How do I protect instruments from summer heat? - July 2002
After a few 90° -105° days, most people have a personal appreciation that heat might damage an instrument. But instrument damage can happen on mild days also, especially if you don’t understand HOW heat affects wood, glue & finish.
If the outside temperature is over 75° , don’t keep your instrument in a parked car or in the trunk of a car that you’re driving. Your car, the air around it & the pavement on which it rests absorb energy from sunlight & turn it to heat. The inside of the car gets much hotter than the air around it. On an 85° F day, for example, the temperature inside your car (with the windows opened slightly) can reach 102° F in 10 minutes and 120° F in half an hour. Warmer days will drive the temperature in your car even higher. With sufficient heat, instrument glues become soft & rubbery & string tension can literally pull the instrument apart. The neck rotates forward in its block. Glued-on bridges lift or come off completely. Braces loosen or separate completely from the surfaces that they're designed to support. The sides of the instrument begin to straighten, separating from the top & back of the instrument. Damage that costs hundreds of dollars to repair can happen in just a few minutes. Some damage can’t be repaired.
When you’re outdoors on a hot day, keep your instrument in shady areas if possible. Sunlight warms things quickly & thoroughly. So, when possible, play your instrument in shady areas if you’re outdoors on a hot day. And, if your instrument is in its case, take special care to stay out of direct hot sun. Although a case usually protects your instrument, dark-colored cases absorb heat from sunlight especially well. Absorbed heat builds significantly inside the case especially if the case sits in direct sun on a hot day when the air can’t dissipate the heat.
If you go into an air-conditioned building from hot outdoors temperatures, put your instrument in its case for the transition. While the temperature change is not as drastic as that of going from a heated building to a wintery outdoors (& the milder transition is unlikely to cause the finish damage that can occur in drastic temperature changes) going from a 95° to 70° is still a significant temperature drop. The strings, wood & glue of the instrument all contract at different rates as they change temperature. And, as the glue contracts more rapidly than the wood, it can form micro-cracks when it tries to shrink & is constrained by its adhesion to the wood. Over time, & especially if the instrument experiences regular temperature shocks, the cracks can grow & link together. In time, the cracks can compromise the strength of the glue joint so much that the neck can rotate, the bridge can lift, the braces can come loose. Coupled with overheating, repeated thermal shocking can even more significantly affect your instrument.
If your situation requires you to have your instrument where it might get too hot , consider getting an insulating case-cover. Several manufacturers make thermal case covers that protect instruments in two ways: reducing heat build-up by reflecting (instead of absorbing) sunlight & by insulating the case from its surroundings. While the covers are costly (generally more than $100), they do buy you a little leeway with regard to summer heat.
What Can I Do?
A good rule-of-thumb is to expose instruments only to temperatures that are comfortable to you.