Demystifying Flavour Production in RBA's

In simple terms, I personally get the best flavour from my Fishbone RDA on a mech mod, with a usual 24 G, SSteel, 6 to 7 wraps, 0.3 Ohm, with "Cotton Bacon V2" wick.

It's rather surprising as the FBONE is such a simple device with no airflow control, unlike more technically advanced RDA'S with which one would expect better flavour production.

Perhaps a fluke?

BTW "Cotton Bacon V2." is matchless for handling and flavour. I have tried a few other cottons, no names mentioned, and there is a definite flavour difference. I won't use anything else.

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Kendo tastes like popcorn. There I said it lol.
 
On the kendo cotton I find it disagreeable at low wattages. It only seems to become decent at high watts.

Anyways I find that the best flavour in relation to builds is in fact airflow.
Let me explain, the coil and cotton are to be personal preferences and wicking is largely determined by what setup is being worked with and where the juice well is our the juice holes sit.
What I'm saying is that all coils in escence do the same thing, vaporise liquid.
This is where airflow comes in. Airflow for one allows you to breath in as closing the airhole you cannot really vape. I get the best flavour by positioning the coils in such a way that airflow hits the underside and side of the coil. I suspect the cooling off the coil as air flows under it keeps it cool and delivers that flavour carrying vapour to your mouth. If the airflow is above the coil it's generally air you are suckling in with excess vapour.

Think of it like a air duct that you don't want to close off with a coil instead you want the direct air to interact with the coil on at least 2 sides before it interacts with your mouth as opposed to blocking the direct flow or not bring in line with the direct flow. If the airflow interacts with coil and then say a metal piece like the centre posts you kind of lose the direct flow.
I think the small attys do a consistently better job because the chamber is restricted and there is less distance to travel before the airflow does something else or interacts with something else.
Using a Moradin tank and the internals (chamber) are ceramic and there is a noticeable difference in taste as the airflow is not interacting with metal but a different material which has different heat properties as opposed to metal. Chamber is similar to the griffin.
 
For me the smaller chamber size atty with a drip tip to match the airflow size works best for my slow long draws. Coil placement and wick material plays a big part and has to be experimented with to find the best for your adv juices. There is a lot of planting potatoes 5min past midnight in the world of next Thursday so try what others recommend and find that magic vape for yourself. I don't think there is a one size fits all in vaping and the experimentation is part of the fun.
 
Small chamber atties like the Divo, Cyclone and Hornet are really my bag on the REO's and I do get flavour from them all... but for me personally I find that the wicking material makes a huge difference... I far prefer Rayon by a country mile and it really makes a difference to me with my menthols. That being said both my Supreme and Gemini RTA are wicked with Bacon Cotton and after a few toots the cotton taste goes and the flavour is still good... but when I rewick I will rewick them with Rayon.
 
Not really RBA related, but it is flavour and performance related.

I think I've figured out why Scottish Roll style wicking works so well in drippers.

It kinda forces you to put more cotton in the coil. I did a build earlier today, 10 Wraps of 24G with a 3.5mm ID per coil. Nothing to extraordinary but when it came time to wick, I used a crap load of cotton, it was so tight i had to hold the coils, to prevent them getting bent out of shape as I pulled the cotton through.

I just used regular strips of Muji Japanese cotton without peeling the edges off, I gently rolled each strip in my hands to get it round. and then I stuffed it in my coils :p

So far it's been performing crazy good, and it doesn't have that drop in flavour like you get with a scottish roll after 10 or so hits without redripping.

Here's a video of a guy doing this wicking. He calls it a Sushi Roll :p

He keeps saying Swedish... He means Scottish...

 
On general flavour, I've found for me, what matters more than chamber size, is air pressure on the coil. anything that has an airflow setup that allows for your coils to be crazy close to the airflow (Sapor RDA, Origen Genesis V2 MK2), tends to give me the best flavour.
 
A few two cents...

I agree with most of the comments above. I want to add a little bit of chemistry to the mix though. This is another technical discussion - its becoming a bad habit of mine, so after this one I'll try to chill it for a while as I'm starting to sound like a douche!

