|
[About Us] [Guestbook] [Contact] [Info] |
A R T I C L E S
Temperature and Humidity Hazards of Winter
by Bruce Morrison
This is an update of my January 1988 Newsletter article which Kevin Becker was kind enough to locate in the Archives. As we enter the heating season, it's time for a reminder about the hazards of winter that all wooden stringed instruments face.
Wood is dynamic. It shrinks during the heating season losing humidity in the dry indoor air. Then from April through October it swells as it absorbs humidity. These cycles of expansion and contraction not only make the semi-annual truss rod adjustments necessary, but they subject the wood, the glue joints, and the finish to stresses which can easily produce cracks, and separated seams. Those stresses also loosen braces, frets, and bridges. They can cause necks to back bow and work loose. The Martin pick guard crack is a textbook example of a crack produced by wood shrinking during the heating season.
Wooden stringed instruments are delicate. Very thin pieces of wood which are held together by narrow glue joints are asked to bear a lot of tension. That tension is trying to tear the bridge from the soundboard, the soundboard and back from the sides, bow the neck forward, and collapse the entire structure inward at the neck/body joint. Factor in the seasonal expansion and contraction and you'll begin to appreciate just how fragile these instruments are.
Rapid changes of temperature have a similar detrimental effect on instruments. Not only is a fast heating or cooling likely to cause a wood surface or glue joint to crack, but because the wood and the finish have different coefficients of expansion, the finish will frequently crack, "craze", or "check" as the more rapidly expanding or contracting wood breaks the relatively rigid finish. That is how the checked finish on a guitar occurs.
The two main things you can do to protect your investment are to use a humidifier, and avoid exposing your instrument to rapid temperature changes. During the heating season, indoor air is very dry. A humidifier kept in the case will help prevent an instrument from drying out to the point where it cracks. If you're using a humidifier which goes in the instrument, be very careful to wring out the sponge thoroughly as gravity will cause an overly damp humidifier to leak. Water pooling inside an instrument will damage the wood and eventually the finish. It's a good practice to travel with your instruments in the passenger compartment of your car rather than in the colder trunk. Once you've brought your instrument inside, allow it time to slowly come to room temperature before opening the case. Bringing a guitar from a 20 F car into a 70 F room and immediately opening the case is likely to cause the finish to crack. A case cover with a thermal lining will help.
Back to Top of Page Return to Articles by Bruce Morrison index page]
[About Us] [Guestbook] [Contact] [Info]