# The dreaded stall, evaporative cooling & wet-bulb temperature.



## diggingdogfarm (Mar 15, 2013)

I'm posting this in case someone wants to give smoking at wet-bulb temperature a try as a way to prevent the stall.

I like to keep things short, to the point and understandable, so, as I understand it, in a nutshell:

The stall is caused by evaporative cooling.
The surface moisture evaporates and cools the meat just like sweat cools you on a hot day.
Meat heats from the outside in.
Wet-bulb temperature is a good indicator of the surface temperature of the meat for much of the cooking process.
In a smoker, meat mostly cooks at wet bulb temperature, unless the surface is covered or until the outside is totally dry.
So, when the surface of the meat hits the stall do to evaporation, in order for the surface temperature of the meat to increase and the interior temperature along with it, either the wet-bulb temperature must be increased, the surface of the meat must be covered with foil and the like or the surface must be completely dry.
Drier, less humid air (lower wet-bulb temperature) will cause more evaporative cooling.
The stall is avoided by smoking at a sufficient wet-bulb temperature.

Making your own wet-bulb thermometer:
www.meathaccp.wisc.edu/assets/Wet_Bulb.pdf

References:
http://modernistcuisine.com/2012/08/barbecue-stall/
http://www.genuineideas.com/ArticlesIndex/stallbbq.html
http://forums.egullet.org/topic/134998-the-temperature-stall/
http://www.alkar.com/technical_reports/cooking_truth.html
http://www.huffingtonpost.com/craig-goldwyn/physicist-cracks-bbq-mystery_b_987719.html


Have fun! :biggrin:

~Martin


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## cliffcarter (Mar 15, 2013)

DiggingDogFarm said:


> *Meat heats from the inside out...*
> 
> 
> ~Martin


Not hardly, Pilgrim.


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## diggingdogfarm (Mar 15, 2013)

cliffcarter said:


> Not hardly, Pilgrim.



That was obviously a typo, Pilgrim!!!!
I'm a bit dyslexic at times. :biggrin:
Everybody knows that it heats from the outside in, or they should!!!!


~Martin


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## mdboatbum (Mar 15, 2013)

Unless you're using one of those fancy microwave smokers.


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## diggingdogfarm (Mar 15, 2013)

Well, in my case, that's never going to happen. :biggrin:


~Martin


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## pgsmoker64 (Mar 15, 2013)

Hey...except for the typo....great info Martin.

Easily understandable and plenty of support material.  

A- but only because of the typo...
	

	
	
		
		



		
			






Nice work,

Professor Greene...


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## diggingdogfarm (Mar 15, 2013)

I make a heck of a LOT of mistakes, but I usually get them corrected before others see them......that one slipped by. LOL

~Martin


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## pgsmoker64 (Mar 15, 2013)

Right there with you brother!


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## baconologist (Mar 15, 2013)

Excellent!

I read about evaporative cooling causing the stall and smoking at wet-bulb temperature in Modernist Cuisine.

Great information.


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## snorkelinggirl (Mar 15, 2013)

Mdboatbum said:


> Unless you're using one of those fancy microwave smokers.


I had one of those for a while. Turned out it was from using aluminum foil in the smoker  microwave.


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## aeroforce100 (Mar 15, 2013)

Drier, less humid air (lower wet-bulb temperature) will cause more evaporative cooling

Does that mean if I smoke a brisket or butt in Alabama in August, I will NOT have a stall?


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## diggingdogfarm (Mar 15, 2013)

That depends on the wet bulb temperature. :biggrin:


~Martin


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## mdboatbum (Mar 15, 2013)

DiggingDogFarm said:


> I make a heck of a LOT of mistakes, but I usually get them corrected before others see them......that one slipped by. LOL
> 
> ~Martin


We all do. This is a bbq forum, the exchange of info is the important thing. Hell, I didn't even catch the typo until it was pointed out.  Thanks for the info, though most of it sailed right over my fat head.


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## themule69 (Mar 15, 2013)

great info


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## diggingdogfarm (Mar 16, 2013)

FWIW, here's a FSIS publication which highlights the importance of wet-bulb temperature (rather than dry-bulb temperature) in ensuring proper pathogen lethality.

*"Because evaporative cooling occurs on the surface of thin jerky strips, the wet-bulb temperature is more accurate measurement of product surface temperature."*

http://www.meathaccp.wisc.edu/doc_support/asset/Compliance_Guideline_Jerky_2012.pdf

Lots of other references can be found via a Google search.

~Martin


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## mountainhawg (Mar 16, 2013)

Good info Martin. Never considered this affecting grill/smoker cooking. Since we usually coat with rubs (which get a crust) or in high heat cooking the surface dries, wouldn't this be a short term affect? I can see a short term affect when misting but even there the surface dries again in a few to several minutes.


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## diggingdogfarm (Mar 16, 2013)

I don't pretend to be a scientist, so I must rely on what's offered by others.
Take a look at some of the references I posted and draw your own conclusions.


