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View Full Version : Why all the cracking?



Minker
02-14-2016, 12:56 PM
I recently acquired a 1920s Martin soprano zero. I love it! It's so light and feathery, and so loud! It feels like it's electrified. I'm lucky it has no cracks. (I think) It seems like whenever I read about these old Martin's, there's commonly cracks. If you look on Elderly's site, I think almost every vintage ukulele is cracked. Is this from low humidity? Guitars are bigger. There's so much more surface area, it seems like they would be much more prone to cracking. I never remember hearing about this much cracking with guitars, mandolins, or banjos. Ukes seem like they should be xtra sturdy with the smaller size. Why all the cracking?

jer
02-14-2016, 02:46 PM
Hey Minker. It happens in all kinds of instruments. I don't think ukes are more or less likely to get cracked than any other instrument. Cracks do often come from lack of proper humidity and temperature control. It seems sometimes that can take years to show up in an instrument, and in other cases it can happen quickly. It also depends on if the wood used was properly dried and such before the instrument was built. I think the word some wood workers use is "seasoned". I'm not sure what all goes into the preparation of wood, but I do know about the drying it to a certain point. If the wood wasn't properly prepared, you're more likely to see damage occur. I wouldn't think that would be the case with a company like Martin though. That is probably seen more in the less expensive mass produced ukes where they're trying to push a lot bigger number of instruments out in a small amount of time.
Other than that, accidents do happen...and then some people are just careless with their instruments.

If it's just a crack in the finish, and not the wood itself, that's not as big of a deal. Finish cracks probably happen more often, due to people moving the instrument from one temperature extreme to another quickly. That's one of the main reasons behind not opening up an instrument that has been shipped to you until it has time to slowly adjust to the new temp. Same thing when taking your uke from outside in the cold to back inside. Some say for the latter, 30 minutes is an okay time to wait..but I don't know. I'm sure whether or not it was sealed up in a case matters there.

I hope you enjoy your "new to you" uke. :)

hmgberg
02-14-2016, 02:49 PM
Yes, typically this is a result of low humidity and the wood shrinking. The wood is typically thinner on ukuleles than on guitars and they are braced more lightly as well. I suppose that has something to do with why they are prone to cracking, but unfortunately, there are plenty of neglected, old guitars that crack as well.

Minker
02-14-2016, 05:28 PM
Thank you for your answers guys! I think humidity and thin wood is the reason.
While wood is susceptible to crack if neglected (temperature, humidity or trauma) -- I feel ukes are particularly prone to cracking. I checked my other instruments, and hmgberg is right, uke wood is much thinner. I am disturbed about the humidity though. I really don't want to keep my instruments in the case. I like them hanging on hangers where I can grab them quick. I think I'm going to gamble!!

jer
02-14-2016, 05:36 PM
If they're all in the same room and you can keep it closed off enough, maybe just a room humidifier would work for you. Back in the day, I used to leave a few of my instruments out and just keep a humidifier running in the bedroom where they were. I was able to keep the level in a good spot in that room. I had to check and fill the humidifier every day, but it wasn't too bad... just a thought.
I've heard of some people wiping their instruments down with water or some kinds of oils to keep the moisture level up too. I've never experimented with that, so have no idea how effective it is or how well it'd work.
I think it's true that most people play an instrument more when it is out. I think it's true for me too. Maybe we the people are just lazy. :D haha.

hmgberg
02-15-2016, 02:18 AM
Heating systems dry the air. The humidity outside of your home is of little consequence, therefore. In other words, you can't expect the weather report to provide you with the information you need. You can get a digital hygrometer that will tell you what the relative humidity is in the room where you keep your instruments. They are not expensive. You will want to keep the ukuleles within a range of 45%-55%.

There are other problems associated with low humidity. For instance, the fretboard wood also shrinks when it dries, but the frets don't. If the frets are protruding (and they weren't before) it means the RH is too low. If the top begins to sag, same thing. This can have negative impact on intonation and action and may cause buzzing.

Another issue is that it is best to keep the instruments within the range of acceptable RH throughout the year. When it fluctuates between low in the winter and high in the summer, the wood is expanding and contracting.

If you live in an area where the RH is fairly constant within a good range, you may not have a problem. However, if you have doubts, the hygrometer is a small price to pay for peace of mind. It may be that it would be fine keeping the instruments out of cases most of the year and keeping them in humidified cases during the heating season.

Also, solid wood is far more likely to crack than laminated wood. In fact, I haven't heard of a laminated instrument cracking because of humidity. Just something to bear in mind when you are deciding how to deal with humidity.

bnolsen
02-15-2016, 03:22 AM
The frets part makes sense. Not wanting to hijack the thread too much, but a few weeks back it went from 60s and raining to 20s and snowing in a few hours, then into single digits not long after that.

The used Islander I bought a couple months back (I have forced air, they had baseboard heat) which already had a low action started buzzing badly when playing the G string at the first fret. Raising the saddle action has helped with it but I would really prefer adding relief back to the neck (which would solve the problem, but there's no truss rod).

Similarly the piano teacher has a laminate oscar schmidt that was brought from chicago in the fall. It already had some buzzing problems and a too low nut slot but that same temp drop made the G string lay across the first and second frets. For that one filling and refiling the nut slot worked out okay.

ProfChris
02-15-2016, 04:47 AM
Cracking is pretty simple. Low humidity causes the wood to shrink, and it shrinks more across the grain. The sides don't want to move in and out though, so the stresses are trying to tear the top and back wood apart along the grain line, where it is weakest to these forces. Similarly, when it becomes humid the top and back swell but the sides resist, so top and back will probably dome up, raising the action.

Repeat this cycle regularly, which happens most in the winter with central heating, and eventually the wood gives way.

Builders try to reduce this risk by using wood with a comparatively low humidity when the uke is glued up, doming tops and backs so they can sink before the stresses try to pul the wood apart, and so on. But there is a limit to what can be done.

If like me you live in a UK house with feeble heating and a benign climate outside, then you'll probably be OK if you don't store your uke next to a radiator (heat lowers humidity, and radiators switch on and off throughout the day, the worst possible case!). Of the ukes I've built, the only ones to crack were subject to cycles of high and low humidity.

If you're in the US with snow outside and 80 degrees of temperature inside, then your house is pretty dry unless you take steps to humidify your uke. Martins are no more immune to cracking than other brands because there's no more that Martin (or anyone else) can do to counteract your home environment.

On the bright side, cracks are a nice source of income for professional luthiers, so they'd in theory be happy for you not to humidify (except they all seem sad to see an instrument damaged that way).

If you don't want to humidify, assuming your environment needs it, then get a laminate topped uke or put up with cracks.

drbekken
02-15-2016, 05:17 AM
Very interesting thread, y'all.
Living in the Almost-Arctic, I have never owned a solid wood instrument, much due to the things mentioned here. I stick to laminates, both guitars and ukes.

Ukejenny
02-15-2016, 02:17 PM
Thank you for your answers guys! I think humidity and thin wood is the reason.
While wood is susceptible to crack if neglected (temperature, humidity or trauma) -- I feel ukes are particularly prone to cracking. I checked my other instruments, and hmgberg is right, uke wood is much thinner. I am disturbed about the humidity though. I really don't want to keep my instruments in the case. I like them hanging on hangers where I can grab them quick. I think I'm going to gamble!!

Plenty of old clarinets out there and the wood is much, much thicker than that thin ukulele soundboard. Still, you can see old clarinets with cracks, or even new ones. Even though clarinets get moisture from being played, it isn't the right kind of moisture and can put stresses on the exterior wood surface, causing it to finally give in and crack.