The Convection Thread

Dan Morrison

Well-Known Member
Manufacturer
I always said if Dry sift was more popular I would never grind again.

I like this idea. Do you find that a fiber medium is required to disperse the melting trichomes? I wonder if there is a pelletized/fiber medium with low density and thermal conductivity (carbon, perlite, hemp fiber) that could be mixed with dry lift to uniformly spread the tiny particles and expose the most surface area while maintaining good airflow.

I imagine 1mm dia. sized grains of a rough, inert, low density (and disposable!) material mixed with dry sift, coating each grain in a super thin layer.

Perhaps the same principle could be applied to whole flower that has been very finely ground and sieved. Though... the flavor profile would be totally different, having all that plant material in there.
 

arb

Semi shaved ape
We love vaporizing kieff roughly 7mm layer scoopped,tapped to settle and much nicer than dabbing in our opinion.
Conduction seems to make the taste go sour very fast whereas convection the taste seems to just fade after a coup!e hits.
No qtip necessary so it also appeals to my lazy and cheap.
😂
 

invertedisdead

Weapons of VAS Destruction
Do you find that a fiber medium is required to disperse the melting trichomes?
Using sift by itself needs a pretty fine screen but I tend to find you can make use of the plants own cellulose fibers present in the dry sift to keep the oils wicked. This is one of those cases where you really don’t want the highest grade sift. Something middle of the road will give you all the benefits and still handle easily, something super high grade would melt through or be more likely to clump in storage which we don’t really want as vaping pressed hash is kind of tricky.

Commercially you could cold tumble plant material, and if you really wanted consistency you could filter with an air jet sieve to the desired micron size. I’ve got a few designs for a small personal cold sifter for doing this at home that was inspired by a way to improve my home rosin without the arduous bubble hash process.


roughly 7mm layer
I like the sound of that!! 😊😊😊
 

Farid

Well-Known Member
The way I convection vaporize dry sift is to put the sift in the center of the screen, leaving the edges of the screen open to allow airflow when the sift melts. Like in this picture, but with a vaporizer not a bowl:

2789-HD_SBUBB.jpg
 
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Hippie Dickie

The Herbal Cube
Manufacturer
If you hover a q tip in the oven tube while at your set temp, without the vial inserted, will it brown from radiant heat without touching anything?
good question! i just tried this for a full 7.5 minute session ... no detectable color change for Qtip and not even warm.

This does remind me that after about 1 minute from start up there will be thin wisps of vapor rising from the vial - terpenes, i guess - lower temp volatiles. also just remembered than when i put a BBQ thermometer probe in the middle of the herb in the vial, the resting temp is about 50°F below setpoint, and rises to setpoint with a draw - but i need to redo that test to reverify the numbers someday - not doing much with the cube these days, i've been distracted.

so, bottom line, the radiant heat is way below the heater temperature - i was wrong about that in the post above.
 

GoldenBud

Well-Known Member
fine grind works well on 19mm devices as long as you give it a small stab in the center of the bowl, because as you said -- fine grind can cause the airflow to uneven cook it
your beautiful Nomad line - Dan - is 14mm right? try stab it or so, it may works pretty well with 14mm devices!
it's easier to pinch it on a WPA because of the gravity hehe, but.. i find the results much better. never had a coarse grinder and I'm waiting to try it too.
 

Dan Morrison

Well-Known Member
Manufacturer
@invertedisdead That sounds awesome man! Thanks for sharing your technique.

I like the simplicity of not adding any foreign media (hemp fiber, cotton, mesh, etc.) to help disperse the trichomes...but rather, like you said, allow the plant material itself to be the 'wick'.

I suppose, if you had too-high of a grade of dry sift you could add back finely ground flower that has been sifted into uniform particle sizes, shooting for the least amount of flower needed to give proper airflow.

____

I like the idea of trichome to leaf ratio.

Unless you like the more earthy flavors of vaporizing plant material, I'd assume that you would want a higher trichome to leaf ratio.

And I guess you could achieve this in two ways. 1. Physically having more trichomes in the chamber, 2. Using a coarser grind to expose less of the inner plant material to the hot air flow.

I think you can assume that the finer the grind, the more inner leaf material is exposed. And conversely the coarser the grind, the less inner leaf material is exposed.

So:

Coarse = High trichome to leaf ratio.
Fine = High leaf to trichome ratio.

____

Perhaps this is all getting off the rails, haha! But when you follow the theoretical path it does seem to me that if our goal is to heat, by convection only, those tiny trichomes.... it would be better to uniformly suspend those trichomes in a matrix that allows even airflow over every trichome particle.

When you look at a close up image of these trichomes, they do seem evenly spaced on the surface of the leaf/calyx. Almost as if they were prepared by nature for our consumption!

The problem is that these trichomes are often trapped inside of plant material, due to natural flower density or compression during processing/storage.

So the issue is how do you easily achieve a higher trichome to leaf ratio. Perhaps the best IS to dry sift... or maybe pull apart the flower with tweezers.... I'm not sure.

I think this helps to explain why coarse grinds give a flavor profile that is perhaps more like a pure dry sift flavor profile.

