The average relative humidity in Utah is much lower than in most highly-populated areas of the world. Wood brought from damper places shrinks in size as it dries, which sometimes causes guitar boxes to crack (because the differing woods they are made from shrink different amounts and at different rates). Low humidity also eventually causes metal frets to stick out past the edges of previously wider wooden guitar necks. The fret problem can be fixed by carefully filing down both ends of each fret with a small file, but repaired cracks in wood sometimes open up again or new ones form as wood continues to dry.

During the 60's and early 70's I used to keep humidifiers in my guitar cases with the hope of avoiding those problems. However, the humidifiers would often dry-out while I was away on multi-week overseas trips and I eventually decided that the resulting wide humidity fluctuations probably would be more harmful than merely letting guitar wood dry one time to match the local environment.

That seemed to be a good plan for many years, but about 30 years after picking-up my Ramirez flamenco guitar from the Ramirez shop in Madrid and bringing it to Utah its top cracked. Of course, that might have happened even if the guitar had been kept in a humidified case all those years. It also happened so long after the guitar was brought to Utah that the wood probably would have dried about as much as it ever would have prior to development of the crack.

The average relative humidity on the Oregon Coast is of course much higher than in Utah, but even so, the absolute humidity is not nearly as high as in tropical or semi-tropical coastal areas, because the relatively cool air here cannot hold as much moisture as hotter air can. I haven't checked how the average absolute humidity compares between here and Madrid where three of my guitars were made, but despite this location being on the Coast and Madrid being inland the average temperature difference may make the absolute humidities similar.

Whether that is true or not, I have noticed surprising changes in all my guitars since moving here. They have been greater than expected and in directions opposite what I expected.

I have been here about four weeks. Each morning during the first three weeks the tunings of all the strings on all my guitars were flat compared to previous days. Each morning I had to tighten all the strings to bring them back up to pitch. (that also has continued this past week, but the day-to-day tuning changes have become much smaller) Wood expands when it absorbs water. Larger guitars should stretch strings tighter and raise musical pitches, but the opposite occurred. Of course, dry wood is stiffer than wet wood and that obviously had a greater effect than size expansion.

Tap a hard object on a piece of dry wood and a sharp sound with strong high-frequency components will be generated, because dry wood is stiff. Wet wood is more flexible. Tap the same hard object on a piece of wet wood and there will be a dull thud with relatively weak high-frequency components. It therefore seems reasonable to expect that guitars with very dry wood would produce crisp, high-frequency sounds and that guitars with damp wood would produce duller sounds with weaker high-frequency components. As reasonable as that may seem, the reverse happened as my guitars progressively absorbed more moisture each day during the first three weeks. It is difficult to describe the tonal changes (something like trying to describe the flavor of an orange to someone who has never tasted one), but they have been entirely different than I would have predicted. There are clearly more high-frequency components now than before, but that isn't the only change. The overall sound qualities of all my guitars, including my Tsiorba that was made in Portland, Oregon, have dramatically improved.

Those guitars were all made in much more humid environments than exists in Utah. Both their basic designs and individual adjustments made during construction were optimized at the humidities existing at the guitar-making sites. The guitars subsequently dried considerably when they were moved to Utah. Physical dimensions changed and the wood became stiffer (the neck widths of all those guitars decreased enough over time to necessitate filing down the fret ends). The combination of dimension and stiffness changes would have caused stress changes throughout, but the changes most important to sound quality would have been in the sound boxes. Sound box changes due to the extraordinarily dry Utah air obviously changed sound qualities far more than I had realized.

I don't know how to explain how wonderful those guitars now sound. You will just have to come here and hear them for yourself. When you do you also can enjoy a walk in the sand along historic Nye Beach, which is directly west down the hill from our place. Today was a beautiful, short-shirtsleeve day in Newport. I took a light jacket with me when I went down to Nye Beach for a walk this afternoon, but didn't need it, because the temperature was perfect without it. I took this photo with my cell phone on my way down.


-Bob

davinort wrote:Bob, what change in action (string height) did you encounter with this shift in humidity? It would seem that as the wood absorbed moisture, it should raise the action a bit, because the less-dense top will swell more than the ebony fretboard.

