Hi, everyone. As we head into winter we should be thinking about protecting the investment in our guitars. Especially the acoustic guitars. The two areas we have to watch out for is extremes in temperature and humidity.
Guitars are usually manufactured in controlled environments with temperatures around 70 degrees F and 40 to 55% humidity. An acoustic guitar is made of several types of wood, some plastic, some metal, some glue and organic materials and a thin layer of finish. The inside of the guitar is bare wood. When the guitar is exposed to very cold and then gets very warm, these various elements will expand at different rates. This expansion will probably cause at least some changes in the way your guitar plays, maybe even some slight buzzing. However, at the extremes, it can cause cracks and warping.
For example, it's below freezing, you have your guitar in the back seat of the car. You run in the store for a few minutes but it turns into a lot longer. You finish and go to your destination that has had the furnace on for a long time and the air is dry and warm. Your guitar case is cold to the touch. DO NOT OPEN IT! Wait until it warms up, about an hour or so. Then, if the case was very cold, crack the case a little and let it set longer. This extreme cold to hot can cause what is known as "checking", little hairline cracks in the finish. They don't effect the sound or playability, but they look bad and moisture can work it's way in to the wood. Over time it could ruin the finish.
Low humidity is also another problem for our guitars. Try to keep it at about 40 to 50 % in the area you store your guitar. That can be very difficult, especially in older houses. So, you can get a guitar humidifier that will help. In the bad old days (60's and 70's) I'd put a section of raw potato in the pocket of the case. What a pain and mess! You don't have to do that. There are several humidifiers made for guitar. Planet Wave makes one of the best that I really like. You can get it at most music stores and definitely at Guitar Center (see my buddy Stan).
Here are a few things to remember.
1. Keep your guitar in the case as much as possible.
2. Try to keep your guitar in a coold place (42-50F) for an hour before your go outside.
3. When transporting, warm up the car if possible before putting the guitar in.
4. Try to keep your guitar out of the trunk.
5. Let your guitar warm up in the case if it gets cold.
6. Don't let the guitar get too dry (low humidity).
7. If you use a guitar humidifier, check it often and don't let water spill inside the guitar.
8. Don't store your guitar over or near a heat vent or cold air return.
Bottom line, concern and care for your instrument is an ongoing thing. While the above is aimed at acoustics, electrics should be cared for much in the same way. The manufacturers don't cover cracks due to environments they can't control. And I can't warrant any of the above, also. This information has largely been gleand from my own experiences and observations and from the Internet. If you need more information, you are welcome to ask me and you can contact the manufacturer
Summer time can be just as tough on your guitar as winter. Excess heat and humidity are the problems. You guitar was probably made in what the manufacturer considered average conditions. The closer you stay to that, the happier your guitar will be.
Here are some recommendations from the Laravee website:
Never keep your guitar in a dark cool basement during periods of high humidity. Don’t store it inside its case in such an environment as the moisture accumulates in the tight quarters of the case.
Keep your guitar out of the case. A guitar stand is a good idea as it allows the air to circulate around your guitar. If possible, it’s a good idea to keep your guitar on the second or third level of your house when the weather is warm.
Another factor, which can adversely affect your instrument in the summer time, is high temperature. When the weather is warm, never leave your guitar in the trunk or back of your car. In such locations, the build-up of heat can exceed 66°C or 150°F. Temperatures this high can have a devastating effect on your guitar, as heat can cause the glue joints to loosen. With the loosening of the fingerboard under these conditions, the action will become very high. Please note that this problem will not correct itself when the temperature drops back to normal, and to lower the action in this case would require a major repair job not covered by your warranty.
Spruce tops contain small resin pockets not all that visible to the eye under normal conditions. This is especially true of tight grain spruce and is more common to German Spruce than to domestic spruce. When the surrounding temperature increases dramatically, it causes these resins to expand and try to escape. Of course the only way out is through the finish causing blemishes all over the top. Although this looks disastrous, it is not particularly hard to repair. A competent repair person can correct this problem with a light sanding and polishing of the top. This kind of damage is not covered by your warranty as it is caused exclusively by careless exposure of the instrument to excessive heat.
One more problem worth mentioning here is if the guitar is exposed to bright sunlight for a period of time, a premature yellowing of the top will occur. Imagine getting a tan. This yellowing is not in itself a problem, but if there is some obstruction to the light, say the guitar strap laying across the face of the guitar, it will leave a lighter print in the shape of the obstruction which would be quite a defacement. This is one thing to keep in mind when you put your guitar down during the summer months.