I have a few vintage shotguns with decent wood that I want to take care of. The humidity varies considerably throughout the year where I live. I am able to (barely) keep the humidity near 50% in the summer when it is very humid with a couple of Eva-Drys and a heating element. The humidity during the winter has been between 20-25%. Is this too dry for the wood? If so, what should I do to keep the wood from drying out too much?
Wood stabilizes to the humidity it lives in, to a degree. This doesn't mean it holds 50% moisture in your safe. Think of it as getting acclimated to it's environment. Normal, dry hardwood we want ~7-12% moisture content to minimize movement. The biggest problems typically occurs when there is a rapid change, like moving from south Georgia to Tucson AZ. A relative humidity change from 85%+ to less than 20%. Fine furniture, and gunstocks, can suffer mightily long term without precautions. A good oil finish slows the gain or loss of moisture in the wood, but does not stop it. The key is to retard the moisture transfer as much as possible; you can't stop it.
Find the method
@rookhawk has described several times in different threads on hand rubbing a bit of oil on a stock to maintain a finish; his method is better than what I had been doing. Then wax the stock
and the metal with Renaissance Wax. This will actually protect the oil finish and slow the moisture transfer even more.
My stocks live in 4-40% humidity depending on the time of year, so there's no need for a dehumidifier in the safe. When we do see 85-100%, it lasts for a few hours, then it quits raining. With a good finish protected by the wax, a week or two in a higher or lower humidity will rarely impact a wood stock. If it does, the stock was not properly oiled and waxed. The most common places for the finish to be inadequate is the barrel channel, under the buttplate/recoil pad, inletting, and at the head of a buttstock on a 2 piece stock; basically, all the wood typically hidden from view. End grain has the fastest rate of transfer, either in loss or absorption.
With your shotguns, maintaining the finish is the key to preventing them from developing cracks over time. Using a humidifier in the winter can mitigate the naturally drier air in the room your safe is in. A little longwinded, but I hope this helps.
