Relative OR Absolute levels?? (Full Version)

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kudo -> Relative OR Absolute levels?? (Dec. 2 2011 16:03:26)

OK im so confused when I see all these percentages , i know that 50% is the best humidity level for guitars, but WHAT THE F$@! IS THAT percentage? is that ABSOLUTE or RELATIVE humidity? there's a big difference!!
i bought a humidifier which i fill up with water, but my indicator next to it measures relative humidity, when i leave in the morning i turn it on and the room temp is about 20 C with 22% R.H. and when i get back at night, the room becomes 27 C and 23% RH. so what the hell is going on?? what are we actually looking at ? absolute or relative humidity for guitars? and is my humidifier doing what is supposed to be doing? or should i get another humidifier? or should i try to cool the room by having the windows open while the humidifier is running?

recently i noticed that my blanca has started buzzing in first fret, so im really worried of whats going on as i think im doing my best in humidifying the room and the cases



Rmn -> RE: Relative OR Absolute levels?? (Dec. 2 2011 16:15:46)

quote:

recently i noticed that my blanca has started buzzing in first fret, so im really worried of whats going on as i think im doing my best in humidifying the room and the cases


lol, just don't go as far as dipping your blanca into a bathtub full of water.

I wish I could answer your question, but have no idea



kudo -> RE: Relative OR Absolute levels?? (Dec. 2 2011 16:21:57)

quote:

just don't go as far as dipping your blanca into a bathtub full of water.
[:D][:D][:D] ofcourse [:D]



Ricardo -> RE: Relative OR Absolute levels?? (Dec. 2 2011 20:06:41)

only thing to worry about is SUDDEN CHANGES. NO matter what you keep the guitar at, the change is the danger



machopicasso -> [Deleted] (Dec. 3 2011 8:54:18)

Post has been moved to the Recycle Bin at Dec. 3 2011 9:18:26



Yojimbo -> RE: Relative OR Absolute levels?? (Dec. 3 2011 15:17:55)

I can't comment on what the ideal humidity is for a guitar, but I can say that there is considerably more moisture (humidity) in 27 C air at 23 percent RH than there is in 20 C air at 22 percent RH.

Warm air can hold more water vapour than cool air, so even if the RH is the same, the warm air has more vapour.

Psychrometric tables provide information on the properties of air and water vapour at different conditions. I don't have access to these anymore, but I found a calculator on the web. It says that for your 27 C condition there is 5.2 g water vapour per kg air while for your 20 C condition there is 3.22 g / kg. So your humidifier appears to be working.

Sorry if I'm telling you things you already know.



kudo -> RE: Relative OR Absolute levels?? (Dec. 3 2011 16:30:14)

Ricardo, I guess you mean , you should only worry if its sudden change, where that sudden change is the dangerous change, so in my case I should not worry.

Yojimbo, thanks for taking the time to write this, yes I guess you must be an engineer too? I learned this stuff a year ago in engineering thermodynamics but I completely forgot it, the only the I remember is the concept that warm air holds more vapor. its just that im not sure what perecentage people talk about, if its absolute or relative, you see what i mean and what tempreatures are those percentages based on.



ToddK -> RE: Relative OR Absolute levels?? (Dec. 3 2011 16:39:12)

You dont want to store
your guitar at say, 20 percent, or 90 percent.

I think Ricardo is thinking of Temperature, not Humidity.

I dont believe a sudden humidity change (if that even happens, i dont think
it does unless you're traveling) would hurt anything.

Say for instance, you store your guitar at around 60 percent. Then you take it out of the case in a different area that is really dry, like 20 percent.

Unless you stay in that area for a long time (days), its not going to do anything.

BUT;
If you leave your guitar in a freezing cold car all night long, dont take it into
a heated house and open it right up. Take it in, and let the case adjust
to the heat first. At least a few hours.

This is what i was told by Richard Brune when i bought my guitar from him.



kudo -> RE: Relative OR Absolute levels?? (Dec. 3 2011 16:43:53)

ok, but you are not answering the main question, when you say 20 percent or whatever percent, what is this percentage based on? Relative or Absolute? if so, at what tempreature is that percentage based on? an assumption of 20 C?



Arash -> RE: Relative OR Absolute levels?? (Dec. 3 2011 17:04:35)

I am pretty sure that it is "relative"



marrow3 -> RE: Relative OR Absolute levels?? (Dec. 3 2011 17:05:27)

Relative humidity is a percentage of the maximum water the air can hold at a given temperature before condensation occurs. Absolute humidity has units like g/m3 or similar. I had to do a load of temperature - humidity tests a couple of years ago on some glucose sensors.

www.tis-gdv.de/tis_e/misc/klima.htm



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