temperature, %RH and dew point calculator

[skychaser]

Here is a link to a website that easily calculates values for temperature, %RH and dew point. It also give a risk value for mold.

http://www.dpcalc.org/

Welcome to the Dew Point Calculator

"Want to provide the best combination of temperature and relative humidity (RH) for long-term preservation of collection materials? Use this calculator to explore various combinations of temperature, RH, and dew point and compare the preservation quality of each environment.

The dew point temperature determines what combinations of temperature and RH will be possible in the storage environment. At a constant dew point, when the temperature goes up, the RH goes down and when the temperature goes down, the RH goes up. Controlling the dew point is key to managing the risk of material decay."

 

[springheal]

Thanks for the link.

Will be very useful.

 

[deluxestogie]

Clever little calculator. Setting the RH to 65% (on that calculator) allows the temp to be set at nearly any expected indoor temp without risk of mold.

As a calculator for preservation, I assume the mold risk is aimed at paper. Different materials (paper, leather, cheese, wood, ceramic, etc.) have differing mold risks under the same conditions, depending mostly on the substrate nutrients--mold loves bread, cheese and leather nutrients. These differences cannot be selected on the calculator.

I have kept my chest humidor at more or less 60-65% for the past 40+ years. No mold on the wood. No oxidation of the brass screws. No mold on cigars. No mold on any tobacco (that was not sealed in a bag at too high a case). Much of the leaf or shred kept in the humidor is started in low case, and sealed in freezer Zip Locks (which are slightly vapor permeable).

Bob

 

[deluxestogie]

I've been playing with that dew point calculator. If you set your planned kiln conditions (temp, humidity), you can get a rough estimate of mold risk.

Macanudo's CT Shade is sweated at 98ºF, which is high-risk for mold. If you adjust the humidity slider, it will provide a ballpark humidity (at 98ºF) that will minimize the mold risk.

If you set the RH slider to 100%, you can then fiddle with the temp slider to see at what temp the temperature alone will inhibit mold growth. Fun.

Again, I'm not sure how directly applicable it is to tobacco leaf. But it should be somewhere in the neighborhood.

I've bookmarked that page for future play time.

Bob

 

[skychaser]

It seems to be designed for museums and libraries. It could be pretty handy for getting an idea if your curing or drying areas are likely to get mold. I am using it calculate the dew point from the current temp and % of humidity. That tells me if it's likely to freeze at night or not. The air temp can never go lower than the dew point without forming fog, and fog insulates and stops them temp from dropping more. Last nights calculation told me it should bottom out at 37-38f. My thermometer says it hit 36.8f around 6:30 this morning. I'm already into bonus time here. Average first frost date is Sept 10th. The forecast is for a short warming trend and it looks like I'm going to get a few more days yet.

I can't figure out what the preservation metric numbers mean and how it relates to natural aging. Or if, and how that number might be useful to us. /shrug