Moist ideas :-)

If i take 100grams of fresh harvested bud and allow to dry for two weeks how do i work out at what the moisture content of the final dried bud is?

Buyyouabeer posted this in another thread (rep+)-

"The property of the air is called the equilibrium moisture content (EMC) and it is numerically equal to the MC that wood will achieve during drying if you wait long enough and if the conditions do not change. (Example: At 30% RH, wood will achieve 6% MC. So the air has an EMC of 6%.)

Common conversions:
0% RH = 0% MC = 0% EMC
30% = 6%
50% = 9%
65% = 12%
80% = 16%
99% = 28%"

Assuming wood weed food all have a similar scale we could simply jar our weed with a suspended hygrometer in air space and record the value of humidity when it no longer rises any higher. This value used in a table would suggest the moisture content percentage i.e. 10-15% for wood but i doubt more than a couple percent change if there were a table for mj or somthing of accurate representation.

If i couldnt record humidity how do i work out the final moisture content after two weeks hang drying of a fresh 100gram harvest?

Take an additional ten grams of fresh harvested bud and carefully heat in the correct matter to expunge all moisture then re weigh.

Multiply this dry weight by ten then subtract from the final two week dry harvest weight to leave the percentage moisture amount.

How do i dry 100grams of fresh harvested bud to a final moisture content of 15%?

Hangdry your bud in a ventilated drying space that maintains the corrosponding humidity of say the table above (ill pretend i did the maths) 72.5% and come back in two weeks - the bud should equalise to this point with a corrosponding value of 15% and litreature suggests any futher moisture loss past this will take a much longer period of time so it will stay at this and not loose much for longer periods if atmosphere kept exactly.

How do i maintain my bud moisture in a jar for periods of time say six months or a week, if you smoke far too much?

If we took the above bud at 15% and put enough in a jar so that it was reasonably full we would assume that as long as the humidity of the air was lower than the corrosponding equilibrium relative humidity it would raise the jars humidity up to the 72.5% as mentioned above (ya you got wet weed at this point). If the humidity on that day was higher then the bud would absorb some into its matrix but luckily were talking small amounts so not a great deal.of overall extra weight - Boveda anyone?

If we jar at lower humidity it would be safer and promote the dry a fraction more as it equalized - of course we could jar under a set humidity by humidifying or dehu. you packaging area/warehouse.

Obviously i aint got wood and this is theoretical. Dry time in a perfect environment is preferrably longer than shorter as equilibrium once reached dosent change much or fast.

Those who dry at low humidity experience the drier end than those at the higher relatve humidities - luckily all fall within woods smoking range so its more the detail as both higher and lower still produce a great dry end product.

This taken into account the utmost best way to produce the right rnvironment is to spend money and climate control not jar early as that encumbers the ability to loose moisture and equalize.

It begs the question if air dosent hold much weight in water just how much you loose by burping wet weed in a jar everyday cannot be even much worth note and possibly why if you jar weed to early you have to burp for what... two three weeks?

I never liked the burp, wet weed soon taste off or molds if left too long, dry then jar - i check its still dry the next few days and if it stays that way bingo jar sealed for a few months or however long.

Kingrow1 said:

If i take 100grams of fresh harvested bud and allow to dry for two weeks how do i work out at what the moisture content of the final dried bud is?

Buyyouabeer posted this in another thread (rep+)-

"The property of the air is called the equilibrium moisture content (EMC) and it is numerically equal to the MC that wood will achieve during drying if you wait long enough and if the conditions do not change. (Example: At 30% RH, wood will achieve 6% MC. So the air has an EMC of 6%.)

Common conversions:
0% RH = 0% MC = 0% EMC
30% = 6%
50% = 9%
65% = 12%
80% = 16%
99% = 28%"

Assuming wood weed food all have a similar scale we could simply jar our weed with a suspended hygrometer in air space and record the value of humidity when it no longer rises any higher. This value used in a table would suggest the moisture content percentage i.e. 10-15% for wood but i doubt more than a couple percent change if there were a table for mj or somthing of accurate representation.

If i couldnt record humidity how do i work out the final moisture content after two weeks hang drying of a fresh 100gram harvest?

Take an additional ten grams of fresh harvested bud and carefully heat in the correct matter to expunge all moisture then re weigh.

Multiply this dry weight by ten then subtract from the final two week dry harvest weight to leave the percentage moisture amount.