First of all, wicking. In terms of material, wicking can definitely change the taste. On the one hand, the wicking speed can have an influence on the amount of ejuice which can coat a coil at any instant - which will affect how much ejuice is vaporized. On the other hand, wicking material can form side reactions with ejuice components. Practically speaking, this will usually result in ejuice components being retained on the wick material instead of vaporizing. When your wick gets old, what I suspect is mostly happening is that more of the wick surface has reacted with ejuice components, which themselves can react with other ejuice components, giving a compounded result - usually, once a wick starts going bad, it gets even worse at a much faster pace. When a wick starts to singe, I'm guessing it starts to activate (open up binding sites) on some of the backbones (usually carbon) of the material - which will even further increase the reactivity of the wick.
Certain jucies - usually the darker ones, or ones with a significant sucrose content - reacts much faster with the wick, and again, this leads to decreased flavour much quicker, even when you use a more neutral juice afterwards.
Different materials will react with ejuice components a different paces. The effect can be very subtle - it might start reducing the flavour from the very beginning.
And of course, the actual taste of the wick can override certain flavours...
Interestingly, my hypothesis would be that wicks with higher silicon content will have longer longetivity... but I've only used organic cotton, so I have no real experience here.

The amount of wick have an effect on the internal airflow of the chamber, which I will address in a minute.

Next up is flavour perception. I think a bit of a common misconception that I've noticed is that flavour perception is based on the volume of flavour molecules present. This is indeed not the case - it is a factor of relative concentration. As long as the volume is large enough to sufficiently cover your tongue (and allow for evaporation throughout your entire olfactory system), the only difference in flavour perception will be a result of the concentration within your mouth. For instance, a big gulp of Coke won't taste more "Cokey" than a decent sized sip. The flavour concentration of the coke remains the same irrespective of the amount you drink.
In terms of vape, the flavour that you taste is relative to the other components - VG, PG and nic. If you build your atty in such a way that you vaporize PG and VG quicker than the flavour molecules, you'll get reduced flavour, and vice versa. Cloud chasers tends to maximize the tempo at which VG is vaporized, and when done correctly, will usually result in considerbly reduced flavour. On the other hand, it is possible to have a very flavourful vape even with very small clouds - which means that the flavour molecules is vaporized at a relatively faster rate than VG or PG, giving increased flavour concentration in your mouth, even though the total volume of the vape is quite small.

The question then is, how do the different factors of vaporizing ejuice affect the relative rates of ejuice vaporization? Heuristically, we know that a small chamber tends to give better flavour. Translating this into concentration and vaporization rates, it means a small chamber will usually vaporize flavour molecules at a relatively faster rate than the base liquid. To understand why, we must first discuss how heat affects different rates of evaporation.

As a suitable metaphor, consider how distillation works. When we distil a base liquid (lets say malted + fermented barley, since that will give us whiskey and whiskey is awesome), we first heat the liquid to ~60 deg C, where methanol starts to evaporate, and keep it there for a while will the methanol boils out. Next, we'll heat the liquid to ~78 deg C, where ethanol starts to evaporate, and keep it there for a while as we collect the ethanol. Finally, we selectively heat our base mixture (now devoid of methanol and ethanol) to higher temperatures in order to capture select flavour notes, which tends to have higher boiling points.
However, what would've happened if we skipped the first step, and heated directly at 78 deg C? At this temperature, the rate of evaporation for methanol will be the highest, followed by ethanol, whereas the rate of evaporation for any flavour compounds will be next to zero. If we collect the distillate at this temperature, we would get a high concentration of methanol and slightly lower concentration of ethanol, and no flavour. In the same line of thinking, if we heat directly to ~120 deg C, we would get pretty much the same concentrations in the distillate as what was in the base liquid.
Lastly, the relative concentration in the base liquid will also play a big role in determining the final concentration of the distillate. If we have 10 ml ethanol in 90 ml water, if we distil at exactly 78.37 deg C, the efficiency of evaporation for ethanol might be 100 % (meaning we are getting all 10 ml ehtanol) but the efficiency of evaporation for water might be ~40 % (meaning we are getting 40 % of 90 ml water = 36 ml water), giving us a final distillate of 21% ethanol. On the other hand, if we have 90 ml ethanol in 10 ml water, we are getting 100 % ethanol (90 ml) and 40 % water (4 ml) giving us a final distillate of 96%. The point of all of this is to illustrate that, distilling (or vaping) at the correct temperature still gives a distribution of all compounds in the base mixture.

