My family and I live in Vermont. There are places in the continental U.S. and elsewhere in the world where the variations in climate can have a more pronounced effect on your cello, but not many. It's a good test ground for maintaining instruments: although most places have enough changes in weather to affect cellos in some way.
The effect of humidity on bowed instruments is a subject that, for some reason, has been discussed publicly only recently. Resulting studies indicate that a large percentage of cracks in violin-family instruments are weather related. It certainly seems to be true of instruments that come to our shop for repairs.
Here's what happens. Wood (all wood) swells when it absorbs moisture and shrinks when it loses it. Let's say your cello is very comfortable (at equilibrium) on a Vermont early-fall day: the temperature is in the high 60's, the humidity is 58%. The in February, you spend some serious time with below zero temperatures and humidity less than 10%. (If no humidity is added to your living space your cello is experiencing less than 5%). The wood in your spruce top slowly shrinks laterally – that means that the distance between the grain lines gets smaller – and the top pulls the ribs, or sides, with it. Only, after a short distance the ribs won’t go any further and one of two things happen: either the seams (where the top joins the ribs) open, or if the glue is too strong the top splits (cracks) causing a somewhat expensive repair and a lessened value for your instrument. This same scenario can occur on the ribs or (less frequently) the back.
It is encouraging to note that most tops are attached with an intentionally weak enough glue to, under weather stress, separate before cracks occur. Trouble is, you never know which will happen until something does. But it is also encouraging to realize that there is something that can be done to prevent either. ADD SOME HUMIDITY!
Forget the green plastic snakes you soak in water, wring out, then hang into your cello through the f-holes. As mild as their dampness seems, the water will collect at the bottom of the snake, then drip into the inside of your cello , almost always in the same place since you store your cello in the same position every night. Over time, sometimes several years, this water will rot blocks, dissolve glue, warp ribs, and do several other things that will necessitate costly repairs and make you think about shooting yourself. I still know people who swear by them: but using green snakes is a little like smoking – you’ve been doing it for years and everything seems fine.
I’ve noticed an impressive array of inside-the-case humidifiers on the market recently, some complete with digital hygrometers. And although I haven’t tried them, I have no reason to believe they won’t work: except that every time your instrument comes out of its case for practice or rehearsal, it is plunged into ambient humidity conditions.
Still the best system I know, and it’s not perfect, is to buy a room humidifier ($30-$150 at the hardware store; $1-$15 at a yard sale) and humidify your practice/cello-storage room. Buy a digital hygrometer. They’re not cheap but the pretty brass dial gauges almost always stick, usually at 50% which leads you to feel great about the humidity level while your cello is cracking in several places. Monitor your humidity level daily and don’t let it fall below 30%: not below 35% if possible.
Next time we’ll talk about some of the other effects of weather changes, and how to keep your cello playing great in all conditions.