How do i dry 100grams of fresh harvested bud to a final moisture content of 15%?

Hangdry your bud in a ventilated drying space that maintains the corrosponding humidity of say the table above (ill pretend i did the maths) 72.5% and come back in two weeks - the bud should equalise to this point with a corrosponding value of 15% and litreature suggests any futher moisture loss past this will take a much longer period of time so it will stay at this and not loose much for longer periods if atmosphere kept exactly.

How do i maintain my bud moisture in a jar for periods of time say six months or a week, if you smoke far too much?

If we took the above bud at 15% and put enough in a jar so that it was reasonably full we would assume that as long as the humidity of the air was lower than the corrosponding equilibrium relative humidity it would raise the jars humidity up to the 72.5% as mentioned above (ya you got wet weed at this point). If the humidity on that day was higher then the bud would absorb some into its matrix but luckily were talking small amounts so not a great deal.of overall extra weight - Boveda anyone?

If we jar at lower humidity it would be safer and promote the dry a fraction more as it equalized - of course we could jar under a set humidity by humidifying or dehu. you packaging area/warehouse.

Obviously i aint got wood and this is theoretical. Dry time in a perfect environment is preferrably longer than shorter as equilibrium once reached dosent change much or fast.

Those who dry at low humidity experience the drier end than those at the higher relatve humidities - luckily all fall within woods smoking range so its more the detail as both higher and lower still produce a great dry end product.

This taken into account the utmost best way to produce the right rnvironment is to spend money and climate control not jar early as that encumbers the ability to loose moisture and equalize.

It begs the question if air dosent hold much weight in water just how much you loose by burping wet weed in a jar everyday cannot be even much worth note and possibly why if you jar weed to early you have to burp for what... two three weeks?

I never liked the burp, wet weed soon taste off or molds if left too long, dry then jar - i check its still dry the next few days and if it stays that way bingo jar sealed for a few months or however long.

Click to expand...

Adult A.D.D. much? Why over complicate the simple method of curing bud? Call me ole fashion or something but I hang dry, till dry enough. I go by feeling it with my fingers and a snap on small stem. My dry weight of wet bud always runs about 25%. Into jars burp and check once a day for a couple weeks. That's all I worry about. I have never used hydrometer or anything like that. I have never had a mold prob in jar in 5 years, since my first attempt. O.k. that's as long as a book as I can write.

Zephyrs said:

Adult A.D.D. much? Why over complicate the simple method of curing bud? Call me ole fashion or something but I hang dry, till dry enough. I go by feeling it with my fingers and a snap on small stem. My dry weight of wet bud always runs about 25%. Into jars burp and check once a day for a couple weeks. That's all I worry about. I have never used hydrometer or anything like that. I have never had a mold prob in jar in 5 years, since my first attempt. O.k. that's as long as a book as I can write.

Click to expand...

I think kg is evolving his position on this one a tad. He's a typically old fashioned grower.
The point I will add here relates back to a discussion he and I have in another thread.
The mass of water contained in air with a given rh at a given altitude will result in a different (lower mass of water in the same volume of air) at a higher altitude and same rh and temp. This results in an increases the water capacity of the air, ie. it can take on more mass of water given the same mass of air. This also relates how ppm concentrations in air vary at different barometric pressures (mg/m3 is the appropriate unit to use ppm is just an easier convention).

The efficacy of burping a jar that the bud is imparting a significant increase in rh (a few percent rise over an hour or two) is minal, the bud was too wet to jar.

KG, haven't read the whole post in detail, will get to it tho.

One other thing, I think we would be more accurate to compare the dew point of differnt drying environments not rh.

SSGrower said:

I think kg is evolving his position on this one a tad. He's a typically old fashioned grower.
The point I will add here relates back to a discussion he and I have in another thread.
The mass of water contained in air with a given rh at a given altitude will result in a different (lower mass of water in the same volume of air) at a higher altitude and same rh and temp. This results in an increases the water capacity of the air, ie. it can take on more mass of water given the same mass of air. This also relates how ppm concentrations in air vary at different barometric pressures (mg/m3 is the appropriate unit to use ppm is just an easier convention).

The efficacy of burping a jar that the bud is imparting a significant increase in rh (a few percent rise over an hour or two) is minal, the bud was too wet to jar.