Looking back,

Yeah I have noticed this as well, particularly with a whole nug, where I will take one hit at higher temp than I would normally start at, then flip the nug to take another, then break it up... The spectrum of flavors is a totally different experience and honestly even the effects sometimes... Even a chunky coarse grind is not quite the same!

I've noticed the same with whole flower, and I seem to remember that vaporizing whole flower was a bit of a thing here on the FC a while back....

Seeing as the whole flower would have the highest trichome to leaf ratio exposed to the hot air flow, it seems like this would be the closest thing to vaporizing dry sift.

It makes me wonder if dry sift is an improved method... and if we had an easier way to produce dry sift...would this method dominate over ground flower?

Or perhaps it's more than just the trichomes. Is there something in the leaf itself that is worth vaporizing. Are those flavors important? Even if they don't add any psychoactive compounds to the vapor?
 

Shit Snacks

Milaana. Lana. LANA. LAANAAAAAAA
@invertedisdead That sounds awesome man! Thanks for sharing your technique.

I like the simplicity of not adding any foreign media (hemp fiber, cotton, mesh, etc.) to help disperse the trichomes...but rather, like you said, allow the plant material itself to be the 'wick'.

I suppose, if you had too-high of a grade of dry sift you could add back finely ground flower that has been sifted into uniform particle sizes, shooting for the least amount of flower needed to give proper airflow.

____

I like the idea of trichome to leaf ratio.

Unless you like the more earthy flavors of vaporizing plant material, I'd assume that you would want a higher trichome to leaf ratio.

And I guess you could achieve this in two ways. 1. Physically having more trichomes in the chamber, 2. Using a coarser grind to expose less of the inner plant material to the hot air flow.

I think you can assume that the finer the grind, the more inner leaf material is exposed. And conversely the coarser the grind, the less inner leaf material is exposed.

So:

Coarse = High trichome to leaf ratio.
Fine = High leaf to trichome ratio.

____

Perhaps this is all getting off the rails, haha! But when you follow the theoretical path it does seem to me that if our goal is to heat, by convection only, those tiny trichomes.... it would be better to uniformly suspend those trichomes in a matrix that allows even airflow over every trichome particle.

When you look at a close up image of these trichomes, they do seem evenly spaced on the surface of the leaf/calyx. Almost as if they were prepared by nature for our consumption!

The problem is that these trichomes are often trapped inside of plant material, due to natural flower density or compression during processing/storage.

So the issue is how do you easily achieve a higher trichome to leaf ratio. Perhaps the best IS to dry sift... or maybe pull apart the flower with tweezers.... I'm not sure.

I think this helps to explain why coarse grinds give a flavor profile that is perhaps more like a pure dry sift flavor profile.

Looking back,



I've noticed the same with whole flower, and I seem to remember that vaporizing whole flower was a bit of a thing here on the FC a while back....

Seeing as the whole flower would have the highest trichome to leaf ratio exposed to the hot air flow, it seems like this would be the closest thing to vaporizing dry sift.

It makes me wonder if dry sift is an improved method... and if we had an easier way to produce dry sift...would this method dominate over ground flower?

Or perhaps it's more than just the trichomes. Is there something in the leaf itself that is worth vaporizing. Are those flavors important? Even if they don't add any psychoactive compounds to the vapor?

I love the way you broke this down, the distinction is simple!

Yeah the thing is, I don't always want one or the other, of course it depends on the vape, but also the specific situation, and general consistency of the nugs: the structure moisture density etc...

To extract more fully I am often breaking down further if I start with hand broken chunks, and those later hits taste even worse I guess? That's the trade off when you get more is a good flavor in the beginning you get less the end... So when you grind it up consistently, you get a more even extraction and control the flavor, still not going to taste good at the end but somehow it is better, and yeah same thing if you were temp stepping milk in lower times then you're going to get less and worse flavor at the higher temps... There is appeal to just extracting enough for flavor only, but there is a lot of value in that in between area.

So everything is a trade-off, and I think it may be tough to have a universal, even for one type of extraction style?
 

Farid

Well-Known Member
To add to what @Shit Snacks is saying regarding the tradeoff between flavor and complete extraction I see a lot of similarities with the coffee analogy again.

With coffee we brew with flavor in mind. Unless you're out in the boonies and forced to ration your beans, most people are not brewing in a manner to get the most coffee possible per gram of beans. If we were, we'd be grinding as fine as possible, and doing multiple infusions of water, getting a series of decreasing quality cups.

I think getting everything out of cannabis is a holdout from prohibition to a certain extent. Once I started growing I stopped saving vaped bud because I just didn't see the point. Similarly I stop vaping a bowl when the flavor goes bad, even if there is still a hit left in it. Since cannabis costs so little, I don't feel the need to get every drop of actives.

That said, I'm not a flavor chaser, and I don't temp step. I'm a 1 hit and done kind of smoker, and so I want that one hit to have great flavor as well as well rounded effects. Often I find this means bringing the bud I'm using to a point where there is not much left in it when that hit is done. So tiny bowls taken to their end.

