Humidity and the problems it can create

One of the more critical things to watch out for in an instrument is the humidity level surrounding your instrument (or lack thereof). One can put in a Google search and come up with over 600,000 hits on a search on guitar humidity. An explanation can be had at any of these sites. Some can spell it out in plain english and some like to be on the technical side of things with their explanation. Find the explanation that helps you to understand what relative humidity is exactly. The more information you can get, the better. Once you get a grasp on how relative humidity effects your instrument, then you will understand the importance of trying to keep it under control.

Why the alarm?

Through the years, I've talked to quite a few people in the industry. The one thing that keeps being brought up is the fact that companies are not letting the wood air dry as long as they use to. Up until the eighties, most companies would let their wood air dry for 10-15 years. This was great in that the wood was extremely stable with little or no where to go as far as shrinking from drying out when it came to be used. I can remember back in the sixties and seventies, very rarely was the humidity question brought up as to being the cause of a problem on guitars and fretted instruments. Near the end of the eighties, all of a sudden humidity levels were starting to mentioned as being a factor to watch for with some manufacturers. With more companies now bringing to the fore front the mentioning of keeping humidity levels stable, I asked different companies the reason for the alarm for watching humidity levels (Taylor was one of the first to put this in the manual that is received with each guitar). More and more companies through the years jumped on the bandwagon. The best explanation that I received from anyone was that the wood was only being air dried for 5-7 years now because production had been stepped up with more guitars being built each year. Some companies only going 3-5 years. And some companies switching to kiln-dried wood. It is usually the high end instruments from the companies that get the longer air-dried wood to be built with and also from the individual builder that takes the time to keep the humidity under control in his shop. This doesn't mean that your guitar will be free from any problems related to humidity (even on older pieces, humidity can still cause problems). The solid wood instruments will shift and change more readily than those with laminated wood. Laminated woods will still be affected by humidity but to a lesser degree. It still boils down to keeping track of these changes and preventing drastic ups and downs in humidity levels.

The Problems that can happen

We all know that summer will cause the action to rise and the exact opposite happens in winter, but the reasons for these changes can be different. Bodies on acoustics will swell up, necks will shift, and the high frequencies will sound like they are muffled with less sustain overall. When acoustic bodies swell, the action becomes higher which can be a drastic change from how the instrument played in wintertime. This is where a good repairtech comes in handy to be able to analyze what has changed and come up with the remedy to correct the problem. I have seen where the top on an acoustic will remain relatively flat (slight bellying from normal string tension behind the bridge) but the action has gone sky high in summertime. If the neck remained straight and no other seeable reason can be made, more than likely the back has swelled, forcing the neck angle to change. There are times where the top and back will both swell up. When this happens, the instrument should be brought back to a stable humidity level before a determination on a repair can be made. Trying to do any type of action adjustment when the instrument is swelled up is kind of a crap-shoot especially if you don't have a clue as to where the instrument will bottom out in wintertime. This is especially true here in the Northeast along the coast. RH levels can go as high as 86% during summer and drop back to 10-15% in winter. A drastic change for an instrument to go through in a year. I have seen repairmen fail in business only for the reason that they learnt how to do repairs in another part of the country where the RH stays considerably more constant and they don't know how to handle the changes that can occur near the coastal regions. Even just a few miles inland can be a world of difference in RH.

Bridges are another area that can be affected greatly. I have seen where a bridge is properly glued down and last for a few years and in the course of one summer, with the top swelling up so much, that the bridge starts to lift off the top. This doesn't mean that the repairman did a bad bridge reglue when he repaired it, it's that between the top swelling and string tension, the bridge has no choice but to pull off the soundboard. Keeping the swelling in check as much as possible can help to ward off this type of repair being done over. It is not the fault of the repairman. The responsibility falls on the owner and if this happens then the customer should be recharged for the job. A good repair tech can usually determine the cause and where the blame falls.