KG, haven't read the whole post in detail, will get to it tho.

Click to expand...

I get what you and KG are getting at. It's clear you both are very passionate about the plant we all love to grow and consume. I also am driven to more knowledge about cannabis also, just in a different direction, I been concentrating on going all organic. Maybe what I was trying to say in last post was, it's not that I have a magic barometer or r/h gauge in my brain. But just used to my home climate and humidity, which I guess makes it easier for me. Now if I had to move to highlands of Colorado hypothetically, then Ya my chances of screwing up my cure would likely go up.

SSGrower said:

One other thing, I think we would be more accurate to compare the dew point of differnt drying environments not rh.

Click to expand...

Hmmm, i saw this mentioned in data i read but would that be much more accurate and worth the effort to get that accuracy?

There were plant moisture tests using dew point with a cooled mirror in sealed chamber but i forget how it related to the buds final moisture or even how to do it.

Original conversations on bud moisture that led to this -


https://www.rollitup.org/t/bud-moisture-for-perfect-bud.985842/page-6

Kingrow1 said:

Hmmm, i saw this mentioned in data i read but would that be much more accurate and worth the effort to get that accuracy?

There were plant moisture tests using dew point with a cooled mirror in sealed chamber but i forget how it related to the buds final moisture or even how to do it.

Click to expand...

I think it would allow a more apples to apples comparison. The dew point at facility x vs the dew point at facility y.
That way for instnce if you say it takes 2 weeks to dry and dew point ranged from one value to another, I could more easilly duplicte those results by maintaing that dew point range. Within a range of acctable tempartures would be the caveat.

Zephyrs said:

I get what you and KG are getting at. It's clear you both are very passionate about the plant we all love to grow and consume. I also am driven to more knowledge about cannabis also, just in a different direction, I been concentrating on going all organic. Maybe what I was trying to say in last post was, it's not that I have a magic barometer or r/h gauge in my brain. But just used to my home climate and humidity, which I guess makes it easier for me. Now if I had to move to highlands of Colorado hypothetically, then Ya my chances of screwing up my cure would likely go up.

Click to expand...

LOL. In in CO, 7700 feet elevation and I would say there are soe particular challenges.
But you hit on it. The oltimers will get a split in their lip, lick their finger stick it in the air and now exactly what to do without knowing what the actual value of rh, dew point, time of day, what brand of underwear the president wears, whatever.

SSGrower said:

LOL. In in CO, 7700 feet elevation and I would say there are soe particular challenges.
But you hit on it. The oltimers will get a split in their lip, lick their finger stick it in the air and now exactly what to do without knowing what the actual value of rh, dew point, time of day, what brand of underwear the president wears, whatever.

Click to expand...

?? Ok sure.

SSGrower said:

I think it would allow a more apples to apples comparison. The dew point at facility x vs the dew point at facility y.
That way for instnce if you say it takes 2 weeks to dry and dew point ranged from one value to another, I could more easilly duplicte those results by maintaing that dew point range. Within a range of acctable tempartures would be the caveat.

Click to expand...

The relevant data should be on the internet and then you need to do the maths but im guessing it wont be much different to sea level in the end.. percent change here and there.

No one is accurately testing their bud moisture i know off though as in real world we can just guess it from this data close enough.

This is more for those seeking an answer and to put the argument to bed on the right way to dry and cure not so much finer detail.


Sadly it dosent address temperature or altitude or other variables but is a workable proceedure badly needed on these boards to curtail the stupidity of jarring weed after five days and burping for three weeks

Kingrow1 said:

...snip...
Hangdry your bud in a ventilated drying space that maintains the corrosponding humidity of say the table above (ill pretend i did the maths) 72.5% and come back in two weeks -...snip...

Click to expand...

ROFLOL - I'll pretend I did the maths....

72.5 correlates with my real world experience in that once the bud stabilizes in the low 70's for rh, the bottom drops out, meaning the drying goes real quck.
This also goes with info in the noaa link I posted in that once fuel moisture contentent reaches 30%, changes in moisture content are almost exclusively dictated by the environment. The rate of change to equalibrium is determined primarily by the fuels diameter 1hr - grasses,10hr - finger size, 100hr - arm size, and 1000hr - leg size fuels, forrest floor duff is the collection of pine needels and other small diameter debris but due to the compact arrangment is generally considered a 100 hr fuel. Arrangment - bud compactness and diameter need to be considered if categorizing into the different fuel moisture groups.

