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Ask the Experts: how effective are instrument case humidity gauges?

Strad readers submit their problems and queries about string playing, teaching or making to our experts

January 26, 2016

Four violin makers, including two from Australiasia, respond to a New Zealand musician’s query regarding the effectiveness (or otherwise) of humidity gauges built into instrument cases.

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The dilemma: Most instrument cases seem to have a humidity gauge in them these days, but I’m not entirely sure how to use mine. What counts as too dry or too humid? And what should I do if my case humidity goes too far in either direction? I have a Dampit that I can use in dry conditions but I have no idea what to do if the atmosphere becomes too humid.
FLORENCE MARTIN, AUCKLAND, NEW ZEALAND

NOEL SWEETMAN Most modern cases are well insulated and do a good job of keeping the contents protected against short-term weather events such as travelling in warm, humid conditions or dry cold. Both of these situations are very common in New Zealand. We can have wild swings in humidity and cold, sometimes all in a single day.

So, what to do when the atmosphere is warm, sticky and humid? If you’re often playing in these conditions and the instrument feels different, then as long as there are no open seams or other structural issues, you should place the instrument in a room with a dehumidifier and wait for the relative humidity to drop to around 50–55 per cent.

The opposite of warm, sticky, humid conditions is dry cold. An example of this would be in air-conditioned rooms in a colder climate, such as winter in the South Island. If you’re playing in these conditions for some time (say 20–40 per cent relative humidity), use a Dampit inside the instrument where possible (follow the manufacturer’s recommendations) and place a bowl of water in the room to improve the humidity.

For stringed instruments in general, wild swings in temperature and humidity can have a huge effect on performance – and sometimes on the structural integrity, especially with older instruments. Musicians should treat their instruments with care, examining them regularly and noting any change to appearance or performance, which could indicate problems related to environment. Ask a luthier for advice if unsure, especially if planning overseas travel from one environment to another (for instance from the northern to the southern hemisphere).

During our own lifetimes we are only short-term caretakers of our instruments, and we should remember that future generations will benefit from the respect and attention we give them while we have them.

DAVID GLANVILLE Many of the instrument cases produced these days have built-in hygrometers, and many of those are there for show as the manufacturers of less expensive cases try to make them look like dearer ones. If you rely on a hygrometer, you should buy a good-quality digital one that gives reliable readings.

First determine what the average relative humidity is for your area. Sydney has an average humidity of about 77 per cent (and can range from 14 per cent to 100 per cent) whereas Canberra’s average is around 40 per cent.

Older instruments seem to be affected more by changes in humidity because the wood is drier. When I was a student my old viola played quite differently in Canberra from how it did in Sydney, whereas my newer violin was much less affected. Monitor your instrument to determine the medium range in which your instrument performs at its best. Once you have determined this, you may need something to absorb moisture from around your instrument as the humidity increases; as it decreases use your Dampit (I remember my grandmother putting a cup of water behind the piano to prevent the soundboard cracking).

Stringed instruments generally don’t cope well with extremes in temperature. When it is hot and humid the glue can soften and seams pop open. The wood can also suck in moisture and ‘relax’, resulting in the fingerboard dropping, and vice versa when it’s dry. Remember, we are talking about climatic conditions that will affect your instrument over several weeks. Other shorter, temporary influences such as air conditioning and central heating will have a smaller effect.

NICOLAS GILLES Instruments of the violin family have been designed to adapt naturally to temperature changes. Because of the way the arching is curved, the wood can expand or contract across the width of the bouts. Most violin cases now come with a standard needle-and-dial humidity gauge, but these are usually not very accurate. If you’re doing a lot of travelling and humidity is a concern for you, it would be better to buy a good-quality digital gauge. For stringed instruments this should read between 40 and 65 per cent. Any lower would indicate an environment that is too dry, and any higher would show an unacceptable level of moisture in the air.

Using a Dampit is a good idea. If the air is too dry you can add moisture by putting a small wet sponge in a plastic box with holes in the lid, and fixing this box inside the case. In dry weather you can also use a humidifier. If the environment is too damp you can use an absorbent bag filled with silica gel (available online) to dry out the air, although it’s easier to add moisture than to take it out.

After playing in a hall with higher humidity than your home, it’s a good idea to leave the case open for a few hours after you get back. When taking an instrument on board a flight, bear in mind that aeroplanes have very dry air, so put the wet sponge in the case beforehand.

A very dry atmosphere increases the risk of plates ungluing, and in the case of a badly fitted violin it can create cracks on each side of the saddle, as well as soundpost cracks. It’s important to minimise the amplitude of hygrometry of the instrument. A safe level of humidity (+/-15 per cent depending your local weather conditions) would be around 50 per cent.

JEFF LOEN Ideal conditions for musical instruments are 50–55 per cent relative humidity at 20 degrees Celsius. I suspect that you are near these conditions on most days in sub-tropical Auckland. Nevertheless, I would recommend monitoring indoor humidity and taking steps to protect your instrument in conditions of dryness (below 40 per cent) and excessive humidity (over 70 per cent).

Dryness involves greater risk than high humidity because your instrument may shrink and potentially pop a seam or crack as unsealed wood on the interior gives off water to the air. High humidity issues including mould growth and corrosion of metal parts are most likely in damp storage areas with poor air circulation. Avoid most high-humidity problems by storing instruments in dry living quarters with good air flow.

I recommend using a factory-calibrated digital hygrometer. These are superior to dial-type analogue hygrometers in instrument cases, which are uncalibrated and show a huge spread in readings.

When your hygrometer indicates dryness, the best response is to run a floor-mounted humidifier such as you might see pouring out mist at a museum. This puts gallons of water into the air, which is often the amount necessary to raise room humidity to a safe level. I do not recommend tube-type instrument humidifiers because in most cases adding a few teaspoons of water to very dry air won’t make much difference. Plus these may leak water inside your instrument.

A cheap but effective approach to protect your instrument from dryness is to place the entire case inside a plastic bag (your violin shop might have spare bags for violin, viola, or cello). A sealed instrument clearly will not lose moisture. This method is particularly useful while travelling.

Noel Sweetman is a luthier based in Cambridge, on the North Island of New Zealand

David Glanville is the director and head luthier at the Sydney String Centre in Sydney, Australia

Nicolas Gilles is a luthier based in Montpellier, France

Jeff Loen is the owner of Kenmore Violins in Kenmore, WA, US

Read: Protecting your instrument in sub-zero temperatures

Read: Protecting your instrument in hot and humid temperatures

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