I'm thinking of going to take a look at a guitar just for knocking around, and maybe selling to one of my students. It's a typical $700 - $800 Valencia student guitar, all solid wood, etc. that I might be able to buy for $250 - $300, advertised as like new. The present owner bought it new about one to two years ago, and knows nothing about keeping a new guitar humidified. Consequently it has just been sitting in an apartment with heat, etc. Because of the time lapsed, what are the chances of it eventually warping or cracking even if I start humidifying it immediately. Or is the situation such that if that has not happened yet, it shouldn't happen once I get it and keep it properly humidified. I'm just worried that possibly a warping process is under way though not yet manifested, and might develop after I get the guitar.

If it has not fallen apart already, and plays well, than perhaps you can get away with not even attempting to humidify it, why not? Also, most factory guitars are put together with somewhat elastic glues. The glues "give" a little when under stress, and reduce the chance of cracking. Not the best glue for acoustic reasons, but it works to diffuse stresses when the wood is subjected to temperature and humidity fluctuations.

Thanks Peter -

So then basically there's not really such a thing as "incipient" warping, that might not show yet, but might show later? Or put another way - it's warped or it's not. Also, even though I might not have to humidify it, I assume it would do no harm if I do?

What would be a typical time period - if there is such a thing - for a guitar to warp from lack of humidifying?

Thanks -
Ramon

"Warping" has a certain negative connotation, so I prefer to use the word "expansion" or "contraction" Since the nature of wood as a material is hygroscopic, it continuously absorbs or sheds water present in the air, even if the guitar is many, many years old. If you begin the process of humidifying your guitar, you may notice changes, although the chance of cracking anything due to extra humidity is low-to-none. Cracks usually develop due to excessive dryness. I don't believe you have a particular reason to worry about "hidden damage" with a dry guitar. If you cannot find any now, it is not likely to "show-up" later. What is likely to happen is that extra humidity will cause any protruding fret ends to "disappear" and the action to change somewhat.

Thanks again Peter - you understood exactly what I was trying to find out. I will take a look at that guitar, and if it looks okay, now I wouldn't have any qualms about buying it.

Relatively humidity tends fluctuate over very wide ranges in high-elevation inland areas such as Utah. I have a private weather station that constantly measures local relatively humanities, dew-points, temperatures, barometric pressures, wind speeds, wind directions, and rain fall rates. Associated software continuously displays real-time data plots in addition to 30-minute, daily, and monthly bar charts and other information.

It is not uncommon for the relatively humidify to drop below ten-percent here in the summer. It is not uncommon to have fog in the winter where the humidity is 100-percent. It also is not uncommon to have wide relative humidity swings over periods of a few hours. These two recent 24-hour relatively humidity bar charts show what commonly occurs here.



I was very concerned about the humidity swings here when I bought a Ramirez classical guitar in 1966 and a few years later when I bought Contreras and Ramirez flamenco guitars. I kept those guitars in humidified cases for many years after purchase. However, it was a nuisance to keep them humidified and it seemed to me that the shock of extreme sudden humidity changes when I took them out of their cases to play them might be worse than letting them experience more gradual natural changes, so I eventually stopped using humidifiers and for the past several years have generally left them uncased on guitar stands where they are easy to pick-up and play.

The Ramirez flamenco guitar did eventually develop a crack in the top that Peter Tsiorba recently fixed. However, that crack occurred more than twenty years after I stopped keeping the guitar in a humidified case and I don't know that it wouldn't have occurred anyway. Neither of the other guitars have suffered any apparent damage. To the contrary, it seemed to me that the guitars all started sounding better after I stopped keeping them in humidified cases. Peter Tsiorba and I happened to discuss that on the phone a couple days ago and speculated that repeated expansion and contraction as the humidity here rises and falls might have an effect similar what happens when guitars "open-up" and sound better after being played a lot.

I am not an expert on the subject, but I think guitarists tend to be overly fearful of humidity changes.

-Bob

It has always been my understanding that warping and cracking problems are less likely to occur from humidity fluctuations, but rather from the wood drying out too quickly due to lack of sufficient humidity. When the contraction occurs over too short a period of time, that's when the problems can happen. But as Peter points out, repeated contraction and expansion is natural, and shouldn't do any harm, and may even do some good.

With respect to the Ramirez, it's extremely doubtful that the crack had anything to do with humidity. After twenty years, surely the guitar had dried slowly enough. But I agree, humidifying a guitar is a pain in the culo.

Things to consider include how your house is heated. In the winter when the heat pump is running the humidity in my house stays 45% - 55%. In colder weather when the electric furnace kicks in, it drops to as low as 41% and rarely goes above 43%. This is based on an inside temperature of 70 degrees. I never gave this much thought until Peter asked so he could brace my guitar for the environment it would be in most. I requested Santa bring me a certified hygrometer and she did. I also bought a small certified one for the guitar closet. During the spring and fall when we have windows open I am sure the inside humidity will fluctuate more. The summers are dry here but the use of AC keeps up the humidity. January seems to be the driest indoor month and that is when the Dominguez cracked while in the case during a period where I didn't play it for over a week. My 1974 redwood and rosewood has never cracked and it has been in high dry elevation to low damp elevation and stored for 2 years in an unheated shed in the case that was boxed. The only guitar that I have owned that ever formed a crack besides the Dominguez was the Mexican Pimental, a cypress and spruce. It first cracked two years after it was made. I think it was from wood that wasn't seasoned properly. In the Dominguez case, I think it was a flaw in the wood that wasn't noticed.

I agree with Bob that guitarist get too obsessed with humidity. It is understandable when one pays several thousand for a fine instrument to be concerned, but unless one has a humidity controlled room where the guitar always stays, controlling the humidity in every situation is impractical, if not impossible.

I agree with the point that the main cause of cracking is due to drying, however trauma should not be overlooked. I have always believed flamenco guitars are made to be played fairly hard, and wear, scratches, and the possibility of cracks are inevitable. I believe in reasonable care, but not to the point of treating it like a museum piece.