The higher humidity here on the Coast caused the strings on all my guitars to move higher above the frets as you expected, but I think for a slightly different reason than you suggested.

The effect of string tension is to pull the saddle closer to the nut. The nut position is supported by the relatively strong compression resistance of the neck. String tension doesn't significantly move the nut because of that mechanical resistance. In contrast, the saddle fits into a wooden bridge that is glued to a relatively flexible guitar top. Because of the relative flexibility of the top compared to the longitudinal incompressibility of the neck, the primary effect of string tension is to twist the bridge around its longitudinal axis and warp the guitar top such that the area beyond the bridge bulges up and the area on the sound-hole side of the bridge depresses slightly (the area beyond the bridge moves up more than the area near the hole moves down partly because the strings attach beyond the center of the longitudinal axis of the bridge and partly because of bracing differences on the two sides). The amount of top warp for a given total string tension depends on top stiffness. Top stiffness depends on wood type, grain structure, top thickness, other top dimensions, bracing, finish, and possibly other things, such as the stiffness of an attached golpeador. However, in addition to those relatively static properties, it also depends on the wood's moisture content. Damp wood is more flexible than dry wood and the higher the moisture content, the more the top will warp with a given total string tension. As the top warps the saddle rotates upward, raising the strings higher above the frets.

That effect was observed in reverse when Peter initially shipped my Tsiorba blanca from Portland to our previous home near Salt Lake City. He had packed it securely inside a guitar case and had then placed the guitar case inside a sealed shipping carton. Inside that protective "cocoon" he had placed some damp material to maintain a relatively-high humidity during shipment into the dry Utah air. When I first unpacked and played the guitar, the action was very low, but even so, there was very little string buzz. However, over the following days and weeks as the guitar dried out the action became too low and the buzzing increased. I mentioned that to Peter. He sent a new bone blank that I filed down to be higher than the original and the problem was solved until we moved here and the action became too high. Out of curiosity I put the original saddle back in the bridge this afternoon and the string height is now once again perfect.

The same thing was observed many years ago when on three different occasions I brought guitars made in Madrid to Salt Lake City. The strings started buzzing on all those guitars after they had been in Utah a while and all their saddles had to be raised considerably.

Another even more interesting aspect of this is the considerable improvement in tonal qualities with the much higher humidity here. Because damp wood is more flexible than dry, damp guitar tops vibrate farther up and down when strings are played. That makes the sound produced louder, but it also changes sound boxes resonances and profoundly changes how guitars sound. I have had all my guitars, but especially my Spanish-made guitars, long enough to be very familiar with how they used to sound. The improvement is amazing.

That also was observed in reverse long ago when I brought my Spanish-made guitars to Utah, although at that time I didn't understand the why. In each case those guitars sounded fabulous in Spain, but much less so after they had been in Utah a while. I remember wondering if the guy who sold me my first Ramirez could have somehow switched guitars before I left the shop, but in thinking back over everything that had happened that afternoon it seemed like that guitar had been constantly within my view from the time I played it.

The change from Spain to Utah was even greater with my Contreras negra. I played that and another almost identical guitar in Contreras' shop quite a while before deciding which of the two to buy. Paco de Lucía also played them both at his place before I decided (that was in the early 70's when Paco was still playing mostly traditional flamenco). Both those guitars sounded wonderful in Madrid, but the one I choose sounded increasingly less wonderful each time I played it back in Utah. Now here in Oregon it sounds like I remember it sounding long ago in Spain.

-Bob

Peter Tsiorba wrote:Bob, when you get tired of mild coastal weather, come and visit me in Portland. We tend to get a lot colder during winter months, February typically being very sunny and cold. It would never substitute for the real Utah winter, but be closer to the temp range nonetheless.

We will be coming to Portland occasionally to visit some of the great restaurants and other things there, although we have been finding more great places to eat here on the Coast than we previously knew about. As for the "mild coastal weather" it is of course usually warmer in winter and cooler in summer here than in Portland, but a couple days this past week we had 50 MPH wind gusts, heavy rain, and temperatures about 10 degrees below normal. However, today was nice enough for a long walk down South Beach, even though the temperature is still below normal.

Anyway, we will be stopping by to see you from time-to-time.

-Bob