Winter, along with the dry conditions of a typical Canadian home, can play havoc with wooden clock cases. In Canada we generally shut the doors and windows to keep the cold air out from mid November to mid March and we may stay inside for days at a time. During our Canadian winter we have difficulty controlling indoor humidity. Most modern homes have a commercial style air-exchanger that is designed to control relative humidity but it can only do so much.
I have dozens of clocks and most do not seem to mind the changes in humidity from season to season other than a rate adjustment. Those vintage clocks that are adversely affected tend to be clocks with thin veneers that separate from the frames of the cases. Less affected are Ogee clocks with thicker veneers.
My Ingersoll-Waterbury time and strike clock from the mid 1940s is a 70 year old clock and not a particularly valuable one to begin with but has been affected with peeling veneer. The peeling veneer is unsightly and must be addressed.
I am not opposed to using modern materials to repair a vintage clock and in this case yellow carpenters glue was used to close the gaps on both the left and right rear of the case. Yellow carpenters glue has a bonding strength of 3 tons and for maximum effect is should be clamped for 24 hours.
Both sides of the case were splitting open. The right was slightly worse than the left. Although I have several clamps I only had one to spare for this little project so, the job was spread over a few days.
Wax paper is placed between the clamp and the veneer to prevent the glue from adhering to the clamp itself.
Once the glue has bonded, the case is lightly sanded in the affected areas, the remaining cracks treated with wood filler and touched up with a dark stain.
Two coats of shellac are then applied.
Not perfect but an improvement.
Clocks and museums
I am not fanatical about humidity as far as my collection is concerned but museums go to great lengths to control humidity. In museums temperature and humidity are interrelated, and must be monitored and controlled in conjunction with one another towards the goal of preservation. Room temperature is usually established according to the needs of visitors, and is set between 18 and 20°C. The relative humidity for the correct conservation of the works displayed usually lie in the limited range between 45 and 50%.
Clocks react to humidity differently. Clocks with wood pendulum rods need seasonal adjusting as the wood contracts and expands with changes in humidity. Wall clocks that have tight doors in the summer are easier to open in the winter as wood contracts.
High humidity can be mitigated through the use of humidifiers if there is sufficient concern about dry air and its effect on clock cases. It is a good option in the winter months.
If you have a modest collection of clocks I would not worry about humidity issues but you can be assured that seasonal changes can have an affect on your clocks.