6 Bar vs 9 Bar: The Impact on Espresso

[@LanceHedrick]

MUST READ: First, I've been reached out to by a university that has done this same test and have arrived at the same data. This will be published soon(ish) Some supplemental information for those not wanting to look at the data! There was no statistically significant difference between shot times or extraction yields between 6 and 9 bar. For tasting, other than the odd Alaka, the results were random. Qararo- I chose 6 bar thrice and 9 bar twice, Rui chose 6 bar twice and 9 bar thrice. Leona Tabi- We both chose the same cups identically- three 6 bar shots and two 9 bar shots. Alaka- We both chose 9 bar for each one, but I suspect this is separate from pressure threshold. Please leave a like and comment if you enjoyed! Or, if new to the channel, a subscribe would be awesome! Cheers and looking forward to chatting below!

[@kylemessineo8542]

Hey Lance on my Breville barista touch is there anyway to troubleshoot or hack into bars of pressure & manipulate them to play around with different bars?

[@nichj487]

Hi Lance! I’m interested in this idea that a 9bar shot might be preferable if it leads to increased flow earlier in the shot. This is super interesting, as a lot of Decent users doing flow profiling are actually trying to do the opposite - have the machine decline pressure so the flow doesn’t shoot up as the puck loses integrity. This is pretty fascinating, no?

[@abdullahalsufyani9705]

❤

[@mikni4069]

@@nichj487The 9 bar shot isn’t holding 9bar at puck throughout the shot, it drop as he say as the puck integrity cannot sustain the sort of pressure with that specific coffee, so with that a drop seem to be preferable. There is a difference between input pressure at pump and pressure at puck.

[@nichj487]

@@mikni4069 Yes I understand this. But Lance commented that they preferred the shots where the machine’s pump pressure was set to 9bar, and he speculated that it was because the flow sped up earlier in the shot than it did when the pump was set to 6bar. And yes, the 6bar shot had a different grind size, which explains the difference in flow. But I’m curious to know why he thinks that earlier spike in flow might be better.

[@mosraelthewaker]

Prediction: eventually, Lance will determine the ideal espresso is pour over

[@LanceHedrick]

.......true.

[@parasbhargava6047]

pourpresso!

[@T0M3R07]

Honestly, I laughed at this one. Does it mean that I'm officially a coffee nerd?

[@lovesonification]

@@T0M3R07 If it makes you happy…… Yes 😊

[@MrGlenardan]

​@@T0M3R07 You are watching a 15min video on whether you should pull 6 or 9 bar espresso shot, you are a coffee nerd 😅

[@exonusgod]

Lance asking the questions that have real value for both home and professional coffee consumers. Thank you. Honestly I'm very happy you make videos and I found them.

[@LanceHedrick]

Thank you! Appreciate this comment.

[@exonusgod]

@@LanceHedrick appreciate your videos! If you'd be interested I think it would be cool to explore direct pump machines vs those with preinfusion (if you've not done something already that I've missed). I think there could be some interesting data on extraction and cup quality which might be helpful for people trying to figure out if the extra cost for the feature would be worth the investment for their daily routine. It's one of the few topics people talk about alot but there isn't much coverage with real data, it's just assumed preinfusion is much better (from what I've been able to find).

[@TylerH266]

The Burr Man? Nooo…the Bar Man. Thanks for raising the Bar, Lance. I know creating this content can be a lot of Pressure. When it comes to the coffee community, I nominate you as the Group Head. 😬

[@LanceHedrick]

So many good puns here. I'm sure I'll be eviscerated in some fora but I gotta present what I spend hours gathering haha! Appreciate the support

[@TylerH266]

@@LanceHedrick All jokes aside, we appreciate everything you do. The most influential provocateurs are the ones who challenge traditional beliefs. Keep grinding my dude

[@alanmajors9100]

The pressures, the continuous grind, all to be roasted by others in search of their own leverage. Lance, please keep pumping out the content. Or was that cold brew truth?

[@alanmajors9100]

Surely more puns will percolate up?

[@TH-tl8hy]

Keep chasing the dopamine, Lance. Keep pushing against assumptions and pressing into the data. You're a big encouragement to us all!

[@Kindred1a1]

Data-driven coffee content is what every coffee channel should do. Thank you Lance

[@ShinSuperSaiyajin]

Lance dropping… bars. Ok, I’ll see myself out.

[@JohnSmith-zy1ur]

🥁

[@slickfast]

Lance as an engineer and research scientist it’s fantastic to see your use of the scientific process to brewing better espresso. You have tremendous resources relative to most home baristas, so I really look to your testing to shed some light on what all these factors do! What’s crazy is that many people, including people around me in my community, get tripped up by their own biases and critical thinking to discern what can be objectively relevant data. Thank you for acknowledging what is tested data and understanding the limitations of what has been proven vs what is speculation

[@LanceHedrick]

I super appreciate this comment! Thank you so much!

[@vsepotap]

This is 100% true. So much mystical thinking in coffee.

[@johnl7374]

“Vomitable” great word of the day.

[@LanceHedrick]

It's in my daily vernacular

[@JimmyNewCakes]

​@@LanceHedrick This just in: Lance finds coffee vomitable.

[@mattscarf]

Almost as good as ‘cuspice’ 😄

[@andrewreida6514]

Vindication! Last few weeks I've basically stopped worrying about pressure as a variable. As long as I'm hitting my ratios and times the pressure naturally trends to around 7-9bar anyway, and the results have been great. This hobby is fun.

[@richardbennington6289]

Wow! Just wow! In many things, true scientific tests involving taste are near impossible without a ton of tasters, a ton of controlled variables, and a lot of statistics. You guys did an amazing job without breaking the bank, complete with insight into the subject matter that a scientific study may have missed.

