Dear friends,
I've been living in Singapore which is up to 30 Celsius, 90% relative humidity and even with a dry room, we've been running into issues with guitars until recently....
When I looked into relative humidity (RH) & absolute humidity (AH). It changed how I set up my dry room. Actually, I had looked into this when I was in London but had simply ignored it until now.
This info would be useful for anyone looking to care for their instruments, as the calculations can be worked either way for overly or under humid environments. I am using as a reference a conversion table issued by a German industrial site.
The main problem we all face is RH, but I believe that we should be looking at AH instead. Absolute humidity, is the actual amount of moisture in the air. IE, the amount of water vapor, usually discussed per unit volume.
Relative humidity on the otherhand is a %, ratio of the partial pressure of water vapor to the saturated vapor pressure of water. It is affected by pressure and temperature.
So even if we consider that the pressure is the same (it may not be), temperature alone is enough to throw things if we look at RH alone.
Say my uke is made in the USA. In a climate controlled environment of say 20 Celsius, 60% RH. This translates to an AH of 10.4 g/m3. (black circle)
It comes to me, at 30 Celsius, 90% RH. This translates to an AH of 27.3 g/m3. (black circle) This is almost 3x the original humidity. Even if I manage to get the RH down, to say 60%, the AH is still nearly double at 18.2 (yellow circle). This was the previous setup, and I was finding the guitars were still being affected.
In fact, to achieve an AH approximating 10.4, I should be looking at an RH of between 30-40% if I am at 30 Celsius. (green circle). The good news is that my dry room temperature is closer to 25 Celcius, so after switching to a target of 50%, I find things normalising.
The situation may be reversed in ukes, if you stay in a dry climate and the ukes were manufactured in a hot humid environment, say, vintage ukes in Hawaii. You would be looking at humidifying to close to 100% at 20 Celsius to even have a hope of matching 30 Celsius, 60% RH. Luckily old school luthiers were quite cunning and tried to perform critical tasks during periods of lower humidity.
Hope that helps and sheds a little light on humidity.
Incidentally, the pressure will also affect humidity, so the closer to sea level, the more humidity the air can hold and vice versa.
I've been living in Singapore which is up to 30 Celsius, 90% relative humidity and even with a dry room, we've been running into issues with guitars until recently....
When I looked into relative humidity (RH) & absolute humidity (AH). It changed how I set up my dry room. Actually, I had looked into this when I was in London but had simply ignored it until now.
This info would be useful for anyone looking to care for their instruments, as the calculations can be worked either way for overly or under humid environments. I am using as a reference a conversion table issued by a German industrial site.
The main problem we all face is RH, but I believe that we should be looking at AH instead. Absolute humidity, is the actual amount of moisture in the air. IE, the amount of water vapor, usually discussed per unit volume.
Relative humidity on the otherhand is a %, ratio of the partial pressure of water vapor to the saturated vapor pressure of water. It is affected by pressure and temperature.
So even if we consider that the pressure is the same (it may not be), temperature alone is enough to throw things if we look at RH alone.
Say my uke is made in the USA. In a climate controlled environment of say 20 Celsius, 60% RH. This translates to an AH of 10.4 g/m3. (black circle)
It comes to me, at 30 Celsius, 90% RH. This translates to an AH of 27.3 g/m3. (black circle) This is almost 3x the original humidity. Even if I manage to get the RH down, to say 60%, the AH is still nearly double at 18.2 (yellow circle). This was the previous setup, and I was finding the guitars were still being affected.
In fact, to achieve an AH approximating 10.4, I should be looking at an RH of between 30-40% if I am at 30 Celsius. (green circle). The good news is that my dry room temperature is closer to 25 Celcius, so after switching to a target of 50%, I find things normalising.
The situation may be reversed in ukes, if you stay in a dry climate and the ukes were manufactured in a hot humid environment, say, vintage ukes in Hawaii. You would be looking at humidifying to close to 100% at 20 Celsius to even have a hope of matching 30 Celsius, 60% RH. Luckily old school luthiers were quite cunning and tried to perform critical tasks during periods of lower humidity.
Hope that helps and sheds a little light on humidity.
Incidentally, the pressure will also affect humidity, so the closer to sea level, the more humidity the air can hold and vice versa.