How does this relate to vaping and flavour production? The boiling point of PG is 188.2 deg C and VG is 290 deg C. While boiling point is not the same as evaporation point, it will give us a good indication. The boiling point of the flavour components is unknown, since it depends on each mix and the flavour companies generally does not disclose this, and their chemistries change when steeped, but for the sake of argument lets say it is 250 deg C - somewhere between PG and VG. So what happens when we start vaping at a low wattage/temperature and slowly make our way up?
At low temperature, we are getting mostly PG. At slightly higher temperature, we are getting PG, some flavour, and a little VG. Even higher, and we are getting max PG, max flavour, and some VG. Finally, very high and we are getting max of everything. Now of course, max PG and VG in a 70:30 mix is 70% VG and 30 % PG. So even a little VG at lower temperatures might still be more than PG and flavour combined. Therefore, to get the most flavour concentration, we must work towards a very specific sweet spot (which will be different for each juice as well) - where the flavour evaporates at its maximum but with as little PG/VG evaporation as possible. (On the other hand, for cloud blowing we just want to go as high as possible, since we want as much VG to evaporate). When going higher than this sweet spot, we are getting the same number of flavour molecules, but at a lower concentration due to increased PG/VG evaporation - giving us less perceived flavour.

Lastly, unlike PG and VG, flavour molecules can undergo side-reactions at higher temperatures (usually denaturing into smaller chemical building blocks), which will reduce the perceived flavour. In the best case, it means you lose some complexity (as that wonderful strawberry and mint adduct breaks apart to give separate strawberry and mint perceptions); in the worst case, a flavour molecule denatures to the point where your senses cannot recognize it anymore.

All of the above points to the fact that mixologists very often give a perfect temperature for their mixes - anything below, and you're not vaporizing enough flavour molecules, and anything above you're reducing the final flavour concentration due to increased base liquid vaporization, flavour degradation or unwanted juice tones developing.


So... the actual temperature of your coil as it vapes is determined by many other things (see my previous wall of text, http://www.ecigssa.co.za/some-scien...ling-in-an-atomizer-evaluation-metric.t21258/). But given the same coil, wick and power in two different attys, the determining factor will be airflow. And more specifically, the velocity and amount of air on your coil directly (in other words, air pressure). In my previous post I talked about the equilibrium temperature - which is the temperature at which your coil is actually vaporizing ejuice, given the atty setup in terms of direct airflow on the coil. This equilibrium temperature must be at the flavour sweet spot to maximize flavour concentration. Anything higher or lower will reduce the overall flavour concentration. And unfortunately, temp control will create an artificial temperature - not the actual equilibrium temperature.

I hope this helps towards 'demystifying flavour production'. I know I haven't given any answers as to why smaller chamber attys give better flavour, or how coil positioning affects the science of it all... but I think you can rationalize mostly everything by thinking in the above terms (in terms of coil cooling and equilibrium temperature). If you're atty is currently vaping above the flavour sweet spot, you need to build in a way to reduce the temperature on the coil - in other words, more direct airflow on the coil, and vice versa if you're atty is below the flavour sweet spot. Finally, any change within the atty can be rationalized in this direction. For instance, increasing the wicking material (especially outside of the coil) can have big, usually negative, effects on the airflow. However, in the same vein, it can actually increase the air pressure on the coil even if it reduces the overall airflow, thereby increasing the cooling on the coil.

In terms of the smaller atty sizes: My personal guess (but it is only that) is that smaller chamber attys have, on average, the correct internal airflow for average builds in order to hit the flavour sweet spot. For instance, I've tried building crazier builds on my Goblin Mini, but I always go back to a more or less average build, as I've found that it always gives me better flavour. On the other hand, I've gotten great flavour from bigger attys - but I had to use more intricate builds. A triple-twisted single coil on a Smok TFV4 gives fantastic flavour, but is rubbish in the Goblin. On the other hand, two dual micro-coils on a Goblin is wonderful, but mostly just fog on a TFV4.

Final point, is that most attys can produce fantastic flavour, but you have to coax it from them. Smaller chamber attys tend to be easier to build for flavour.

Wall of text over... and I promise it will be my last one for a while! Takes too much time to read yo, which means very few people actually challenge some of the ridiculous statements I so often make!
 
I still battle to divorce flavour concentration from vapour concentration. More air, both should be less concentrated.