Kingrow1 said:

The relevant data should be on the internet and then you need to do the maths but im guessing it wont be much different to sea level in the end.. percent change here and there.

No one is accurately testing their bud moisture i know off though as in real world we can just guess it from this data close enough.

This is more for those seeking an answer and to put the argument to bed on the right way to dry and cure not so much finer detail.


Sadly it dosent address temperature or altitude or other variables but is a workable proceedure badly needed on these boards to curtail the stupidity of jarring weed after five days and burping for three weeks

Click to expand...

The relavent data is contained within psychrometric tables that are written for each 500 feet of elevation change.

Jaring at 5 days, I might try it if I were drying a vac oven, but even if I had one I wouldnt be likely to do it.

Your write up here on drying ++ you wont get any more shit posting from me.







...(on this topic at least)

SSGrower said:

ROFLOL - I'll pretend I did the maths....

72.5 correlates with my real world experience in that once the bud stabilizes in the low 70's for rh, the bottom drops out, meaning the drying goes real quck.
This also goes with info in the noaa link I posted in that once fuel moisture contentent reaches 30%, changes in moisture content are almost exclusively dictated by the environment. The rate of change to equalibrium is determined primarily by the fuels diameter 1hr - grasses,10hr - finger size, 100hr - arm size, and 1000hr - leg size fuels, forrest floor duff is the collection of pine needels and other small diameter debris but due to the compact arrangment is generally considered a 100 hr fuel. Arrangment - bud compactness and diameter need to be considered if categorizing into the different fuel moisture groups.


The relavent data is contained within psychrometric tables that are written for each 500 feet of elevation change.

Jaring at 5 days, I might try it if I were drying a vac oven, but even if I had one I wouldnt be likely to do it.

Your write up here on drying ++ you wont get any more shit posting from me.






...(on this topic at least)

Click to expand...

One thing i had to do here was writeup so that most could understand - you need to show me what the percentage difference in bud with every 500ft of altitude is in its final dried moisture content is compared to sea level - is there even a correlation assuming temperature stays the same or im too dyslexic to comprehend and will remain on the side line till i am that bored i pick up stuff i never had time for before.

I showed some correlation to humidity and bud final dried moisture content - where does this stand with altitude is what were asking, we getting bone dry 0% moisture bud at 3000ft and 70% rh or is it 15% or what dude?

Intresting but i need easy to understand figures here soory

Kingrow1 said:

One thing i had to do here was writeup so that most could understand - you need to show me what the percentage difference in bud with every 500ft of altitude is in its final dried moisture content is compared to sea level - is there even a correlation assuming temperature stays the same or im too dyslexic to comprehend and will remain on the side line till i am that bored i pick up stuff i never had time for before.

I showed some correlation to humidity and bud final dried moisture content - where does this stand with altitude is what were asking, we getting bone dry 0% moisture bud at 3000ft and 70% rh or is it 15% or what dude?

Intresting but i need easy to understand figures here soory

Click to expand...

Elevation and barometric pressure are directly correlated, it is the principle most altimeters operate on.
barometric pressure is a driving force behind the weather we experience, and has direct impact on rh and dew point.

It wouldn't be bone dry at 70 rh and I would suppose that if it were truely equillabrated it would be in the ballpark of 15 pct moisture content.

I should not use the word equilibrated when describing how I dry, stabilize is probably a better word. The fan that runs when I want rh to drop will run about every 5 minutes until the bucket environment stabilizes. When the interval for the fan running is more than 15 min or so, I drop the rh setting. Towards the end tho I may only adjust 1 or 2 times a day and I'm not always around to babysit so eventually I'll write an arduino program to handle it. ideally tho, I think I'd want a room controled to 65% rh and 70 deg. F this would allow for better airflow which I think is important to the process too.

The thing is weather is never constant and one must maintain at least a casual observance of what is happening. It is much easier to control the environment when you know where the starting point is.

Next round I'm gonna look at weighing wet bud, the moisture meter I have for wood does not have a cannabis setting.

"The Bucket" method.
there's a reptile heat mat in the bottom of the bucket, and it can't get the temp to 75.

