Thursday, October 9, 2008

Guitarmaking, Climate Change, and The Space Time Continuum (Part II)

Speaking of climate change, let me introduce you to one of the nemeses of guitarmakers – humidity! Dhun dhun dhun..... strictly speaking it's the fairly regular (and frequently sudden) fluctuation of humidity that is the problem. A hygroscopic material is one which attracts moisture from the atmosphere. Wood is absolutely hygroscopic and trying to build guitars in an environment without a controlled ambient humidity is sort of like taking a ride with a blind cabbie on the autobahn, risky. How does one determine the humidity in a space? A hygrometer of course. In fact, you can easily truck on down to your local hardware store and purchase a digital unit for less than a couple dozen Fairmont bagels. Should you ever put one of these quality instruments next to another you will quickly note that they (generally) measure radically different humidites. How could that possibly be? Aren't the numbers depicted in loving digital quality? Isn't the device in infallible? Did I just lock us out of the apartment and if not where are my keys?

The long and short of it all is that hygrometers (like most measuring devices) need to be calibrated. There are a number of different ways to calibrate a hygrometer (google is definitely your friend) but being industrious fellows we looked to our surroundings. In a previous post we mentioned that we brew our own beer and in brewing there are times where temperature is very important. A simple form of hygrometer known variously as a sling hygrometer, a psychrometer, or a sling psychrometer is just a pair of thermometers. One of the thermometers has a bulb that is kept wet and one of the thermometers has a bulb that is kept dry. As ambient air is passed over the bulbs (swinging the thermometers above your head, holding them in front of a fan, strapping them to the back of a unicycle riding monkey trained to navigate figure eights around the band saw) the difference in temperature is recorded. The difference between the two temperatures is related to the ambient temperature and the humidity can be calculated. Obviously (and could be guessed by reading the name of the device), this has to do with the psychometric ratio and can (logically) be numerically computed. If you want to contact us for the formula so you can calculate it every time you want to know what the humidity is please do, we just have a chart (thanks again google!). Anyway, this was a really convoluted way of saying that ensuring that the humidity is “right” for our instruments is a paramount concern and that great care is taken to properly humidify or dehumidify as the situation necessitates. Right now we have a big wick and fan style humidifier (and it works great) but life does tend to evolve...

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