# Barrel temp & humidity



## kwb1963

I've read that it's important to maintain temperature and humidity when aging wine in barrels. Optimum seems to be 55 degrees F and between 65-75% humidity. So I bought a small greenhouse and built it in my basement. It's just a plastic tent over metal frame. I put a small humidifier in it, and I can maintain around 70% pretty well. I guess this keeps the wine from evaporating so quickly. and helps maintain the integrity of the barrel seal. I also bought a small air conditioner unit for this summer when the temp rises. Unfortunately, this unit only cools to 62 degrees F. That will have to do. The greenhouse is working great for now during the winter months. It'll be interesting to see how well it maintains temp this summer.


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## Boatboy24

Nice idea. My basement stays between 65 and 68 degrees, thanks to climate control. But it's dry in winter, with the heat going. Hasn't been an issue so far, but I've been wondering if I should worry about the dryness.


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## kwb1963

Boatboy, this is my first experience with barrels. Through Nov/Dec they were losing a lot of wine through evaporation. At least it seemed that way to me. My basement temp has been between 55-60 degrees since I started measuring- mid Dec. But it was somewhere around 40% humidity then too. I stole the humidifier from our nursery (grandkids rarely stay there) and it's more than enough to maintain 70%. Takes constant adjustment though. Dial it back, open it up, refill, repeat...lol.


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## ibglowin

Just remember above ~70% relative humidity you are losing primarily ALCOHOL to the Angels. Below ~70% relative humidity you are losing primarily WATER. You decide what you want to share with the Angels to some extent. 

I prefer to give my Angels mostly water!


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## kwb1963

ibglowin said:


> Just remember above ~60% relative humidity you are losing ALCOHOL to the Angels. Below ~60% relative humidity you are losing WATER. You decide what you want to share with the Angels.
> 
> I prefer to give my Angels water!



ibglowin, I've never read anything like that. I thought you lost both water and alcohol in low humidity. Please explain. Thanks.


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## ibglowin

*Humidity Determines Wine Evaporation*

Even though both water and ethanol evaporate through the barrel, they do so at different rates. Several factors determine the relative evaporation rates, including the differing molecular weights, the concentration-gradient effects of the relative humidity of the cellar, and the concentration of ethanol in the cellar atmosphere.

Surprisingly, little actual research into the kinetics of the relative evaporation rates of the water and ethanol content of the wine has been published. The research that exists seems to indicate that water and ethanol evaporate at roughly the same rate when the cellar humidity is about 70 percent. When the cellar is drier, water evaporates more quickly from barrels than ethanol. This is reversed in a more humid cellar. As a consequence, the ethanol concentration increases in wine in barrels with cellar humidity below 70 percent while the ethanol concentration decreases in cellar humidity above 70.

This doesn't necessarily mean that 70 percent is the optimum level. Barrel rooms with humidity levels above 70 percent will have lower overall evaporative losses even though the ethanol evaporates slightly faster than the water. The rate of ethanol evaporation is affected by the amount of ethanol vapor in the cellar atmosphere as well as the relative humidity of the cellar. More ethanol in the air will slow down the ethanol evaporation rate.

*Concentration Effects*

Non-volatile molecules, and most molecules larger than ethanol, are not removed during barrel aging. Since the élevage removes water and ethanol, this means that the concentrations of these other wine components increase slightly as the wine is aged. The rate and extent of this concentration effect is dependent upon the combined evaporation rate of both the ethanol and water content of the wine.


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## tonyt

So Mike translate that for a marketing major that keeps his barrel in breakfast room at constant 68-72 degrees.


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## ibglowin

My post #4 is about as succinct as it gets. Living in Houston I know the humidity can easily average 90% on many days out doors. Running the AC will drop it inside the house some. The drier it is inside the house the less alcohol you will lose. My cellar averages about 30% RH. Higher in our Summer monsoon season drier in the Spring.


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## kwb1963

ibglowin, thanks for the info. After your initial post, I Googled this topic and found similar info. Guess I'll lower my target average humidity to 55%. 

When I first sealed and then filled my barrels with wine, all the stave joints appeared tight. But after a couple of weeks, I noticed spaces between them. I know the seal is still intact on the inside, but the outside of the barrels was really dry. When I later got a meter and began to measure, humidity was around 40%. Is this a problem?


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## ibglowin

No, 40% is just fine. You will have some seepage over time with these small barrels. Its just a matter of fact. They do not seal as tight as the big ones no matter what.


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## Boatboy24

kwb1963 said:


> When I first sealed and then filled my barrels with wine, all the stave joints appeared tight. But after a couple of weeks, I noticed spaces between them. I know the seal is still intact on the inside, but the outside of the barrels was really dry. When I later got a meter and began to measure, humidity was around 40%. Is this a problem?



I've got the same thing going on. No leaks, but the spaces are noticeable after 5 weeks in these conditions. I just finished racking my first wine out of the barrel and put the second one in. No leaking so far. In fact, when I rinsed it, I used really hot water, and put a solid stopper on it for a couple minutes while I did the final pre racking activities, just to give myself a little peace of mind. I figured a little heat and steam trapped in there for a few minutes would swell the staves back up a tad.


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