Curing Chamber from the box up My Build

[DonH]

Dropped RH to 88% so it has been bouncing 88.4% and 87.7% temp is at 100.4 F or 38C for the last 4 and a half or 5 hours. I can see a big difference. I think tomorrow morning I can start wilting, it is good because I have tobacco I need to get in there when this bunch comes out.

I'll try that too. I think high humidity is why some leaves cooked.

 

[deluxestogie]

Temperature cooks the leaf. If you go over 104ºF, the leaf will cook green. Just be patient. My yellowing (in a do-nothing chamber) has been taking about 96 hours. The duration of the yellowing will have little effect on the final product. Rushing it, or jacking up the temp may be shooting yourself in the foot. When it's yellow, it's yellow. Then, you're home free.

Bob

 

[DonH]

Temperature cooks the leaf. If you go over 104ºF, the leaf will cook green. Just be patient. My yellowing (in a do-nothing chamber) has been taking about 96 hours. The duration of the yellowing will have little effect on the final product. Rushing it, or jacking up the temp may be shooting yourself in the foot. When it's yellow, it's yellow. Then, you're home free.

Bob

my temps were below 100 the whole time. Next time I'll let it go until the leaves are all yellow and vent it a little more for a little less humidity.

 

[AmaxB]

Another question in my mind when talking temperature. Is it the temperature of the tobacco it's self or the ambient temperature we should want to use as a guide. Every thing I have seen states temperature but does not get very specific or I did see it some place and don't remember seeing it.
The hottest I have gotten was a chamber bottom temperature of 102 F at the start of the curing process to get things warmed up. Top of chamber max has been 98 F Tobacco it's self max has been 97.4 F..
In a paper I read today the finished tobacco was the same in a number of cures while time to cure varied due to different temperatures and RH levels held in the cures.

AnyWho I'm a happy guy at this specific point the leaf is yellowing up, the fear of it might be setting green is for the most part gone. I'm now getting that sweet smell you guys keep asking about and am starting to feel the racks are going to work out. The racks are 26 pounds and I have about 84 pounds of tobacco in there (at green weight). While keeping the RH at 90 -93% it got pretty wet in there and vents did not open that much. After my adjustment they are opening quit often. Tells me the automatic venting is working as it should and the leaf is losing water content.
I look forward to the morning and going on to the next phase. I believe my next batch the yellowing can be done in less than 60 hours but won't know until I do it.
Last note when I peek in the window I am seeing ah 90% yellow.

 

[AmaxB]