Necks can also be affected by RH changes. Adjust a neck one day and a few days later, the neck has moved considerably from where she was adjusted to earlier. All because of a change in humidity levels. This is can easily be remedied with further adjustment to fine tune it but cannot be blamed on the repairman. These changes occur naturally in weather and both the customer and the repairman has to keep this in mind. A good repair tech will be constantly checking the RH in his area on a daily basis and can anticipate better where and how the repair should be handled.

Going to the opposite side of the scale and extreme low RH has its own set of problems that can occur. The sound on an instrument can sound thin and brittle in wintertime. The action will drop, sometimes to the point of the strings actually resting on the frets. This on an instrument that back during summertime, the action had to be brought down because of being to high to comfortably play. I have seen where an instrument has dried out so badly in wintertime, that the soundboard looks like a speaker cone with the center of the soundboard actually being lower that the sides. When this occurs, you can almost assuredly guarantee a crack will happen somewhere on the body. Be it the soundboard, back, sides and fingerboard, all from being in to dry a condition that the instrument is kept in. I have seen where a fingerboard can have several cracks in it from drying out to actually getting one long crack down the entire length of it necessitating replacement which is usually a costly expense . This can be avoided to a degree by the customer.

For the instrument that doesn't shift drastically with seasonal changes, the customer may want to have different height saddles made for his instrument so that when he notices a change in action, he/she can put in a different height saddle and bring the action back to a better playing height.

Preventative Maintenance

Now, we enter the grey area. This is where most, if not all the companies recommend some type of preventative maintenance so as to not run into problems later in the guitar's life. These recommendations come as follows

  1. Using a humidifier for the instrument itself, either with a "DampIt" or with a soundhole humidifier
  2. Using a fretboard conditioner for Rosewood and Ebony (any open pore wood).

Now with guitar humidifiers, depending on the instrument, will determine which I use. For instance, a guitar with no electronics mounted inside the body, a "DampIt" works fine. But if there is a pickup system mounted inside the body, then I recommend going with a soundhole type humidifier. This is one that usually covers the soundhole without anything hanging inside the body itself. I have seen where the "DampIt" type of humidifier actually got hooked on a wire and when the customer goes to take it out to be able to play, out comes a wire along with the humidifier. Not a good situation to be in, especially if your getting ready to play on a gig. I have seen where people have used a plastic soap dish used for camping, drilled some holes into it, put in a small sponge inside and keep this inside the case, either in the case itself or the compartment inside the case. This will gradually allow enough humidity into the area to prevent drying out.

There are those that like to leave the instrument out on a stand. There isn't too much you can do during summertime but wintertime is another story. This is where a room humidifier comes in handy. It not only helps the instruments out but makes things feel more comfortable for yourself. The whole trick to a room humidifier is to keep the water level in it as close to full at all times. I've experienced this myself in having the humidifier run out of water in mid-February and two hors later, notice the humidity level in the room drop by as much as 15%. A drastic change for a short period of time. Avoid this from happening as much as possible. Consistant RH levels with slow changes are the best.

As far as oiling fingerboards goes (boy, have I seen this argument discussed heavily), everything depends on the instrument itself. Some people do not believe in oiling fingerboards at all. Others believe it is a necessary evil and some just take it as regular maintenance and except it. Never try using fretboard conditioner on maple or finished fingerboards. It won't do any good. About the only thing to do with maple boards is to keep them clean. If you are playing the instrument on a daily basis, chances are that using a fretboard conditioner is not necessary. Letting a fingerboard dry out can cause a myriad of problems. Fretboards can shrink causing fretends to stick out past the sides of the board. At the same time, the fret slots can open up and cause the fret ends to lift. This causing the frets to be uneven in hgt. and creating individual notes to buzz or choke out. If the drying is bad enough, then the board will crack. I'm not saying that oiling the board will guarantee that these problems won't happen, just that it will definitely slow the process down and help to possibly prevent a repair from being needed. Once again, it all depends on which area of the country you live in and what the instrument requires .

After awhile of ownership, with you being observant on the conditions the instrument is kept in, you'll get to know what needs to be done, if anything, and eventually develop a routine to keep your instrument in top condition.