Airflow and chamber size: If droplets exist in the vapour - which is what I mean by spitback - flavour will be percieved as more intense.

Small chamber, short chimney/driptip, pretty sure droplets hit the mouth, even if not felt.

Larger chamber, maybe droplets fall back more. Which leads to airflow. If airflow is large and open, the draw upwards in the chamber lower in velocity than smaller airflow with a stronger draw, a faster jet stream? Carrying more droplets higher.

Howzat sound?

Re power. I vape currently TC, at a specific temp. I vary this as the mood hits. So whether I'm vaping at 30W or 80W the only difference should be the ramp-up time? Cannot see how that changes flavour really.

I'm trying to understand how it works so I can translate that to any tank.

I actually think you might be onto to something here as well. Taking into account that all vape is droplets of varying sizes though - otherwise it wouldn't be foggy at all. But maybe try to think in what causes larger or smaller droplets, and how the droplet size will impact taste?
 
A few two cents...

I agree with most of the comments above. I want to add a little bit of chemistry to the mix though. This is another technical discussion - its becoming a bad habit of mine, so after this one I'll try to chill it for a while as I'm starting to sound like a douche!

First of all, wicking. In terms of material, wicking can definitely change the taste. On the one hand, the wicking speed can have an influence on the amount of ejuice which can coat a coil at any instant - which will affect how much ejuice is vaporized. On the other hand, wicking material can form side reactions with ejuice components. Practically speaking, this will usually result in ejuice components being retained on the wick material instead of vaporizing. When your wick gets old, what I suspect is mostly happening is that more of the wick surface has reacted with ejuice components, which themselves can react with other ejuice components, giving a compounded result - usually, once a wick starts going bad, it gets even worse at a much faster pace. When a wick starts to singe, I'm guessing it starts to activate (open up binding sites) on some of the backbones (usually carbon) of the material - which will even further increase the reactivity of the wick.
Certain jucies - usually the darker ones, or ones with a significant sucrose content - reacts much faster with the wick, and again, this leads to decreased flavour much quicker, even when you use a more neutral juice afterwards.
Different materials will react with ejuice components a different paces. The effect can be very subtle - it might start reducing the flavour from the very beginning.
And of course, the actual taste of the wick can override certain flavours...
Interestingly, my hypothesis would be that wicks with higher silicon content will have longer longetivity... but I've only used organic cotton, so I have no real experience here.

The amount of wick have an effect on the internal airflow of the chamber, which I will address in a minute.

Next up is flavour perception. I think a bit of a common misconception that I've noticed is that flavour perception is based on the volume of flavour molecules present. This is indeed not the case - it is a factor of relative concentration. As long as the volume is large enough to sufficiently cover your tongue (and allow for evaporation throughout your entire olfactory system), the only difference in flavour perception will be a result of the concentration within your mouth. For instance, a big gulp of Coke won't taste more "Cokey" than a decent sized sip. The flavour concentration of the coke remains the same irrespective of the amount you drink.
In terms of vape, the flavour that you taste is relative to the other components - VG, PG and nic. If you build your atty in such a way that you vaporize PG and VG quicker than the flavour molecules, you'll get reduced flavour, and vice versa. Cloud chasers tends to maximize the tempo at which VG is vaporized, and when done correctly, will usually result in considerbly reduced flavour. On the other hand, it is possible to have a very flavourful vape even with very small clouds - which means that the flavour molecules is vaporized at a relatively faster rate than VG or PG, giving increased flavour concentration in your mouth, even though the total volume of the vape is quite small.

The question then is, how do the different factors of vaporizing ejuice affect the relative rates of ejuice vaporization? Heuristically, we know that a small chamber tends to give better flavour. Translating this into concentration and vaporization rates, it means a small chamber will usually vaporize flavour molecules at a relatively faster rate than the base liquid. To understand why, we must first discuss how heat affects different rates of evaporation.