Flue Curing Data Log
Yellowing Phase
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[FONT=Arial, sans-serif]Date[/FONT] [FONT=Arial, sans-serif]Time[/FONT]	[FONT=Arial, sans-serif]Heat Box[/FONT] [FONT=Arial, sans-serif]Temp[/FONT]	[FONT=Arial, sans-serif]Top Temp.[/FONT]	[FONT=Arial, sans-serif]Bottom Temp [/FONT]	[FONT=Arial, sans-serif]RH Sensor[/FONT]	[FONT=Arial, sans-serif]Wet/ Dry [/FONT] [FONT=Arial, sans-serif]Bulb RH[/FONT]	[FONT=Arial, sans-serif]Tobacco Temp[/FONT]	[FONT=Arial, sans-serif]Comments[/FONT]
[FONT=Arial, sans-serif]8/10/13 [/FONT] [FONT=Arial, sans-serif]10:30 PM[/FONT]	[FONT=Arial, sans-serif]91.4 F[/FONT]	[FONT=Arial, sans-serif]95 F[/FONT]	[FONT=Arial, sans-serif]102 F[/FONT]	[FONT=Arial, sans-serif]93.00%[/FONT]	[FONT=Arial, sans-serif]89.00%[/FONT]	[FONT=Arial, sans-serif]93 F[/FONT]	[FONT=Arial, sans-serif]Shut Griddle off[/FONT] [FONT=Arial, sans-serif]Started Cure 2:00 PM[/FONT]
[FONT=Arial, sans-serif]8/11/13 [/FONT] [FONT=Arial, sans-serif]6:32 AM[/FONT]	[FONT=Arial, sans-serif]95 F[/FONT]	[FONT=Arial, sans-serif]95 F[/FONT]	[FONT=Arial, sans-serif]97 F[/FONT]	[FONT=Arial, sans-serif]90.00%[/FONT]	[FONT=Arial, sans-serif]W-82 F[/FONT] [FONT=Arial, sans-serif]D-86 F 89%[/FONT]	[FONT=Arial, sans-serif]91 F[/FONT]
[FONT=Arial, sans-serif]8/11/13[/FONT] [FONT=Arial, sans-serif]2:00 PM[/FONT]	[FONT=Arial, sans-serif]96.8 F[/FONT]	[FONT=Arial, sans-serif]96.8 F[/FONT]	[FONT=Arial, sans-serif]101 F[/FONT]	[FONT=Arial, sans-serif]91.00%[/FONT]	[FONT=Arial, sans-serif]Door Not[/FONT] [FONT=Arial, sans-serif]Opened[/FONT]	[FONT=Arial, sans-serif]93.1 F[/FONT]	[FONT=Arial, sans-serif]Running 24 hours[/FONT]
[FONT=Arial, sans-serif]08/11/13 07:50 PM[/FONT]	[FONT=Arial, sans-serif]96.8 F[/FONT]	[FONT=Arial, sans-serif]96.8 F[/FONT]	[FONT=Arial, sans-serif]101 F[/FONT]	[FONT=Arial, sans-serif]91.00%[/FONT]	[FONT=Arial, sans-serif]W-90 F[/FONT] [FONT=Arial, sans-serif]D-92 F [/FONT] [FONT=Arial, sans-serif]92 %[/FONT]	[FONT=Arial, sans-serif]93.4 F[/FONT]	[FONT=Arial, sans-serif]Yellowing has started[/FONT] [FONT=Arial, sans-serif]at 29 hours 50 minutes[/FONT]
[FONT=Arial, sans-serif]8/12/13[/FONT] [FONT=Arial, sans-serif]6:15 AM[/FONT]	[FONT=Arial, sans-serif]98.6 F[/FONT]	[FONT=Arial, sans-serif]96.8 F[/FONT]	[FONT=Arial, sans-serif]100 F[/FONT]	[FONT=Arial, sans-serif]91.00%[/FONT]	[FONT=Arial, sans-serif]W-90 F[/FONT] [FONT=Arial, sans-serif]D-92 F[/FONT] [FONT=Arial, sans-serif]92%[/FONT]	[FONT=Arial, sans-serif]92.7 F[/FONT]	[FONT=Arial, sans-serif]At 40 Hrs. Running well,[/FONT] [FONT=Arial, sans-serif]Am increasing interior general temps to [/FONT] [FONT=Arial, sans-serif]100-103 F [/FONT]
[FONT=Arial, sans-serif]8/12/13[/FONT] [FONT=Arial, sans-serif]9:00 AM[/FONT]	[FONT=Arial, sans-serif]102.2 F[/FONT]	[FONT=Arial, sans-serif]102.2 F[/FONT]	[FONT=Arial, sans-serif]102.5 F[/FONT]	[FONT=Arial, sans-serif]91.00%[/FONT]	[FONT=Arial, sans-serif]W-96 F[/FONT] [FONT=Arial, sans-serif]D-98 F[/FONT] [FONT=Arial, sans-serif]93%[/FONT]	[FONT=Arial, sans-serif]96.9[/FONT]
[FONT=Arial, sans-serif]8/13/13[/FONT] [FONT=Arial, sans-serif]9:45 PM[/FONT]	[FONT=Arial, sans-serif]102.2 F[/FONT]	[FONT=Arial, sans-serif]102.2 F[/FONT]	[FONT=Arial, sans-serif]102.5 F[/FONT]	[FONT=Arial, sans-serif]88.00%[/FONT]	[FONT=Arial, sans-serif]Door Not Opened[/FONT]	[FONT=Arial, sans-serif]96.8[/FONT]	[FONT=Arial, sans-serif]Dropped RH around 2 PM[/FONT] [FONT=Arial, sans-serif]to 88% I just dropped again to 87%[/FONT]

 

[DGBAMA]

Glad to hear the rh change is helping. Enough collective knowledge here to figure out pretty much anything i think.

