Looking for a more in-depth discussion here.

You can largely divide the current batch of pour over vessels into open vs flat - so that's debate #1.

Debate #2, in each style there are competitors:

Open:
V60
Origami
KONO
Chemex*
etc.

Flat:
Kalita Wave
Stagg X/XF
etc.

Assuming 'perfect' methodology exactly how minute are the differences going to be from one brewing apparatus to another? I don't have, say, a refractometer to test (I think I need one though, in general)... but to me I can taste *slight* differences between a V60 vs a Wave vs a Clever dripper, but I can't really tell the difference between a V60 and a Origami with the same beans.

*Chemex is kind of an outlier because the paper is so thick it's almost a third category IMO, but felt to include it anyway.

Me again. Lots of great info on this here. Check these out for starters!:

"Best" Flat Bottom Dripper Showdown
Which dripper do you chose to brew with?

Like everything else, there is theory and there is practice. I would actually separate the drippers into conical shape or flat bottom. In theory, flat bottom brewers would give you a more even extraction. Conical drippers can allow water to bypass at certain points. The conical dripper may allow coffee to fully bypass (meaning it completely runs down the side of the wall, between the filter and the coffee) or partially bypass by flowing through coffee at the top of the bed and then down the sides. Also because the bed depth is higher down the middle, areas like the bottom middle of the coffee bed is harder to extract.

Flat drippers should be less susceptible to these issues, however, the holes at the bottom of the stagg and the kalita are prone to getting clogged when the filter gets wet and sinks into them and, because they have pleated filters, you have the issue of coffee getting stuck in the folds as well as water bypassing between the folds and the walls of the dripper. That's why some people will use v60 filters or fold the creases of the pleated filter to create a smooth filter.

I have a V60, Switch, Origami, Kalita, Tricolate and a Stagg and favorite combination is the Stagg X with cafec v60 filters (which I turn inside out and push down and against the sides) with a dispersion screen on the bottom of the brewer under the filter to prevent the filter from clogging the holes. I just made a brew with this that was 23% extraction and was delicious. The Stagg also is insulated so it retains heat better than a lot of brewers, which is nice.

That said, I'm sure other people have had other experience with conicals. This is just my experience.

Ejquin wrote:Like everything else, there is theory and there is practice. I would actually separate the drippers into conical shape or flat bottom. In theory, flat bottom brewers would give you a more even extraction. Conical drippers can allow water to bypass at certain points. The conical dripper may allow coffee to fully bypass (meaning it completely runs down the side of the wall, between the filter and the coffee) or partially bypass by flowing through coffee at the top of the bed and then down the sides. Also because the bed depth is higher down the middle, areas like the bottom middle of the coffee bed is harder to extract.

.

If I don't swirl my v60 towards the end and I just let the water run out...... There is a layer of coffee coating all the walls....... There is no bypassing down walls. To get that coffee to sink to a nice even bed I do a little swirl or two as it's draining down.

As you say there's theory, and there's reality.
In reality is the only thing that counts.
And what counts there is taste. Only taste.
Everything else is just fools flapping their lips. Mostly trying to sell people more gimmicks. Or their devices. Or making their living by promoting their methods, or YouTube videos, etc.

If coffee tastes good, drink it.
If it doesn't, change something.. until it does.
There is no perfect cup there is no ideal cup there is no perfect extraction....... Only fools to sell devices to. If you're running a coffee shop, then extraction is $$.

Yeah...ok. I don't think that just because there's a layer of coffee coating your filter there is no bypass. Anyhow, personally, I've brewed many v60 brews but prefer flat bottom by taste with the adjustments i mentioned.

Brien wrote:Looking for a more in-depth discussion here.

You can largely divide the current batch of pour over vessels into open vs flat - so that's debate #1.

Debate #2, in each style there are competitors:

Open:
V60
Origami
KONO
Chemex*
etc.

Flat:
Kalita Wave
Stagg X/XF
etc.

Assuming 'perfect' methodology exactly how minute are the differences going to be from one brewing apparatus to another? I don't have, say, a refractometer to test (I think I need one though, in general)... but to me I can taste *slight* differences between a V60 vs a Wave vs a Clever dripper, but I can't really tell the difference between a V60 and a Origami with the same beans.

