do). I have rewired one in the past, and IIRC it wasn't too hard to do.YMMV