Double Bass Cold vs Humidity

[jdh3000]

Is keeping a carved or hybrid in a little cooler environment ok if the humidity is tolerable for the instrument?

Case in point; I have my hybrid in a room where most of the time I can control humidity and keep it near 40% RH according to the hygrometers.

If the humidity drops below the point to where my hudifier can't keep up, bringing the heat down a little levels the humidity and the humidifier can work better.

That room has its own separate thermostat from the rest of the house, so keeping it anywhere it needs to be is fine.

So basically, as long as the humidity is being taken care of, can the wood tolerate a little cooler climate? It seems trying to keep the heat up to fight the cold tends to lower the humidity more.

Thank you!

 

[KUNGfuSHERIFF]

That’s not how it works. By lowering the temperature in that room, you’re making it harder for the air to hold moisture, which is why the humidifier kicks on. How is this room heated? If it’s by forced air you’re looking at a delicate dance as long as you live there.

Generally speaking, if you’re comfortable than so is your bass.

 

[jdh3000]

It's central heat, forced I guess...it comes through vents.

I can't move, nor get a better humidifier at the moment. I didn't realize what I was getting into or I would've gotten a plywood.

Thanks...

 

[AGCurry]

I suspect that when @jdh3000 turns the room thermostat down, he's getting less input from central heating (which is dry), so the humidifier doesn't have to work so hard.

The colder air itself won't harm your bass, but quick changes in temperature might. I wouldn't worry. Most carved basses aren't as delicate as you might think.

 

[s0707]

I think you're doing the right thing. Lowering the room temperature is a valid way of increasing relative humidity, which will benefit your basses.

Bit of a long explanation:

Wood absorption or release of moisture is driven by relative humidity. The wood cells try to reach a point of equilibrium with the air next to it. If the air is dry the wood releases moisture; if the air is humid it absorbs moisture. But the absorption or release is driven by relative humidity, not "absolute humidity." You can think of relative humidity as the capacity of air to take in more moisture. If you're at 100% relative humidity the air cannot take any more moisture. If you're at say 10% relative humidity it can readily take in moisture. So the exchange of moisture between wood and air is driven by this capacity of the air to take in moisture. Likewise, you can say the wood also has a capacity of taking or releasing moisture.

The amount of moisture air can take depends on temperature and pressure. Pressure in our day to day life remains mainly constant, so temperature is the one important variable. At higher temps the air can take more water vapor (moisture) and at lower temps less of it. Relative humidity is the percentage of water vapor currently in the air vs. how much the air can hold.

Say for example, you have 1 gram/cubic meter (g/m3) of water vapor at 70 F; and at 70 F and normal atmospheric pressure the air can hold 2.5 g/m3, then you have 1/2.5 = 0.4 fraction, or 40% relative humidity. If you then take that air and lower its temperature to 60 F you still have the 1 g/m3 of moisture in the air, but the air at 60F can hold only 2 g/m3, then your relative humidity goes up: 1/2 = 0.5 fraction, or 50% humidity. Note: don't quote me on the numbers, they are just an example -- I haven't calculated them.

Like mentioned above, as long as the temperature change is not drastic, I think you are doing the right thing.

 

[David Potts]

Which all leads me to think that keeping the bass in a good cover when not in use will help the bass to better accommodate changes in temperature and humidity. Here in Sydney we have the most humid post-Christmas summer made worse this year by La Nina and rain almost every day. Only moderate temperatures in the 80s but we know that one week of hot dry weather reaching the 100s will see danger of fires start to climb again. It is this sort of extreme that has me covering up and moving my instruments. I have heard that places like New York can be even more extreme but you guys traditionally have had much more central heating and cooling than we need, except for a few days at a time.

 

[jdh3000]

I suspect that when @jdh3000 turns the room thermostat down, he's getting less input from central heating (which is dry), so the humidifier doesn't have to work so hard.

The colder air itself won't harm your bass, but quick changes in temperature might. I wouldn't worry. Most carved basses aren't as delicate as you might think.

Thank you! That does put my mind to rest...

 

[KUNGfuSHERIFF]

Storing a bass in a cover renders its’ environment static, which is how you get mold in conditions of extreme humidity.

 

[jdh3000]

I think you're doing the right thing. Lowering the room temperature is a valid way of increasing relative humidity, which will benefit your basses.

Bit of a long explanation:

Wood absorption or release of moisture is driven by relative humidity. The wood cells try to reach a point of equilibrium with the air next to it. If the air is dry the wood releases moisture; if the air is humid it absorbs moisture. But the absorption or release is driven by relative humidity, not "absolute humidity." You can think of relative humidity as the capacity of air to take in more moisture. If you're at 100% relative humidity the air cannot take any more moisture. If you're at say 10% relative humidity it can readily take in moisture. So the exchange of moisture between wood and air is driven by this capacity of the air to take in moisture. Likewise, you can say the wood also has a capacity of taking or releasing moisture.

The amount of moisture air can take depends on temperature and pressure. Pressure in our day to day life remains mainly constant, so temperature is the one important variable. At higher temps the air can take more water vapor (moisture) and at lower temps less of it. Relative humidity is the percentage of water vapor currently in the air vs. how much the air can hold.

Say for example, you have 1 gram/cubic meter (g/m3) of water vapor at 70 F; and at 70 F and normal atmospheric pressure the air can hold 2.5 g/m3, then you have 1/2.5 = 0.4 fraction, or 40% relative humidity. If you then take that air and lower its temperature to 60 F you still have the 1 g/m3 of moisture in the air, but the air at 60F can hold only 2 g/m3, then your relative humidity goes up: 1/2 = 0.5 fraction, or 50% humidity. Note: don't quote me on the numbers, they are just an example -- I haven't calculated them.

Like mentioned above, as long as the temperature change is not drastic, I think you are doing the right thing.

That's a great and very thorough explaination.

Thank you!

 

[stefaniw80401]

I have a similar sitch I'd like to get opined on. I keep my RH at 40-45% with a humidifier in my studio, and a science quality large dial hydrometer. I live in Denver and have forced air heat. Daytime thermostat is programmed for 66°, but nighttime my spouse programmed 55°, which means I have an 11° swing every day. Is that OK? My Martin guitar and carved washburn mandolin are not cracking or warping. The back center seam on my 2003 carved flatback popped open last year between the center and bottom cross braces. Luthier was able to wick in HHG, swell the joint closed and cleat it thru the f-holes.

 

[KUNGfuSHERIFF]

Your smaller instruments are more stable because they’re small, which means proportionally the wood moves less than a bass is likely to, especially a crossbraced flatback.

Every winter day, the temperature in my wood-heated house swings from see-your-breath cold when I get up to about 65 where the basses are kept after I’ve stoked the fire all day.

Again, temperature matters less than shocks to relative humidity. Nobody worries on summer days when the temperature swings 22 degrees and it’s humid as hell.