*Chemex is kind of an outlier because the paper is so thick it's almost a third category IMO, but felt to include it anyway.

I've been using my origami as a flat. I've cut a plastic mesh to the same star shape pattern to rest where the bottom of a flat bottom filter would rest. I've enjoyed the results.

pure cone shape brewing is prone to dry spots. if you don't bloom well and agitate water doesn't make it to the bottom. This can be tested by simply doing a bloom without agitation but the problem is not just the bloom it shows what the flow of water is also during the brew. what actually happens in a pour-over brewer is the paper filter is lifted off the walls of the brewer (most of them) from it's ridges on the walls (designed for just that). This is the dominant design in most pour-over systems. The Origami accomplishes this by its star pattern preventing the filter to seal against the walls where the hario has little ridges, each brewer has it's own method but each accomplishes the same thing.

When you watch the drawdown of these brewers you can watch the slight bubbles/foam on top travel from the center and migrating to the sides. it's not as noticeable in the center but at the edges of any surface "foam" it will slightly be pulled into the sides of the walls. this is showing the flow of the water which is not going straight down, but rather being drawn to the slides where it escapes through these gaps between the walls and the filter; this is called bypass. from my visual observation, my theory is this is far greater than we give it credit and in the entire coffee bed water is not travelling up and down but moving downwards but drawn towards the side.

flatbottom's cut off the bottom and this dry zone that cones are predisposed is reduced or removed. there still is bypass (if the filter is still lifted from the walls) but the flow is better at reaching the bottom of the coffee bed. I made a quick diagram and it is greatly exaggerated to show what I'm talking about (there's a super large gap between brewer and paper) but it just demonstrates the idea. This is a theory too and the pictures don't make it any more official, so just keep that in mind.



I have made a 3" PVC pipe brewer where the bottom had a cap with many holes in it (like an oversized Aeropress. I then put a mesh on this cap and lab-grade circular paper filters and put the cap on which seals the paper in place (again similar to an Aeropress). the drawdown is very slow but I observed an opposite phenomenon than from the pour-overs that the water was drawn not to the sides but away from the sides towards the center. this is because there was no paper filter along the walls and so there was no paper lifted off the walls and no bypass. the water's flow was bypass-free and only went through the cap at the bottom. so the water's flow was pulled by the strongest force, in this case, the bottom but for the cones that force is along the walls where the bypass is happening.

this is a theory of course and I don't have the ability or know-how to go into strict testing so although I can obverse what's happening and get consistent results as well as apply a theory, it still is somewhat anecdotal. a refractometer would help somewhat but I don't claim to be an expert in fluid dynamics and if anyone is, please comment on this.

Andrew; Since we're hypothesizing on fluid dynamics through brewers, I have one to add for the V60 :

The ridges in the cone of the V60 that hold the filter away from the cone surface are more pronounced at the bottom than the top. My theory is this might have been done to mitigate the issue of bypass and to increase overall flow through the coffee bed.

When the cone of water is sitting on the coffee bed early in a pour, it exerts pressure to the walls of the V60, pushing the filter against it and likely also staunching the bypass flow.
Gagne's recent research seems too suggest that when a filter is pressed against a brewer's surface that flow isn't great through it.

Meanwhile, the ridges are more pronounced at the bottom of the V60, which lifts the filter from sides, increasing filter surface area, and thus promoting flow there. So, my theory on bypass for the V60 is the ridge design promotes flow through the coffee bed and not around it.

Obviously this is challenging to prove conclusively. One could also say that bypass increases toward the bottom if water leaks directly from the water cone on top to the sides versus flowing through the coffee and then out the sides of the filter.

Yes I think your right. If a faster flow can be promoted closer to the bottom this means more water will be directed to the bottom. It's like looking at a large multilane freeway. The faster a lane goes the more cars are going to go through. Also to add to my earlier post the PVC brewer I made that is bypass free directed water to the center away from the walls because of the no slip barrier which says at the walls there is no flow and at the center the most flow is happening so it has an opposite effect than bypass where water will move inward not outward.