 

[AmaxB]

Glad to hear the rh change is helping. Enough collective knowledge here to figure out pretty much anything i think.

Amen

 

[AmaxB]

Still got some light green, but it is yellowing through the entire rack,
Maybe tomorrow I can move out of yellowing phase..

 

[leverhead]

Still got some light green, but it is yellowing through the entire rack,

Even with the different varieties? That kind of luck would be worth the wait.

 

[AmaxB]

Ain't over till the Bald Man Sings ~ off key!

Here is some reading in regard to bulk curing
CURING TOBACCO

T. David Reed, Extension Agronomist, Tobacco
​

​

Flue-Cured Tobacco Curing​

Curing flue-cured tobacco should be considered a complex procedure because of differences in type of tobacco (body, stalk position, moisture content, etc.), curing facilities, and weather conditions. It is difficult to use

a set curing schedule because each barn of tobacco is different.


The harvested leaves must be kept alive during the yellowing period so that desirable chemical and color changes can occur. At the same time, sufficient drying must take place so that when yellowing is completed the leaves will be thoroughly wilted. After the leaves reach the desired yellow color, temperature should be raised to kill the tissue and stop further chemical and color changes. If the leaves are killed too early by drying too fast or high temperatures, the color will remain green. After the desired color (lemon-orange) is achieved, the remainder of the cure is merely a matter of drying the leaf and stems to preserve the color.


Tobacco producers may follow different temperature and humidity schedules and still obtain a satisfactory cure. The exact temperature schedule is not critical as long as it is within reasonable limits. Mr. S. N. Hawks, retired Tobacco Extension Specialist at N. C. State University developed a `Simplified Curing Schedule' designed to reduce the complex curing procedure to its simplest terms. The three dry-bulb temperatures (100°F for yellowing, 130°F for leaf drying, and 160°F for stem drying) are well within safe ranges for each curing phase. Wet-bulb temperature for yellowing should be adjusted to fit the needs of the tobacco. The upper limits for leaf drying (105°F) and stem drying (110°F) are conservative.


The following points need to be remembered in following the Simplified Curing Schedule:

1. Remove all surface moisture from the leaves before beginning to yellow them. This may take up to 12 hours, depending on weather and tobacco conditions when the barn is filled. Lower leaves are often more difficult to yellow without developing soft rot.
   
   
2. Yellowing - Start heat at outside temperature and advance temperature 2°F per hour to 100°F. It may be necessary to open vents slightly during yellowing, but care must be taken to avoid setting green color by lowering relative humidity too much or drying too fast.
   
3. Maintain a dry bulb temperature of 100°F until all leaves are yellow. Provide enough ventilation so that when the leaves become yellow, those on the bottom tier will be completely wilted. Generally, a difference of 2 to 3°F between the wet and dry-bulb reading should be maintained.
   
   
4. Leaf drying - When leaves are yellow and sufficiently wilted, the dry-bulb temperature should be advanced 2°F per hour to 130°F. Increase ventilation enough so that the wet bulb does not exceed 105°F. Toward the end of the leaf drying period it will usually be possible to reduce the amount of ventilation without exceeding 105°F on the wet bulb. A 130°F dry-bulb temperature should be maintained until all of the leaves on the lower two tiers are dry.
   
   
5. Stem drying - Dry-bulb temperature advanced 2°F per hour to 160°F and maintained until stems are dry. As long as the wet- bulb does not exceed 110°F, ventilation can be reduced. Toward the end of the cure the ventilators can be essentially closed to conserve fuel while drying stems.

