I've attached a photo of how I attempt to tackle the winter humidity issue.  I have a glass cabinet that fits my concertinas and on the second shelf, you will see a round hygrometer with which I can monitor the relative humidity.  On the bottom shelf, not clearly shown, are some glass containers.  When the RH gets less than 55% or so, I will fill the vessels with water.  This jacks up the humidity.  This works!  I am also considering this winter to putting material in the cabinet that has a high