In general, a violin is only held together with glue and the tension of the wooden parts pressed against each other. Changes in humidity and temperature can destroy this delicate balance, so special care must be taken when moving a violin between indoors and outdoors. Each extreme change in environment wrecks a violin a little bit. Over the years, these little disasters add up to a point where, one day, a violin simply falls apart. Sudden changes can also be destructive to a violin. Avoid leaving the violin in direct sunlight for any extended period of time — glue can loosen and varnish may melt.
Storage is just as important. Do not keep a violin in an attic or a basement or anywhere near a vent that blows hot or cold air. The best room in which to store a violin is one that stays at a constant temperature and humidity with as few drafts as possible. Keep the violin in a case of good quality — an violin stored away, but not in a case, puts the instrument in grave peril of being crushed. When opening a case to remove a violin, if the case is either excessively hot or cold, wait fifteen minutes to allow the temperature of the case to equalise with the room’s ambient temperature.
When traveling with a violin, always leave it in the case at all times and keep the case near you. Do not, when riding in a car, put the violin case in the boot of the car — that containment area can act, depending on the season, as either an oven or a freezer, both disastrous places for a violin. You should hold onto the case while in a car, but you can also strap it in with a seat belt in the seat next to you.
A violin can also get too dry, which will cause the joints and the glue to loosen and crack. So, though it is necessary to avoid changes in humidity, a constant humidifier may be needed to keep the violin’s moisture level in balance. A type of small sponge sold on the market as the Dampit can be soaked daily, wrung out and placed inside the body of the violin to accomplish this purpose.
On the other hand, the strings of a violin do not require much maintenance. As a string gets worn out, it is replaced. The best way to keep strung violin strings in a useful condition as long as possible is to buy the highest quality strings you can afford. The horsehair strand of the bow, however, does require periodic waxing with rosin in order to allow the strand to grab hold of the strings during a stroke. No rosin means no sound. Dark rosin is intended for cooler climates, light rosin for warmer ones. Do not put on too much rosin because the excess will drip onto the body of the violin and stain it.
The final step in caring for your violin is simple: examine it continually for damage. Even if the flaw seems minor, bring the violin to a violin-maker as soon as possible so that the little ding does not expand into a major crack. Do your research ahead of time so that you have the name and location of a violin-maker to whom you will have no problem entrusting your precious musical instrument.