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There has been considerable talk in the Humidor forum as of late regarding the “dehydration process.” In a recent topic about a walk-in humidor project it was mentioned as a recommendation by a tobacconist that a new walk-in be built without sealing it, assuming that the exterior ambient would provide sufficient diffusion of water so that no dehydration process would be necessary. It was at least implied, as I read it, that without leakage and transfer of water to the outside environment, the humidor would over hydrate. That ‘leaving the door open’ or leakage to the outside macroclimate would solve the problem. I find it interesting that dehydration is rarely a topic of humidor study unless I bring it up! In talking to a lot of smokers looking to solve humidor problems, I find it one of the main reasons a cigar enthusiast contacts me. It does appear, at least to me, that this important topic is all but ignored by the mainstream community and humidor builder alike. It would appear also, that many of the folks that I speak with have some sort of issue with high rH. It also appears, that most folks live with it rather than deal with it… While I am not going to bore you with an in-depth discussion of how I solve the problem, I do find it an interesting topic. After studying hundreds of charts of humidor performance, I thought I would parse down yet another chart of one of my humidors to show how I deal with the issue. Of course you need the proper appliances and controls to meet the foe of over-hydration in order to beat it down! I use refrigeration to perform the task, as there is little that strips water from space like a cold plate that is at or below the dew point. Chart A shows an overall view of the process. The chart shows one of my humidors at work in my lab at about 3am. For the record the outside conditions are such that the heater is running in the humidor to keep the temperature up. This has little actual effect on the process itself, but it does act to keep the temperature in the range that I wish to store. Repeated dehydration cycles when the ambient is below the storage set point would eventually decrease the heat and temperature in the humidor over time. This is off topic! Chart B be gives you an idea about how a sealed humidor will act at a low temperature and the duration of the natural cycle of a sealed humidor to over saturate itself with water if left to its own devices. As you can see, it takes 9 to 10 minutes to move from a low-end rH condition to a high-end rH condition in this particular ambient set of conditions. Chart C shows some of the dehydration process and the duration of the dehydration cycle. The dehydration cycle itself runs about a minute and a half. It should be noted that most processes in humidors overshoot their run times. Knowing how to deal with this is learned empirically and learning how to produce desired results is borne out of experience. There is no handbook for it! Only testing and experimentation will yield these kinds of results. Knowing when, how and how long to run appliances is as much art as science. The two square-wave signals are generated by my appliances to track their performance. What you see here is the time line of these appliances actually switching on and off. Without such data I would simply be guessing at where and what to adjust. I thought it would be interesting to show how precision instrumentation performs to keep my humidor ‘in line’ so I included the signals on the chart. This is ‘inside baseball stuff,’ but I thought it might be informative. If I analyze the chart with my software the actual range for the rH throughout the cycle is only about 1.5rH. A cooling cycle itself will take a greater toll as it is easier to remove water than to cool air but that is another story. In my opinion a sealed humidor with an active (wet) humidifier requires a dehydration cycle to remain within [my] limits. If you were at all interesting in how I came to that conclusion… well… this is how! Thanks for reading! -the Pig
I have begun to delve a little into what I call micro analysis of humidor performance. I can't expect it to really excite anyone but me, but there is a certain amount of pleasure derived from making something work, making it work better and trying achieve perfection. It is interesting to see if an idea that you have will really turn into something that you will consider as a standardized design or whether it is a failure. This is the same humidor on two different days with similar temperatures (outside). My goal was to try to shallow the dehydration during cooling above the 80 dF ambient mark and see if I can decrease the frequency or the amplitude of the cycle. Every improvement must do one or both of those things or it is not an improvement! These are high magnification pics of the humidity oscillation due to refrigeration at a high temperature (ambient outside). Any of these very small dips are acceptable to me, but if I could pull them down to as little as 3 rH I would really be pleased. At 80 dF outside, I don't really think it is possible but it does not stop me from trying! Test A is a native process. Cooling cycle begins and hydration follows. The cooling cycle is run until completion and there is residual drying that initiates subsequent hydration cycles. Pretty straight forward. Test B on the other hand was an idea I had about interrupting the cooling cycle when the system called for hydration and then once the system was hydrated again the cooling cycle would resume. This would drag out the cooling cycle, and perhaps over cool, but it would theoretically reduce the large dips in the rH to smaller ones. In cooler weather the system would be unaffected by the design. I am intrigued as to how it works and if I distort the chart to show the dehydration cycles highly compressed with the amplitudes exaggerated it looks like it does work quite well. I will crop some charts and run some analysis on them to look at the average rH, as well as average highs and lows to be sure. Thanks for following. -R