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cellopera

Humidity & all that Jazz

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After reading about humidity on Mr. Burgess’ website a few years ago, I have become very careful in managing my instruments. Bought a room humidifier, a stretto case humidifier (comboed with Dampits) and case/room hygrometers. I started to notice the low humidity levels in rehearsal and concert halls, as low as 21% this past winter. Even though I was very careful, my Cello has opened seams for the second time this year (January/May). Fortunately, the two places that became unglued this time are not as bad, approx. 5 cm in length. Are these sudden differences in humidity levels going to affect a Cello in the long term? When I open the case the hygrometer usually reads between 42-55% and by the time I finish the rehearsal it reads under 30%.

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It takes hours for wood to pick up and release water so if the instrument is in a proper humidity while being stored that is usually enough to prevent serious damage. Not a bad idea to soften the blow a bit by getting to venues early enough to let the instrument sit in the case for a few minutes if you are taking it from a very cold outside temperature to a warm inside one.  I don' t worry much about instruments which get small openings of the top when the weather changes as long as you get them glued up imediately. I do worry about instruments which never open up despite severe stresses as they may  eventually crack. Arching shape and other factors have a lot to do with the stability of an instrument and some experience is needed to get the gluing right so that it holds well but lets go before damaging  stress occurs.

By the way I truly hate dampits and generally reccomend controlling humidity in the storage and practice room rather than in case humidity gadgets.

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I second the hatred of dampits - they are far to easy to misuse. I have seen many damaged labels, water stains, and distorted areas caused by stuffing a dripping wet dampit into an instrument over and over. 

As usual, I agree with Nathan 100%.

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Thanks for the response. Luckily, I usually squeeze and dry the dampits so they don’t drip but I agree that they could be easily misused. Referring to Nathan’s observation, I always had my main instrument in a room near the rehearsal hall, precisely for being able to avoid sudden temperature changes, so that was never a problem. The Cello was most of the time in its case, safest environment. That is why humidifiers changed the game for me, because without them, I would open the case and my hygrometer would read below 30% humidity. Even so, open seams still happened.

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3 hours ago, nathan slobodkin said:

...I don' t worry much about instruments which get small openings of the top when the weather changes as long as you get them glued up imediately. I do worry about instruments which never open up despite severe stresses as they may  eventually crack....

Same here.  I tell my customers that having seams open from seasonal humidity fluctuations is a good thing, because it means that the stresses have been relieved by the seam opening rather than by the wood cracking.  Top seams are generally intentionally glued with weak glue for this reason.  It's much easier to reglue open seams than to repair cracks, and it leaves no permanent damage.  Weak top seams are like a safety valve.

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On 5/10/2020 at 9:28 PM, Brad Dorsey said:

Same here.  I tell my customers that having seams open from seasonal humidity fluctuations is a good thing, because it means that the stresses have been relieved by the seam opening rather than by the wood cracking.  Top seams are generally intentionally glued with weak glue for this reason.  It's much easier to reglue open seams than to repair cracks, and it leaves no permanent damage.  Weak top seams are like a safety valve.

Interesting information, a crack would definitely be way worse. The opened seams are on the back—upper left rib and lower right rib.

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The same principles apply to openings in the back but because the wood is less prone to cracking the glue can be stronger. If all is working right  the back should be glued well enough to encourage adjustments to occur on the top joints.

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Cellopera, you can add me to the list of those who don't care for dampits.

I agree with Nathan, that a 25% change in the humidity during a rehearsal shouldn't make much difference in either the moisture content or the dimensions of a cello. Wood takes some time to absorb and release moisture, so rehearsal-length deviations shouldn't be a problem, nor even airplane flights where the relative humidity level of the cabin air can drop  to near zero. Best to leave the instrument in the case though, rather than taking it out to give an in-flight performance.  :)  If I were taking an extremely long flight (like to Australia), I might put the case containing the instrument inside a large plastic garbage bag to retard moisture loss.