As a suitable metaphor, consider how distillation works. When we distil a base liquid (lets say malted + fermented barley, since that will give us whiskey and whiskey is awesome), we first heat the liquid to ~60 deg C, where methanol starts to evaporate, and keep it there for a while will the methanol boils out. Next, we'll heat the liquid to ~78 deg C, where ethanol starts to evaporate, and keep it there for a while as we collect the ethanol. Finally, we selectively heat our base mixture (now devoid of methanol and ethanol) to higher temperatures in order to capture select flavour notes, which tends to have higher boiling points.
However, what would've happened if we skipped the first step, and heated directly at 78 deg C? At this temperature, the rate of evaporation for methanol will be the highest, followed by ethanol, whereas the rate of evaporation for any flavour compounds will be next to zero. If we collect the distillate at this temperature, we would get a high concentration of methanol and slightly lower concentration of ethanol, and no flavour. In the same line of thinking, if we heat directly to ~120 deg C, we would get pretty much the same concentrations in the distillate as what was in the base liquid.
Lastly, the relative concentration in the base liquid will also play a big role in determining the final concentration of the distillate. If we have 10 ml ethanol in 90 ml water, if we distil at exactly 78.37 deg C, the efficiency of evaporation for ethanol might be 100 % (meaning we are getting all 10 ml ehtanol) but the efficiency of evaporation for water might be ~40 % (meaning we are getting 40 % of 90 ml water = 36 ml water), giving us a final distillate of 21% ethanol. On the other hand, if we have 90 ml ethanol in 10 ml water, we are getting 100 % ethanol (90 ml) and 40 % water (4 ml) giving us a final distillate of 96%. The point of all of this is to illustrate that, distilling (or vaping) at the correct temperature still gives a distribution of all compounds in the base mixture.

How does this relate to vaping and flavour production? The boiling point of PG is 188.2 deg C and VG is 290 deg C. While boiling point is not the same as evaporation point, it will give us a good indication. The boiling point of the flavour components is unknown, since it depends on each mix and the flavour companies generally does not disclose this, and their chemistries change when steeped, but for the sake of argument lets say it is 250 deg C - somewhere between PG and VG. So what happens when we start vaping at a low wattage/temperature and slowly make our way up?
At low temperature, we are getting mostly PG. At slightly higher temperature, we are getting PG, some flavour, and a little VG. Even higher, and we are getting max PG, max flavour, and some VG. Finally, very high and we are getting max of everything. Now of course, max PG and VG in a 70:30 mix is 70% VG and 30 % PG. So even a little VG at lower temperatures might still be more than PG and flavour combined. Therefore, to get the most flavour concentration, we must work towards a very specific sweet spot (which will be different for each juice as well) - where the flavour evaporates at its maximum but with as little PG/VG evaporation as possible. (On the other hand, for cloud blowing we just want to go as high as possible, since we want as much VG to evaporate). When going higher than this sweet spot, we are getting the same number of flavour molecules, but at a lower concentration due to increased PG/VG evaporation - giving us less perceived flavour.

Lastly, unlike PG and VG, flavour molecules can undergo side-reactions at higher temperatures (usually denaturing into smaller chemical building blocks), which will reduce the perceived flavour. In the best case, it means you lose some complexity (as that wonderful strawberry and mint adduct breaks apart to give separate strawberry and mint perceptions); in the worst case, a flavour molecule denatures to the point where your senses cannot recognize it anymore.

All of the above points to the fact that mixologists very often give a perfect temperature for their mixes - anything below, and you're not vaporizing enough flavour molecules, and anything above you're reducing the final flavour concentration due to increased base liquid vaporization, flavour degradation or unwanted juice tones developing.


So... the actual temperature of your coil as it vapes is determined by many other things (see my previous wall of text, http://www.ecigssa.co.za/some-scien...ling-in-an-atomizer-evaluation-metric.t21258/). But given the same coil, wick and power in two different attys, the determining factor will be airflow. And more specifically, the velocity and amount of air on your coil directly (in other words, air pressure). In my previous post I talked about the equilibrium temperature - which is the temperature at which your coil is actually vaporizing ejuice, given the atty setup in terms of direct airflow on the coil. This equilibrium temperature must be at the flavour sweet spot to maximize flavour concentration. Anything higher or lower will reduce the overall flavour concentration. And unfortunately, temp control will create an artificial temperature - not the actual equilibrium temperature.

I hope this helps towards 'demystifying flavour production'. I know I haven't given any answers as to why smaller chamber attys give better flavour, or how coil positioning affects the science of it all... but I think you can rationalize mostly everything by thinking in the above terms (in terms of coil cooling and equilibrium temperature). If you're atty is currently vaping above the flavour sweet spot, you need to build in a way to reduce the temperature on the coil - in other words, more direct airflow on the coil, and vice versa if you're atty is below the flavour sweet spot. Finally, any change within the atty can be rationalized in this direction. For instance, increasing the wicking material (especially outside of the coil) can have big, usually negative, effects on the airflow. However, in the same vein, it can actually increase the air pressure on the coil even if it reduces the overall airflow, thereby increasing the cooling on the coil.

