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7. In search of lost moisture

A project log for Automated Cigarette Non-Dispenser

A timed cigarette dispenser based on a hacked egg timer

julio perezjulio perez 09/07/2017 at 13:060 Comments

Reminder: The full box takes 2-3 months to deliver the 200 cigarettes it contains, so we have to make sure they don't dry out.

The first solution that comes to mind is to put a wet sponge in the box, unfortunately it doesn't work because the sponge will diffuse water vapor until the air humidity reaches saturation (100%), but the tobacco grows mold above 75%.

Our tobacco roller friends typically use a piece of apple, potato or carrot to re-moisten dry tobacco. This is practical and effective because there is no contact with water, only with water vapor, but can we keep the tobacco for long in this way? We will see.

I put different foods and other products laying around in a closed 3-liter container and left them until the humidity stabilized.

We note that most arrive at 100% or almost, but the surprise comes from a pure butter Madeleine (tea cake):

It stabilizes the air at 72-73% hygrometry (which by the way is the ideal hygrometry to preserve cigars, for those it may concern)

I repeated the test by starting with moist air in the container and the result is amazing:

g with moist air in the container and the result is amazing:

After only 35 minutes, the two curves are less than 1% far of each other. This little cake is therefore capable of diffusing moisture as well as absorbing the excess.

N.B. It is noted that the temperature rises during the measurements, it is due to the heat released by the fan which stirs the air inside the container. For the rest, I varied the speed of the fan to maintain the temperature at 23 ° C. To measure the hygrometry one needs a stable and homogeneous temperature, otherwise the results quickly become unpredictable.

Back to our Madeleines: What can be the cause of this strange phenomenon? Let's havce a close look at the ingredients:

OK no need to look further.

E420 aka Sorbitol (2) is a white vegetable powder used in the agro-food industry for its sweetening and preserving properties.

E422 aka Glycérol aka Glycerin (3) is a viscous liquid obtained from fats ( vegetable , animal or mineral). It is used in the agro-food industry (for the same reasons as sorbitol) and cosmetics, but also as antifreeze (4) , to generate smoke or to feed dairy cows (5).

These two products are highly hygroscopic because of their alcohol functions, they dissolve in the open air by capturing moisture.

We could also call it “unhumectants” because their job here is to keep the humidity below 75% in an airtight package to thirst out molds and bacteria and extend the shelf life.(6)

Although I don't breastfeed at this time, I chose glycerol because it is easier to find in its pure form than sorbitol, which doesn't seem to have any other civil use than that of laxative.

To reproduce the behavior of the Madeleine, let us try first with several concentrations:

So we have:

% Gly% H2OHygrometry
257595.5 %
505084.1 %
752562.7 %

And without taking too many risks, we can add:

% Gly % H2O
Hygrometry
0100100 %
10000%

The smoothed curve:

We zoom in on the area that interests us and we reverse the function:

We try :


71.4%! Not bad!

OK, since we're here and we're focused, why dont we try to calculate the right ratio?

Let's try on next log.

(1) https://www.bosch-sensortec.com/bst/products/all_products/bme280

(2) https://fr.wikipedia.org/wiki/Sorbitol

(3) https://fr.wikipedia.org/wiki/Glyc%C3%A9rol

(4) http://expertsantigel.com/coolant_overview/lavenir_des_liquides_de_refroidissement

(5) https://hal.archives-ouvertes.fr/hal-00888735/document

(6) https://books.google.ch/books?id=rthi4YXGCOgC&pg=PA26&lpg=PA26&dq=humectant+moisissures+bact%C3%A9ries&source=bl&ots=_obVNQIisr&sig=l-_CnXTlQzKUjgtix-ukn3jWDgw&hl=en&sa=X&ved=0ahUKEwie74frpJTQAhVIQBQKHfIICMQQ6AEIQDAE#v=onepage&q=humectant%20moisissures%20bact%C3%A9ries&f=false

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