I believe the KONA brewers (which have been around since the 70s) only have the ridges at the bottom half. Now I don't know what R&D they put into this in the 70s but I suspect they had a smooth cone and the draw down was too slow, so they added ridges and it corrected the drawdown so they left it as it was. Hario has made the ridges a part of their design and I suspect more R&D into it. They have a new brewer called the V60 single extractor with what appears to me a more soft approach to the ridges in large diamond like shapes with a star like pattern at the bottom.

The chemex was made in the 40s and it has no ridges just a giant hole. But the unusual folding method of the paper creates a double layer on one side which I think acts similar to ridges. It's interesting to look at the history, chemex to Kona to Hario. As it progresses more ridges are added.

Japanese brew pour over very different than the west which I think is important to understand as they are quite influential in the pour over space. Hario, Kona, Kalita, origami are all Japanese based. The west looks at styles like Rao, Hoffmann and Perger all designed to be easy, repeatable and cafe friendly. The east however values the process as much as the product and view things like pour over as more process rich and skilled (just look at Tetsu Kasuya 4:6 method right on harios channel) if you can't repeat the results it just means you haven't mastered the skill and you need to keep practicing which is a very different mindset than the west.

It is more common to not bloom (and if you do not to agitate), multi pours, and center pours. This treats the coffee like an immersion brewer somewhat as all the coffee immediately floats on top and the center pour continues to keep the coffee on the top with a thick crust just like an immersion. The bloom keeps the coffee at the bottom where if you don't bloom a thick crust floats on top. I used to reject that method but I am approaching it differently now and am trying a hybridized method. I used to say it's drilling a hole in the middle and makes a giant channel, but that's not what it's doing, but rather positioning the water under the coffee bed which clogs the paper filter less. My hybrid version is playing with finer grinds that take advantage of the coffee floating to not clog the filter but breaking the crust early enough to actually percolate water through it.

As to how it impacts the cup, I'm still playing with it.

Ejquin wrote:Flat drippers should be less susceptible to these issues, however, the holes at the bottom of the stagg and the kalita are prone to getting clogged when the filter gets wet and sinks into them and, because they have pleated filters, you have the issue of coffee getting stuck in the folds as well as water bypassing between the folds and the walls of the dripper. That's why some people will use v60 filters or fold the creases of the pleated filter to create a smooth filter.

folding in the pleated filters can help lessen the effects of bypass but at the flat bottoms, you actually want the paper lifted away from the brewer. this is why people add mesh because the mesh lifts the paper off of the bottom promoting the flow where you want it. I've run experiments with an Aeropress (which is bypass-free) and a mesh plus paper filter in the bottom of one and only a paper filter in the other. I only added water to them (no coffee), the same about for each and poured it in from a cup as fast as I could. This was exclusively to test the effectiveness of a mesh and the one with the mesh had a faster drawdown than the one without the mesh without any other restrictions.

without the mesh even if the brewer has some sort of ridges at the bottom it will seal in some places which will slow the drawdown. The amount of holes usually doesn't matter and as long as you have raised the filter off of the bottom the flow potential will be greater than what's coming through the coffee bed. I made two 3" PVC brewers one with a cap like the Aeropress with a bunch of holes and the other with no cap at all and it just had a mesh glued on the bottom so essentially unrestricted flow. Both had a paper filter over top of a mesh. you would think the second one would have a faster drawdown but in the end, it didn't affect the drawdown speed because the coffee bed had the slower flow. I think with most brewers people keep thinking more holes the better which probably doesn't do anything at all but a mesh at the bottom does wonders.

if you have a mesh and can promote faster flow through the bottom you promote better flow through the entire coffee bed as now water is directed to where you want it to be. I think for manufacturers a good and simple solution for the bottoms of the filter would be a perforated bottom with many holes so that the perforated rough edge sticks out in the inside like a cheese grater. the raised rough edge will lift the paper and if you have a pile of them it will promote good flow.

I use a plastic mesh sheeting that has worked very well. I compared it with a tea strainer mesh and it has the same performance except the plastic one can be purchased in large roles, super cheap and very easy to cut shapes out of plus it doesn't fall apart.

I use this which happens to fit perfectly at the bottom of a stagg x: https://flairespresso.com/product/pro-d ... on-screen/