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ArduinoPID Colour Curing Humidor

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NewZealand

David Walker
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Just thought I'd share my minor successes and major frustrations with colour curing.

I decided to build an oven to control the temp and humidity during the colour curing phase. Its not very good because it's made of fibreboard which is held together with urea formaldehyde resin. That resin releases formaldehyde gas if it gets wet but I painted it so hopefully it will be okay. The oven has very good airflow with 2 fans blowing air all around. The temp and humidity are monitored by a DHT22 which is supposed to be fairly accurate. The ardunio (with PID library) controls the hot plate and ultrasonic mister using solid state relays. This arrangement pleasingly keeps the temp and humidity within 1 degree, and 3% of the set point targets. I've programmed a temperature ramp cycle using this system.

Here are some photos of my oven which my housemates dont seem to mind having in the house. Its just been switched on and thats why the temp is quite low.
011.jpg012.jpg013.jpg014.jpg

My oven is basically a poor mans version of Brent's fantastic chamber which you can see you youtube here

Seems that Brent is colour curing at 102F (34C) and 96%RH
Brent's set-points are consistent with these documents which I found online. here and here
Unfortunately my tobacco doesn't seem to be yellowing correctly.
Here are some photos. As you can see one leaf is nicely yellow, the other is greenish and another is green with brown spots.

015.jpg016.jpg

Those photos were taken after 3 days in the chamber (93% constant RH with temp ramp 75->102F @ 2F/hour, then maintain 102F)
Seems I'm doing something wrong here. Perhaps I picked some of it too early, or my soil nitrogen is too high? any suggestions appreciated.

Regards
Patrick
 

NewZealand

David Walker
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Its a bit of a leaky box and it vents through the gaps. I find that I'm having to add in quite a bit of water with the mister, say 1L over three days just to keep the RH at 93%. After the leaf is yellow I'm taking it out and hanging it in the conservatory which is hot and dry. That way the stems dry in 2 days. The leaf becomes a bit brittle, but I think I can re-humidify it leaf before attempting the 6 week fermentation process.

Just as a side note - I might have a look at soaking the leaves in baking soda solution before colour curing. According to this patent that speeds up the curing time and lowers the TSNA carcinogen content. Also blasting leaves in a microwave oven after colour curing (according to this patent) will kill the bacteria which produce carcinogenic N-nitroso amines.
 

NewZealand

David Walker
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Mar 10, 2016
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Points
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Location
Auckland, NZ
correction to my original post "Seems that Brent is colour curing at 102F (***38.8C****) and 96%RH" --- just a typo on the Celsius conversion.
 

NewZealand

David Walker
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Mar 10, 2016
Messages
4
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Location
Auckland, NZ
Just to show the temperature gradient is working. On the bottom line of the display the DC stands for "Duty Cycle" of the hot plate and humidifier respectively. After 9 hours the setpoints are close to targets. The set temperature is still increasing here which is why the actual temp is somewhat trailing the setpoint. I've upped the %RH on this batch to see if that makes any difference.
001.jpg
 
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