The minimum essential maintenance of the instrument is really a question of keeping an eye on the humidity (see “humidity”), wiping off rosin while it is fresh white powder, making sure that the bridge is straight and especially people with fine-tuners, making sure that the pegs are used regularly. Strings, even if they are not broken, need changing regularly for optimum sound.
Bows require most attention, especially beginners and children must remember every time they use the bow to take off the tension, never to force the tension, not to use more rosin than necessary and not to touch the hair. When a hair breaks never pull out the hair, but cut or break it off.
There are some good books that go into more details such as the “Tip Book” series.
If you haven’t used your bow for a while and you open your case and see loose hairs hanging out the bow, you might have an insect (carpet beetle) that eats hair. Look at the break with a magnifying glass or reading glasses and you may see that the break is not clean but nibbled! Look in the case you might find tiny skins shed by the larva, about the size of a small grain of rice but brown and prickly. If you have an infestation the case will have to be thoroughly cleaned and treated with an insect killer (or put in a deepfreeze for 2 weeks).
You can partly prevent this beetle with a lavender in the case. Like all of this family of insects it prefers to “work” undisturbed in the dark, so expose the case to sunlight regularly and check instruments that are not in constant use.
All wood, even very old wood, works. It shrinks when it is dry and expands when damp. Some instruments are more sensitive to humidity changes due to the grain of the wood, their contruction and their size.
In our experience much damage to instruments is due to humidity changes and can be prevented.
If an instrument is too damp it can possibly warp, glue joints can come open, neck angles can become too low (help my bridge has grown too high!) and pegs can become fixed.
If an instrument is too dry, glue joints can also come open and shrinkage cracks can occur and pegs slip.
These things are not covered by insurance.
To prevent damage is it important to know what the humidity is at different times of the year and it is advisable to own a working hydrometer.
In Holland the ideal humidity is 60 procent by a temperatuur of 20 degrees centigrade. Note that warm air contains more moisture than cold air.
The instrument usually takes a day or two to adjust to a change of humidity.
In Holland extremely dry weather usually occurs in winter during a frosty period with east wind. It’s best then to keep the instrument in a closed case or cover and use a special tube instrument humidifier. If you have an extremely dry home it might be advisable to use a room humidifier especially if you have more instruments and/or a piano.
Damp weather in Holland is practically every summer when the heating is off and especially late summer. Try to ventilate the house and the instruments, leaving the case open and storing the instrument in a dry part of the home. Some homes are chronically damp and then it’s advisable to install a de-humidifier in the room where the instruments are stored.