In terms of the smaller atty sizes: My personal guess (but it is only that) is that smaller chamber attys have, on average, the correct internal airflow for average builds in order to hit the flavour sweet spot. For instance, I've tried building crazier builds on my Goblin Mini, but I always go back to a more or less average build, as I've found that it always gives me better flavour. On the other hand, I've gotten great flavour from bigger attys - but I had to use more intricate builds. A triple-twisted single coil on a Smok TFV4 gives fantastic flavour, but is rubbish in the Goblin. On the other hand, two dual micro-coils on a Goblin is wonderful, but mostly just fog on a TFV4.

Final point, is that most attys can produce fantastic flavour, but you have to coax it from them. Smaller chamber attys tend to be easier to build for flavour.

Wall of text over... and I promise it will be my last one for a while! Takes too much time to read yo, which means very few people actually challenge some of the ridiculous statements I so often make!
@Ezekiel - Once again, super interesting and informative post. Thanks! Please don't take a break with these kind of posts. It doesn't make you sound douchey at all; perhaps (to rip off the grater accident guy) slightly never have I ever seen such really cool data-ey, but that's all cool
 
Even tho the Griffin is not one of the best flavor producing attys you need to build coils which can take high wattage on the griffin. I have only found decent flavor with claptons at around 80w+ on the griffin. But at 80w a kayfun doesn't come anywhere close as the high wattage brings out notes the kayfun doesn't.


Sent from my iPhone using Tapatalk
After a few days of use, I'm finding that in the Aromamizer Supreme, 2.5mm coils are just too small. The draw is too airy even on the smallest airflow setting - which hurts flavour. I then built a 3mm 7 Wrap Clapton build @0.45 ohms and its better... The highest I went was 60 watts because the resistance is a little high, which means the voltage per watt is also high-ish. What build are you using?
 
I have been using 26g 316L SS exclusively the last few months or so and last week I thought I'd pull out some clapton wire and get going.
Simple setup really dual coils 26g/32g Clapton 3mm ID 6 wraps .45ohm in my tank. At 65W this is the best vape I have had in a while. Seems I'd convinced myself that SS was a cleaner tasting, more flavourful vape when it wasn't. Over the weekend I did a small experiment and ran the same 6wrap 3mm builds @50W in the Velo, only difference was the wire. The SS build ramped up fast and I had tons of vapour - the clapton build was down on vapour but the flavour was much better. Although bump the clapton up from 50W to 65-70W and the vapour production matches the SS build.

Now I'm convinced the coil wire plays a much more important role in flavour than I'd previously thought. I think chasing clouds is easier than chasing flavour LOL
 
As a suitable metaphor, consider how distillation works. When we distil a base liquid (lets say malted + fermented barley, since that will give us whiskey and whiskey is awesome), we first heat the liquid to ~60 deg C, where methanol starts to evaporate, and keep it there for a while will the methanol boils out.
I absolutely DEMAND this analogy to pertain to Vodka instead. You lost me at 'whisky'... LOL jokes... Sheez incredible info mate. Absolutely incredible. A tip of the hat to thee.
 
Wall of text over... and I promise it will be my last one for a while! Takes too much time to read yo, which means very few people actually challenge some of the ridiculous statements I so often make!
Give me a minute to go talk to my engineer buddies and I will challenge away. Keep it coming this stuff is EPIC. Thanks for spending your free time on this.
 
A few two cents...

I agree with most of the comments above. I want to add a little bit of chemistry to the mix though. This is another technical discussion - its becoming a bad habit of mine, so after this one I'll try to chill it for a while as I'm starting to sound like a douche!

