The Convection Thread

[Dan Morrison]

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]

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]

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]

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:

 

[Hippie Dickie]

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]

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.

 

[arb]

On the subject of absorption and kieff why does my first hit always obviously whitewall the piece yet have barely no visible vapor on exhale 4 seconds or so later?

 

[Dan Morrison]

@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?

 

[oldfool]

...would this method dominate over ground flower?

Grinding up our flower doesn't sound like the best idea to me.
I'm gonna try a new kind of grinder from Lift Innovations that cuts instead of grinds.

 

[MinnBobber]

Don’t be choppin those trichs
Vetus 72MZ ceramic tipped calyx liberator

 

[Shit Snacks]

@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]

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.

 

[Abysmal Vapor]

@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]

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.

@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]

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!

 

[Dan Morrison]

@cannasoor , EXACTLY.

 

[Dan Morrison]

After more testing and thinking on the ideas presented in this thread, I am really enjoying that idea of the trichome to leaf ratio.

Going back to previous posts, we described a coarse grind as having a higher ratio of trichomes compared to exposed inner plant material.

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

I'm going to shorten the above into:, High T:L, and Low T:L

I've been going back and forth between the two to really tease out the differences that I'm seeing. For a while there I was flip flopping between what ratio I liked most, but ultimately the coarse grind with a higher trichome to leaf ratio has emerged as a winner for me.

Here's some rough observations so far:

To get what I feel is the best coarse grind, I manually pull apart the flower in a fairly meticulous way. I have tested a bunch of little tools and I think some combination of razor sharp X-acto blade, ice-pick, and very fine tweezers is a good way to go. Magnification helped a lot as well.

I know this method is not viable for most people... for one.. it's just too time consuming... but for now I've accepted the practice. The right tools has helped to make it more enjoyable at least.

My only goal here is to expose as many trichomes as possible, while breaking the least amount of leaf. If a leaflet is too large to fit into the chamber without folding it, I'll cut it in half. Particle size varies wildly, I have large leaflets and small ones, doesnt matter.

I often find that leaflets need to be folded open to reveal trichomes hidden inside. Many times I encounter tight ball shaped leaf bundles about the size of a grain of rice, these also need to be teased open. The ball shapes are like unopened roses... and each of those petals inside has trichomes growing on their surface.

In the end your material should resemble tortilla chips, you shouldn't have any ball-shaped particles in there, only flat leaf-shaped things.

I'm always amazed at how much stem and other non-trichome laden parts of the flower I'm able to separate out.

Did I mention that this is very tedious?

So right off the bat this idea of reaching a high T:L presents a challenge. This, imo, is a good reason to look towards dry sift/kief as an alternative, more on that later.

-----

I try to have a very fluffy pack. I arrange each particle as if I want it to be suspended in space... barely touching the particles around it.

BUT, I'm also mindful to not go overboard here. If I leave too much air space, I do find that as the plant material shrinks after the first hit, you risk it all coming loose and just blowing around with too much air space in the chamber.

Usually just shoveling the material into the chamber and allowing it to settle naturaly without tamping is totally fine. The coarse material wants to remain fluffy!

-----

Weight vs. Volume.

A fine grind with low T:L will allow you to fit more weight of flower into a chamber compared to a coarse grind. This can give the illusion of greater vapor production and faster extraction with a fine grind.

I feel like this fact accounts for much of my flip flopping earlier on. I was comparing two chambers packed with the same volume of material... not the same weight.

Now, If I want to do a side by side comparison, I try to make sure I am comparing two chamber loads of the same weight, not the same volume. A coarse grind will occupy a MUCH larger space.

You can do a quick test by first filling your chamber full with fluffy coarse material. Now unload that material and chop it up finely with scissors. Re-load the finely ground material and note the drastic change in volume.

-----

The coarse material allows for a huge amount of air flow around all of the exposed trichomes.

I feel like I'm able to push more heat through the chamber quicker without hot spotting. This results in faster, more even, extraction.

Because of improved speed and efficiency, I think a high T:L is very well suited to one or two hit sessions without stirring.

If you lower the heat, you'll be able to get very clean hits and tease out all those flavors over a longer session if that's more your style.

-----

By maximizing the T:L, convection heat allows you to target the trichomes, and less of the volatiles held inside the plant material itself. In this way, convection heat can be selective in what it heats. I think this is an important difference compared to conduction.

-----

I think freshly made mid/low grades of dry sift is the ultimate expression of a high T:L.

I really wonder if it's economical to produce small amounts of dry sift at home using a mini tumbler. Perhaps only tumbling a few grams of flower at a time. @invertedisdead , any thoughts on that?

I'm imagining a small motorized tumbler the size of a beer can that you could run for a few hours inside the freezer to get maximum yield with minimum effort.

If the yield was high enough... could be a neat option.

Given the choice, I wonder if I would just vaporize dry sift all the time. Currently the availabilty of flower far outweighs the availabilty of dry sift in Canada.. so that's not really an option yet.