~Martin


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## mountainhawg (Mar 16, 2013)

DiggingDogFarm said:


> FWIW, here's a FSIS publication which highlights the importance of wet-bulb temperature (rather than dry-bulb temperature) in ensuring proper pathogen lethality.
> 
> *"Because evaporative cooling occurs on the surface of thin jerky strips, the wet-bulb temperature is more accurate measurement of product surface temperature."*
> 
> ...


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## diggingdogfarm (Mar 16, 2013)

Well, it's a government publication we're talking about, so......



~Martin :biggrin:


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## mountainhawg (Mar 16, 2013)

DiggingDogFarm said:


> Well, it's a government publication we're talking about, so......
> 
> 
> 
> ~Martin


I understand what your saying Martin and not disagreeing with you. Seems that cooking  in a smoker or grill has so many variables such as venting, pans of water if they are used, the heat source and moisture content of the smoke material, that moisture content just in the grill alone could vary significantly from smoke to smoke.


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## jarjarchef (Mar 16, 2013)

I may have to play with this when I get either 2 Mavericks or 2 iGrills. Seems to be an interesting adventure to have with the kids........

But my head hurts after reading this.....too much.......


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## diggingdogfarm (Mar 16, 2013)

MountainHawg said:


> DiggingDogFarm said:
> 
> 
> > Well, it's a government publication we're talking about, so......
> ...



Very true.


~Martin


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## mountainhawg (Mar 16, 2013)

jarjarchef said:


> I may have to play with this when I get either 2 Mavericks or 2 iGrills. Seems to be an interesting adventure to have with the kids........
> 
> But my head hurts after reading this.....too much.......


I thought of that too. BUT, when I first got into weather we had to use distilled water to obtain wet bulb temperatures and then later just clean water. When we are talking of lets say jerky, we are talking about evaporation of a mixture of soy, teriyaki, meat fats etc. So we are talking about the evaporation of a mixture of fluids that surely would have a higher evaporation temperature (wet bulb) than pure water, probably much higher.

So I wouldn't recommend someone wrap a piece of wet muslin around one of their probes, lay it next to the jerky and feel that is what the temperature of their jerky is, it's probably higher. The mixture will release water vapor at X degrees which would be higher than a puddle of plain water sitting next to it in the grill.   

My head hurts too!


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## jarjarchef (Mar 16, 2013)

MountainHawg said:


> I thought of that too. BUT, when I first got into weather we had to use distilled water to obtain wet bulb temperatures and then later just clean water. When we are talking of lets say jerky, we are talking about evaporation of a mixture of soy, teriyaki, meat fats etc. So we are talking about the evaporation of a mixture of fluids that surely would have a higher evaporation temperature (wet bulb) than pure water, probably much higher.
> 
> So I wouldn't recommend someone wrap a piece of wet muslin around one of their probes, lay it next to the jerky and feel that is what the temperature of their jerky is, it's probably higher. The mixture will release water vapor at X degrees which would be higher than a puddle of plain water sitting next to it in the grill.
> 
> My head hurts too!


Oh I am not expecting it to be a perfect scenario. I think it would be a cool thing to do with the kids to maybe learn something new....

As mentioned earlier, there are way too many unknown variables in our at home smokers to even begin to have an exact science behind it....


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## diggingdogfarm (Mar 16, 2013)

I've heard that it takes about 58 grams of salt to raise the boiling point of water just 1/2 a degree C???
That's a good amount of salt and not much of a change.
However, I have no idea how that applies exactly, or how any other ingredients apply, to the above 

~Martin


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## kingfishcam (Mar 16, 2013)

Thanks a lot DiggigDog, now I have more reading and a project to build....  :)


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## mountainhawg (Mar 16, 2013)

DiggingDogFarm said:


> I've heard that it takes about 58 grams of salt to raise the boiling point of water just 1/2 a degree C???
> That's a good amount of salt and not much of a change.
> However, I have no idea how that applies exactly, or how any other ingredients apply, to the above
> 
> ~Martin


I think it becomes more an issue of density of what the moisture is trapped in. If one took two shoe laces and saturated one in water and the other in a heavy soy, which contains water, and laid them in the sun, obviously the one with saturated with plain water would dry quicker. BUT if you heated that shoe lace with the soy lets say 25F it may dry at about the same time as the shoe lace with just water. (I just guesstimated in some numbers, nothing firm there). The heating allows for an increase in molecular movement thus an easier release of water vapor (evaporation). So roughly speaking you can say with a grin, the wet bulb temperature of soy is higher than plain water at the same ambient air temperature.-probably all plain as mud
	

	
	
		
		



		
			






  

As for the salt, you are changing the density of the water with the dissolved salt thus raising the boiling point. All depends on parts per whatever and depends on what is being dissolved in the water. 

I think it would take a lot of a dissolved substance to increase the boiling point of water substantially.


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## diggingdogfarm (Mar 16, 2013)

I'm anxious to try a few experiments. 
Wish I was rich! LOL

~Martin


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## mountainhawg (Mar 16, 2013)

I have a 6 pound shoulder all rubbed down in the reefer for tomorrow's experiment. Experimenting with a new rub: 

http://amazingribs.com/recipes/rubs_pastes_marinades_and_brines/meatheads_memphis_dust.html


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## diggingdogfarm (Mar 16, 2013)

Sounds good.


~Martin


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