First of all, wicking. In terms of material, wicking can definitely change the taste. On the one hand, the wicking speed can have an influence on the amount of ejuice which can coat a coil at any instant - which will affect how much ejuice is vaporized. On the other hand, wicking material can form side reactions with ejuice components. Practically speaking, this will usually result in ejuice components being retained on the wick material instead of vaporizing. When your wick gets old, what I suspect is mostly happening is that more of the wick surface has reacted with ejuice components, which themselves can react with other ejuice components, giving a compounded result - usually, once a wick starts going bad, it gets even worse at a much faster pace. When a wick starts to singe, I'm guessing it starts to activate (open up binding sites) on some of the backbones (usually carbon) of the material - which will even further increase the reactivity of the wick.
Certain jucies - usually the darker ones, or ones with a significant sucrose content - reacts much faster with the wick, and again, this leads to decreased flavour much quicker, even when you use a more neutral juice afterwards.
Different materials will react with ejuice components a different paces. The effect can be very subtle - it might start reducing the flavour from the very beginning.
And of course, the actual taste of the wick can override certain flavours...
Interestingly, my hypothesis would be that wicks with higher silicon content will have longer longetivity... but I've only used organic cotton, so I have no real experience here.

The amount of wick have an effect on the internal airflow of the chamber, which I will address in a minute.

Next up is flavour perception. I think a bit of a common misconception that I've noticed is that flavour perception is based on the volume of flavour molecules present. This is indeed not the case - it is a factor of relative concentration. As long as the volume is large enough to sufficiently cover your tongue (and allow for evaporation throughout your entire olfactory system), the only difference in flavour perception will be a result of the concentration within your mouth. For instance, a big gulp of Coke won't taste more "Cokey" than a decent sized sip. The flavour concentration of the coke remains the same irrespective of the amount you drink.
In terms of vape, the flavour that you taste is relative to the other components - VG, PG and nic. If you build your atty in such a way that you vaporize PG and VG quicker than the flavour molecules, you'll get reduced flavour, and vice versa. Cloud chasers tends to maximize the tempo at which VG is vaporized, and when done correctly, will usually result in considerbly reduced flavour. On the other hand, it is possible to have a very flavourful vape even with very small clouds - which means that the flavour molecules is vaporized at a relatively faster rate than VG or PG, giving increased flavour concentration in your mouth, even though the total volume of the vape is quite small.

The question then is, how do the different factors of vaporizing ejuice affect the relative rates of ejuice vaporization? Heuristically, we know that a small chamber tends to give better flavour. Translating this into concentration and vaporization rates, it means a small chamber will usually vaporize flavour molecules at a relatively faster rate than the base liquid. To understand why, we must first discuss how heat affects different rates of evaporation.

As a suitable metaphor, consider how distillation works. When we distil a base liquid (lets say malted + fermented barley, since that will give us whiskey and whiskey is awesome), we first heat the liquid to ~60 deg C, where methanol starts to evaporate, and keep it there for a while will the methanol boils out. Next, we'll heat the liquid to ~78 deg C, where ethanol starts to evaporate, and keep it there for a while as we collect the ethanol. Finally, we selectively heat our base mixture (now devoid of methanol and ethanol) to higher temperatures in order to capture select flavour notes, which tends to have higher boiling points.
However, what would've happened if we skipped the first step, and heated directly at 78 deg C? At this temperature, the rate of evaporation for methanol will be the highest, followed by ethanol, whereas the rate of evaporation for any flavour compounds will be next to zero. If we collect the distillate at this temperature, we would get a high concentration of methanol and slightly lower concentration of ethanol, and no flavour. In the same line of thinking, if we heat directly to ~120 deg C, we would get pretty much the same concentrations in the distillate as what was in the base liquid.
Lastly, the relative concentration in the base liquid will also play a big role in determining the final concentration of the distillate. If we have 10 ml ethanol in 90 ml water, if we distil at exactly 78.37 deg C, the efficiency of evaporation for ethanol might be 100 % (meaning we are getting all 10 ml ehtanol) but the efficiency of evaporation for water might be ~40 % (meaning we are getting 40 % of 90 ml water = 36 ml water), giving us a final distillate of 21% ethanol. On the other hand, if we have 90 ml ethanol in 10 ml water, we are getting 100 % ethanol (90 ml) and 40 % water (4 ml) giving us a final distillate of 96%. The point of all of this is to illustrate that, distilling (or vaping) at the correct temperature still gives a distribution of all compounds in the base mixture.