-----

Some bonus points I've noticed:

Coarse material clogs screens much slower.

Coarse material stays fluffy, where as fine grinds tend to shrink and compress after the first couple hits. I get the sense that good airflow is maintained throughout the entire session.

----

In summary:

A high Trichome to Leaf ratio is acheived through manually tearing apart flower.

High T:L gives more efficient extraction due to even airflow across trichome laden surfaces.

High T:L helps the convection heat to target only the trichomes, producing more tasty vapor.

---

All a work in progress! And just my personal preference.

 

[cx714]

I often find that leaflets need to be folded open to reveal trichomes hidden inside. Many times I encounter tight ball shaped leaf bundles about the size of a grain of rice, these also need to be teased open.

Did I mention that this is very tedious?

I'm imagining a small motorized tumbler the size of a beer can that you could run for a few hours inside the freezer to get maximum yield with minimum effort.

Please add me to the list!

 

[Dan Morrison]

Going deeper!

Here's a calyx from fresh to vaped. The length of this calyx is about 5mm. It's placed on top of a filter screen made from paper, just to cradle it and make for a nice white backdrop.

This was after three hits at a low/med temp.

It's neat to see that all the little trichomes either disappeared or shriveled up and turned dark brown in the ABV shot.

This is a complete enough extraction for me, and yet, the final ABV is still relatively light in color.

I'm not really sure what I learned here, but it's cool to look at, haha!

 

[GoldenBud]

Going deeper!

Here's a calyx from fresh to vaped. The length of this calyx is about 5mm. It's placed on top of a filter screen made from paper, just to cradle it and make for a nice white backdrop.

This was after three hits at a low/med temp.

It's neat to see that all the little trichomes either disappeared or shriveled up and turned dark brown in the ABV shot.

This is a complete enough extraction for me, and yet, the final ABV is still relatively light in color.

I'm not really sure what I learned here, but it's cool to look at, haha!

View attachment 11080

View attachment 11079

EDIT:
yeah that's the right way!!! the chlorophyll color didn't change much, so it's a vaporization process of like, oils only
the chlorophyll is just an organic non medicinal compound or even may be harmful to inhale because of -Mg/-N bonds?

 

[Dan Morrison]

@GoldenBud , I think that's the idea. Extract only the trichomes, leaving everything else alone. I'm sure there are a number of things other than just chlorophyll that can be omitted from the vapor stream.

It also depends on your personal preference. I think a lot of people like the thick robust vapor of a conduction vape... I don't think that there is anything wrong with that.

I think my reasoning behind wanting to stop the extraction at just the trichomes is that I like the taste and feel like the effects are there... so I don't really see a need to go further.

 

[Vaporware]

@Dan Morrison I’m assuming that was extracted in a Nomad? Do you know which heater you were using and roughly what the speed and length of your draws were?

It’s hard for me to tell when flower’s spent by looking at it due to color vision issues and it’s even harder when the AVB is light, but at some point it just stops producing much vapor even if it’s light. Continuing to push beyond that is mostly bad taste and not great effects in my experience.

It’s cool to see what’s actually going on in such detail!

 

[invertedisdead]

I really wonder if it's economical to produce small amounts of dry sift at home using a mini tumbler. Perhaps only tumbling a few grams of flower at a time. @invertedisdead , any thoughts on that?

I recently tried an idea I had for easier at home sifting - it didn’t work at all but I’m waiting on some new parts on the way to try it again.

A micro tumbler could be cool! Cold tumbling especially, though Ive noticed standard household freezers sometimes struggle to really get the flower frozen.

I didn’t like dry ice sift at all.

I was vaping straight sift bowls in the Alpha the other day with my little 14mm bowl. I think sift is fantastic, one of the absolute best possible cannabis experiences for me.

It sort of reminds of the differences between hash rosin vs flower rosin. Work put in upfront makes for a smoother, cleaner final vaping experience. I could see convection vaping sift in the same way. Think I’ll go load me one now and ponder on that!

 

[Roffa]

I bought a set up from @Vapolaborium with the new convection module and never looked back. Pure convection, drop in crumbled buds and that's it. My other main vaporizer is a Prrl Labs Neo, and an accompanying pipe: that one has radiant heat, the Vapolaborium is just pure convection.

 

[Dan Morrison]

@invertedisdead , Right on dude!

@Vaporware , Yep! But... I don't remember the exact parameters. It was the low heater, on a battery that was probably around 3.7v, and draw speed was slow. Probably somewhere around 10 second draws. I took a look at the chamber between hits, and didn't notice any difference with the naked eye between the first and second hit. So, I think the first hit was where all the extraction happened... the second two were just to make sure.

This test was more about wanting to see what fully extracted material might look like in macro view.

I popped in the low heater for this test because I really wanted to heat soak the chamber in a more delicate way. I suspected that I could fully extract the trichomes without having to heat the material so much that it turned brown. The low heater just allows for more control in these low/med temperature ranges.