Sorry it blurry meters say 67 F, set point 75F, 37.5% rh, set point 52. It was at 51.5 rh when I pulled the lid to take pic, the lid was off for less than a minute. Chopped 3/8, another 3 days before jar. I target 50% rh for jar storage.

I get the sense there is some variance in the table you posted for rh/water content, my instinct says the moisture content numbers are a bit low for cannabis but idk. Maybe if I were to look at what the rh would be at altitude given an assumption those numbers are for sea level at 70F there would be more allignment with what I think I am observing?

How accurate does the answer need to be?

The following is probably wrong in some way:
Assume water content 85% (internet says 80-90% of plant matter is water)
85 g (water) / 100 g (fresh)
100 g (fresh weight) - (dry weight g) = water lost g
85 g (water) - water lost g = final water g
final water g / dry weight g = water content %

I feel like I'm missing something since the above doesn't mention humidity at all.

I've always wondered how labs dessicate samples for testing, without volatizing monoterps? They aren't using moisture testers, there's no means to do this on Cannabis as you could for lumber. They are simply drying samples to an arbitrary self-standardized number, you cant tell me volatiles aren't evaporated... And you cant tell me any random 2 labs will be using the same standard MC for analysis.

Are they catching volatiles and adding back to the equation? Otherwise it skews the results of everything, MC and all other relative weights. Lab testing for relative weights has become completely useless in my mind. What if a sample is dryer than their testing standard, do they remoisten it? Or does it automatically test higher?

SSGrower said:

One other thing, I think we would be more accurate to compare the dew point of differnt drying environments not rh.

Click to expand...

We don't use slang on grow forums anymore, its vpd sir.

LinguaPeel said:

I've always wondered how labs dessicate samples for testing, without volatizing monoterps? They aren't using moisture testers, there's no means to do this on Cannabis as you could for lumber. They are simply drying samples to an arbitrary self-standardized number, you cant tell me volatiles aren't evaporated... And you cant tell me any random 2 labs will be using the same standard MC for analysis.

Are they catching volatiles and adding back to the equation? Otherwise it skews the results of everything, MC and all other relative weights. Lab testing for relative weights has become completely useless in my mind. What if a sample is dryer than their testing standard, do they remoisten it? Or does it automatically test higher?

Click to expand...

No idea but a guess if you knew its dew point in a volume of air uou should know its exact water oercentage and thus dry weight.

Possibly by solven extraction then weighing the final weight of solvent after water is driven from it.

Idk just a guess

SSGrower said:

Elevation and barometric pressure are directly correlated, it is the principle most altimeters operate on.
barometric pressure is a driving force behind the weather we experience, and has direct impact on rh and dew point.

It wouldn't be bone dry at 70 rh and I would suppose that if it were truely equillabrated it would be in the ballpark of 15 pct moisture content.

I should not use the word equilibrated when describing how I dry, stabilize is probably a better word. The fan that runs when I want rh to drop will run about every 5 minutes until the bucket environment stabilizes. When the interval for the fan running is more than 15 min or so, I drop the rh setting. Towards the end tho I may only adjust 1 or 2 times a day and I'm not always around to babysit so eventually I'll write an arduino program to handle it. ideally tho, I think I'd want a room controled to 65% rh and 70 deg. F this would allow for better airflow which I think is important to the process too.

The thing is weather is never constant and one must maintain at least a casual observance of what is happening. It is much easier to control the environment when you know where the starting point is.

Next round I'm gonna look at weighing wet bud, the moisture meter I have for wood does not have a cannabis setting.

"The Bucket" method.
there's a reptile heat mat in the bottom of the bucket, and it can't get the temp to 75.
View attachment 4301223
Sorry it blurry meters say 67 F, set point 75F, 37.5% rh, set point 52. It was at 51.5 rh when I pulled the lid to take pic, the lid was off for less than a minute. Chopped 3/8, another 3 days before jar. I target 50% rh for jar storage.

I get the sense there is some variance in the table you posted for rh/water content, my instinct says the moisture content numbers are a bit low for cannabis but idk. Maybe if I were to look at what the rh would be at altitude given an assumption those numbers are for sea level at 70F there would be more allignment with what I think I am observing?

Click to expand...

Air exchange way more important than humidity to drying why bud still dries at 70%rh.

LinguaPeel said:

We don't use slang on grow forums anymore, its vpd sir.

Click to expand...

Kinda not relvent if the plant is dead?
Those are not slang terms in metrology