How does this relate to vaping and flavour production? The boiling point of PG is 188.2 deg C and VG is 290 deg C. While boiling point is not the same as evaporation point, it will give us a good indication. The boiling point of the flavour components is unknown, since it depends on each mix and the flavour companies generally does not disclose this, and their chemistries change when steeped, but for the sake of argument lets say it is 250 deg C - somewhere between PG and VG. So what happens when we start vaping at a low wattage/temperature and slowly make our way up?
At low temperature, we are getting mostly PG. At slightly higher temperature, we are getting PG, some flavour, and a little VG. Even higher, and we are getting max PG, max flavour, and some VG. Finally, very high and we are getting max of everything. Now of course, max PG and VG in a 70:30 mix is 70% VG and 30 % PG. So even a little VG at lower temperatures might still be more than PG and flavour combined. Therefore, to get the most flavour concentration, we must work towards a very specific sweet spot (which will be different for each juice as well) - where the flavour evaporates at its maximum but with as little PG/VG evaporation as possible. (On the other hand, for cloud blowing we just want to go as high as possible, since we want as much VG to evaporate). When going higher than this sweet spot, we are getting the same number of flavour molecules, but at a lower concentration due to increased PG/VG evaporation - giving us less perceived flavour.

Lastly, unlike PG and VG, flavour molecules can undergo side-reactions at higher temperatures (usually denaturing into smaller chemical building blocks), which will reduce the perceived flavour. In the best case, it means you lose some complexity (as that wonderful strawberry and mint adduct breaks apart to give separate strawberry and mint perceptions); in the worst case, a flavour molecule denatures to the point where your senses cannot recognize it anymore.

All of the above points to the fact that mixologists very often give a perfect temperature for their mixes - anything below, and you're not vaporizing enough flavour molecules, and anything above you're reducing the final flavour concentration due to increased base liquid vaporization, flavour degradation or unwanted juice tones developing.


So... the actual temperature of your coil as it vapes is determined by many other things (see my previous wall of text, http://www.ecigssa.co.za/some-scien...ling-in-an-atomizer-evaluation-metric.t21258/). But given the same coil, wick and power in two different attys, the determining factor will be airflow. And more specifically, the velocity and amount of air on your coil directly (in other words, air pressure). In my previous post I talked about the equilibrium temperature - which is the temperature at which your coil is actually vaporizing ejuice, given the atty setup in terms of direct airflow on the coil. This equilibrium temperature must be at the flavour sweet spot to maximize flavour concentration. Anything higher or lower will reduce the overall flavour concentration. And unfortunately, temp control will create an artificial temperature - not the actual equilibrium temperature.

I hope this helps towards 'demystifying flavour production'. I know I haven't given any answers as to why smaller chamber attys give better flavour, or how coil positioning affects the science of it all... but I think you can rationalize mostly everything by thinking in the above terms (in terms of coil cooling and equilibrium temperature). If you're atty is currently vaping above the flavour sweet spot, you need to build in a way to reduce the temperature on the coil - in other words, more direct airflow on the coil, and vice versa if you're atty is below the flavour sweet spot. Finally, any change within the atty can be rationalized in this direction. For instance, increasing the wicking material (especially outside of the coil) can have big, usually negative, effects on the airflow. However, in the same vein, it can actually increase the air pressure on the coil even if it reduces the overall airflow, thereby increasing the cooling on the coil.

In terms of the smaller atty sizes: My personal guess (but it is only that) is that smaller chamber attys have, on average, the correct internal airflow for average builds in order to hit the flavour sweet spot. For instance, I've tried building crazier builds on my Goblin Mini, but I always go back to a more or less average build, as I've found that it always gives me better flavour. On the other hand, I've gotten great flavour from bigger attys - but I had to use more intricate builds. A triple-twisted single coil on a Smok TFV4 gives fantastic flavour, but is rubbish in the Goblin. On the other hand, two dual micro-coils on a Goblin is wonderful, but mostly just fog on a TFV4.

Final point, is that most attys can produce fantastic flavour, but you have to coax it from them. Smaller chamber attys tend to be easier to build for flavour.

Wall of text over... and I promise it will be my last one for a while! Takes too much time to read yo, which means very few people actually challenge some of the ridiculous statements I so often make!

I have not read this post before. I started this thread and my last post was before this post, it was a turbulent time for me so I didn't follow up, at the time. I see he hasn't been on the forum since 2018, sadly. :(

Epic post. And apparently not the only epic post he made. I will spend some time digesting some of what this gent had to say. Re this thread, he has made me think a little deeper about the subject.

I tip my hat.
 
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