I'd suggest that there is something else going on. I keep my shop between 40 and 60% percent humidity (occasionally going as far as 15 to 90 percent during short hiccups in the humidity control) and haven't had so much as a seam open in about 30 years. Of course, if an instrument came in which had acclimated to either an extremely moist or dry environment, this could easily happen.

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1 hour ago, David Burgess said:

Cellopera, you can add me to the list of those who don't care for dampits.

 

Good to know, I’ll stop using them.

1 hour ago, David Burgess said:

I agree with Nathan, that a 25% change in the humidity during a rehearsal shouldn't make much difference in either the moisture content or the dimensions of a cello. Wood takes some time to absorb and release moisture, so rehearsal-length deviations shouldn't be a problem

I was not aware of that, just presumed that those sudden changes in moisture might affect the instrument more rapidly.

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19 hours ago, nathan slobodkin said:

It takes hours for wood to pick up and release water so if the instrument is in a proper humidity while being stored that is usually enough to prevent serious damage.

I was not aware of that, just presumed that those sudden changes in moisture might affect the instrument more rapidly.

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I'm not quite so down on Dampits as some are, but they do have to be used with care. We spend a fair amount of time showing people how to use them (or any other humidifier) carefully and correctly. The big thing is to make very sure that they don't drip. In dry conditions, don't add more water, add a little water more often, no matter what you are using. We spend a good deal of time every winter and spring dealing with problems caused by low humidity during the heating season. Our back room (where the humidity is kept at about 55% all year) often has a rather large rack of instruments recovering before we can work on them.

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1 hour ago, stringcheese said:

I'm not quite so down on Dampits as some are, but they do have to be used with care.

There is no reason to hang a wet object inside of a violin off the f-hole wing for the purposes of humidification. There are many much better alternatives for humidifying a violin inside its case, in particular, Strettos work really well. And no device is going to keep a violin adequately humidified in a dry environment if it is left out of a humidified case or cabinet for a long period.

People who think that playing their violin in a dry room with a Dampit installed is keeping the instrument humidified are fooling themselves. Any humidity from the Dampit just goes out via the f-holes. 

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37 minutes ago, GeorgeH said:

People who think that playing their violin in a dry room with a Dampit installed is keeping the instrument humidified are fooling themselves.

Yes! It drives me mental to see self delusion on display in this fashion (or at all, really)

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9 hours ago, David Burgess said:

Cellopera, you can add me to the list of those who don't care for dampits.

I agree with Nathan, that a 25% change in the humidity during a rehearsal shouldn't make much difference in either the moisture content or the dimensions of a cello. Wood takes some time to absorb and release moisture, so rehearsal-length deviations shouldn't be a problem, nor even airplane flights where the relative humidity level of the cabin air can drop  to near zero. Best to leave the instrument in the case though, rather than taking it out to give an in-flight performance.  :)  If I were taking an extremely long flight (like to Australia), I might put the case containing the instrument inside a large plastic garbage bag to retard moisture loss.

I'd suggest that there is something else going on. I keep my shop between 40 and 60% percent humidity (occasionally going as far as 15 to 90 percent during short hiccups in the humidity control) and haven't had so much as a seam open in about 30 years. Of course, if an instrument came in which had acclimated to either an extremely moist or dry environment, this could easily happen.

David,

I also seldom see instruments open up while actually in my shop and I think perhaps never on my own instruments between manufacture and sale. However I certainly do see a lot of instruments come in for open seams especially in late winter which I refer to as "cello cracking season". I tell clients that unless they  have an accurate hygrometer and modify humidity according to what it tells them then they will frequently need to have their instruments reglued.

 

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I agree with the above. The Dampit is not the best solution, but a lot of people have them, and if used incorrectly they can do some serious damage. Nonetheless, it is possible to use one correctly, and knowing what you are trying to do and how to do it is the first step. Yes, expecting it (or anything else of that sort) to work while the instrument is kept out of the case for long periods is just wrong. Whatever you use though, the length of time you'd typically have it out to play is not the issue, as long as you put it back in the case with a proper humidifier, used properly, when you are done.

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