One of the challenges in designing a dry herb vape is that every user is unique. So trying to characterize the "perfect" convection hit is really impossible. The one thing I think we all can agree on, however, is that combustion in a vape is failure. With airflow being such an important variable in convention, I think avoiding combustion is the place where the most innovation can occur.
 
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Abysmal Vapor

Saturnine in my mind
@Farid I totally agree that combustion is a failure , overcooking is just partial failure ,lol . One of the things i am so happy about my concepts is that the heater temp and air temp is no more than 30 C ,in other words it cannot combust ,because the heater itself runs at temps below combustion :)).
It is fairly easy to combust when your heating element is glowing ,you just need to decrease your draw,which can happen not only by choice,but due to blocked airflow. :))
 

Dan Morrison

Well-Known Member
Manufacturer
To add to what @Shit Snacks is saying regarding the tradeoff between flavor and complete extraction I see a lot of similarities with the coffee analogy again.

With coffee we brew with flavor in mind. Unless you're out in the boonies and forced to ration your beans, most people are not brewing in a manner to get the most coffee possible per gram of beans. If we were, we'd be grinding as fine as possible, and doing multiple infusions of water, getting a series of decreasing quality cups.

I think getting everything out of cannabis is a holdout from prohibition to a certain extent. Once I started growing I stopped saving vaped bud because I just didn't see the point. Similarly I stop vaping a bowl when the flavor goes bad, even if there is still a hit left in it. Since cannabis costs so little, I don't feel the need to get every drop of actives.

That said, I'm not a flavor chaser, and I don't temp step. I'm a 1 hit and done kind of smoker, and so I want that one hit to have great flavor as well as well rounded effects. Often I find this means bringing the bud I'm using to a point where there is not much left in it when that hit is done. So tiny bowls taken to their end.

One of the challenges in designing a dry herb vape is that every user is unique. So trying to characterize the "perfect" convection hit is really impossible. The one thing I think we all can agree on, however, is that combustion in a vape is failure. With airflow being such an important variable in convention, I think avoiding combustion is the place where the most innovation can occur.

Agree on all fronts. I think that in the future most people will settle on this style of vaporizing, where the level of extraction leans more towards flavor, while still getting most of the effects. I think you get really diminishing returns from those last couple hits.

I think that a convection vaporizer should be able to reach this adequately complete level of extraction in one or two hits.

This type of session really needs all of the variables to come together, the heat delivery, grind size, chamber size, etc... It's the most demanding type of session. If any of the variables are off, you'll get uneven/incomplete extraction. Drawing a session out over 5 or more hits will allow you to be a little more sloppy with both the vaporizer design and the setup.

You're so right about every user being unique.

I would go as far as saying overcooking is a failure. But then again... there are people out there who prefer those toasty flavors... so what do I know?

I think that this thread is less about defining the variables for THE perfect convection hit... but rather, defining what is needed to achieve whatever type of convection hit you're looking for.

For example, Lets say you wanted a 2 hit extraction with a 1:1 chamber diameter to depth ratio. Well then you could give the suggestion of:
- Medium Grind
- No tamping
- 330 degree air at chamber inlet
- 15 second 1st inhale
- 20 second 2nd inhale

Now, I know those variables may not be correct... but it would be cool if, in the future, we could have compiled enough data to say that set of instructions would give you the greatest chances of success.

Mind you... this also relies on your vaporizer being able to deliver the heat perfectly, or else that variable will always be in question.. but eventually we will get there, and with some desktops we are there already.

For now I feel like convection technique is in the wild west phase, It honestly feels like everyone has their own preferences. I'm actually not sure if this has more to do with the differences in personal taste or vaporizer design.

Perhaps this is how people felt in the early days of espresso, when the variables were unknown. But now that every which way of brewing has been explored... It seems like you can get very clear suggestions on how to set up each variable to achieve the result you're looking for.

I wonder how far we are from that?

What I would love to do is make a test rig. A plug in desktop that has enough thermal mass to give super consistent heat delivery. Perhaps outfit the entire rig with temperature probes for recording data. Air pump to eliminate the variable of lung control.

And then photograph the herb chamber after X amount of hits, at X temperature, and X grind setting. Compare results.

I bet a rig like that could come to some interesting conclusions. :sherlock:

@Abysmal Vapor That's the right idea for sure. I have always thought that the optimal heater design needs to have as much surface area as possible so that you can keep the heater temp as low as you can.
 

cannasoor

Well-Known Member
I'm also seeing that there are a number of us who 'tweezer' pick apart our herbs, trying to maintain the natural plant structure. I think that this is definitely worth looking closer at. How to maintain structure and create a uniform particle size with the least amount of effort.

In my late-night, cannabis-fueled deliriums … it's far in the future and I have a small horde of tiny nano-machines, sort of shear-shaped, that descend on the herb in the chamber, pre-firing, and trim it up into optimally-sized and shaped particles, then arrange them according to carefully calculated airflow patterns, and finally scoot out of the way as the firing occurs, and almost every molecule is optimally utilized, while the nanites observe and fold the data into the bespoke molecular-consumption machine-learning algorithm for the next nearly-optimal, microscopically-arranged hit.

Remember: Every Trichome Is Sacred!
 
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