A graphical representation of a bulk tobacco curing schedule provided by Drs. Boyette and Watkins of NCSU is shown on the following page. This differs only slightly from what is described above, except that there is a momentary holding of the dry bulb temperature at 120 F during leaf drying. This would provide for adequate removal of water from the tissue to avoid scalding or sweating of the tobacco.
.

Sorry the photo is so small but to make it bigger would be a blur.

 

[DGBAMA]

Good find.

 

[AmaxB]

The chamber is working, but man it is taking some time to yellow. Getting some browning tips and edges of leaf at front of the racks door end. Within the racks it is yellowing and is looking as though it is doing it evenly and when I go down to check I can smell the sweet smell. You know it is hard to just set temperature and RH than leave it alone. It is like being a 5 year old kid the week before Xmas you just have to investigate the presents.
I moved the Tobacco Temperature sensor / probe to center front rack.
The next batch for Yellowing I will set temperature first 8 hours for a 2 F climb per hour to 38C and hold there. The RH I will set at 75% first 8 hours than change to 87% and hold.

The chamber is working... but I need to develop a feel for running flue cure.

 

[AmaxB]

Today I sort of pulled the plug on the Yellowing Phase, I removed the racked tobacco made slight change to the racks and reloaded. A good thing I did
had a bad spot in there (tobacco). Am now moving on to Wilting a few pic of some of the tobacco still got some green but it should be good by the time the chamber
goes to wilt mode. Also a pic of the PC screen showing a program to ramp and step through the wilt stage. Am Uploading a video explaining this...
.

 

[Knucklehead]

That's a pretty yellow. If Don had a Rookie of the Year award and Innovative Build of the Year, I think you would come away with a clean sweep.

 

[AmaxB]

Video PC communication with the temperature control how it will be working.

 

[AmaxB]

Humidity will be dropping slowly to the area of 50%

 

[Knucklehead]

Knucklehead to Mission Control. Mission Control can you read me? Humidity levels appear to be dropping. Is this by design? Over. Knucklehead out.

 

[Boboro]

Im thinkin on gettin a old army tent wood heater to help in curein. I dont think I could make the computer stuff work.

 

[AmaxB]

Knucklehead to Mission Control. Mission Control can you read me? Humidity levels appear to be dropping. Is this by design? Over. Knucklehead out.

Mission Control to Knucklehead
Tobacco Leaf typically contains 80 to 90% water, when Yellowing about 20 to 30% should be removed. Wilting & Drying of Leaf at 120F humidity should be about 50% and at 135F about 37%.
To avoid scorching it is important to be sure the leaf is dry enough before advancing temperatures above 130F - 135F. (From reading)
.
My little profile created on the PC and sent to the Temperature Control PID as a program to run, I guessed time and ramp values.
My Stalok 17 Yellowed very fast and I lost most of it from over exposure in yellowing.
The Kutsaga 110 required more time than the others (the photos above) and not all but about 50% had some green.
The Common Smoking & VA Bright Yellowed nicely.
Mixing varieties can be a problem......
With my changes to the racks I should have the needed air flow through the leaf to remove most of the green. The profile start is 100F reaching temperature above 104F will take about 2 hrs.
The chamber ran on manual at 100F & 86% humidity for 6 & a 1/2 hours before implementing the profile for the chamber to run on automatic. Am hoping it was enough time to remove most of
the green from the leaf in photos above. Things are looking very good this morning.

 

[DonH]

I am right with you. Only thing I know by observation is that my stick of silver river that are yellowing nicely is substantially lighter in weight than it was two days ago when hung. Hence the idea that a lot of moisture needs to evaporate to get yellowing.

Now that I think of it, I'm not sure that's the case. I think it will yellow with a certain amount of time. The reason I say this is that for types that I air cure that tend to cure green, like Turkish varieties, I stack the fresh leaves and restack them once a day. When I put Bright Leaf into the Cozy Can to flue cure them I had a dozen leaves that wouldn't fit, so I stacked them in preparation for air curing them. They yellowed at the same rate as the ones in the flue curing chamber. And since they were stacked, they wouldn't have lost much moisture. I guess the test would be to weigh the stack at the beginning and at the end and see what the difference is.