[@vaghatz]

For once, a video saying that it's OK no need to change anything, what a relief!

[@TomsIRL]

Really raising the bar with these videos

[@whitelotus_zero]

😂😂 you won sir ☝️

[@ScottyMcCraigles]

As you mentioned Lance, I believe it's more flow rate that determines the best cup in terms of flavour. While anecdotal, I have been pulling 15, 13, 11, and 9 bar espressos on my pressure modded breville infuser for the last year and have noticed that the taste is best when the flow is a finer stream. Since the flow increases as the puck deteriorates, adjusting the pressure to maintain a finer stream appears to produce a better tasting cup. I do 21.5g in to ~50g out, preinfusion at 3-4 bars for 6 seconds (including ramp up time) and anywhere from a 34-54 second pull depending on the colour and flow rate. If the liquid is quite light or clear, I end the pull by dialing down the pressure to 3 bars over 2 seconds.

[@zroeder]

This is pretty much my approach with a lever machine. Whenever the grind isn't quite right, it always seems ideal to adjust pressure to achieve the proper flow rate.

[@elitebicycleracers]

Lance, I'm glad you made this video. One of the first things I did when I got my Micra was drop the blind-basket pressure down to about 7 bars, based on suggestions and anecdotes I had read. Been at 7 bars ever since. Today, after maybe a couple thousand shots later, I decided to raise it back to 9 bars. Lo and behold, the shot looked and tasted better. The crema was richer, darker looking (a medium-roast Colombian from Kuma). The flavor seemed noticeably better, sweeter. Maybe it's all in my head but I am looking forward to more experimentation.

[@dparad22]

This was exactly the testing I was hoping to find a few months ago. Thank you for all your hard work, Lance!

[@LeonardoCavanha]

That's why I love direct levers - I don't really know what pressure I'm pulling, the effort I have to make depends entirely on grind size, puck preparation and resistance during the shot and not the other way around. Great video!

[@gregorio5543]

The more you chase flow rates and pressure seems to bring everyone to a lever. It’s perfection. I eventually want to get a spring lever

[@vsepotap]

I thought nobody will ever do this research. Thank you so much, Lance!

[@emeraldrose512]

I did a barista course, only an intro course, but it truly opened my eyes to how good coffee is and how much it matters about your coffee, your barista, the steaming of the milk.....I never knew this!

[@relyt_png]

Lance consistently dropping knowledge and relieving head aches haha. I can stop worrying about pressure now and remove one more variable to stress over.

[@Gibrilswings]

never thought i would out a coffee youtuber on Hoffman's level, but in recent times i have found myself going to your channel over his.. many thanks for all the info and gems... and ofc music.

[@jumarina555]

Thank you !! I have learned a lot from all your videos. I also believe that flow rate of the puck is the most importance.

[@odinallfather8241]

FTR, when I started trying to figure espresso out, I found Lance and James early on. I've found many others now. Some very helpful. But still, it's Lance and James the produce content that continues to excite me.

[@Horico12]

do you have recommendations outside of them? I havent found anyone I enjoy as much as them

[@odinallfather8241]

@@Horico12 coffeeKev Tom’s coffee corner and Morgan eckroff. Spellings might be wrong but you should be able to find them. James and lance are still the pinnacle, but the other three have been invaluable in my coffee journey.

[@Bf3GentlemanXY]

I am just here to say i love these kinds of videos, keep it up!

[@seansteele792]

As a data scientist myself, I love these data based coffee videos and I love seeing P-vals in espresso!

[@Kiaulen]

Well, since my Apex has a 15 bar pump and no OPV, most of my shots start about 11-12 bar and go down from there. But I've definitely had the grind a bit too coarse a few times and started closer to 8 and averaged about 6. Tasty coffee basically every time. I appreciate all the work you do here. Also that white decent with the hummingbird looks absolutely phenomenal. Can't wait for my hummingbird to come in.

[@matz4k]

love your approach to coffee, this feels like a breath of fresh air compared to most ppl in this hobby. Just had an happy accident today while trying a new coffee. Got it too course the first time, pulled 40 out of a 15g shot in 14 seconds or so, looked awful with the open basket. But bc broke college student I won't waste coffee, tried it and it was actually quiet nice.

[@lawrenceliu8787]

Excellent video! This perspective is quite similar to my usual approach, which is to focus on the flow rate rather than pressure. Since my espresso machine doesn't have a constant pressure function, I don't need to be too concerned about maintaining a strict 9-bar shot. Instead, I usually pull something more similar to a turbo shot with a flow rate of 2-3 g/s at 4-6 bar. The rate at which soluble substances dissolve is theoretically correlated with temperature, concentration gradient, and surface area. Therefore, I guess the key is to ensure the coffee grounds are ground to an optimal size - not too coarse, so that the inner substances can be effectively extracted by the water, and not too fine, so that the grounds can be extracted evenly. For a perfect extraction, the flow rate should remain steady, but it may speed up slightly as the puck resistance decreases. The flow rate determines the concentration of the water used to extract the lower grounds. Considering that the lower grounds are actually extracted by the coffee itself rather than just the water, a faster flow rate may be useful to achieve a more even extraction yield between the top and bottom of the puck. So I tend to use coarser grind settings compared to my friends. Even though this may result in a slightly less intense shot, the clarity and consistency of the extraction is often better.

[@Mastrenich]

Great video Lance, I want to add that I'm pretty sure keeping the duration of most of the videos under 20 minutes will eventually help to get more views. Finding interesting 12-16 min. videos in the feed is synonym of CLICK 😜

[@ggcadc]

Interesting experiment. I love the results. I think is hilarious that we're looking for empirical evidence in something so subjective as taste. We want to validate being "correct" in our preference, so human.

[@HauntedSheppard]

Taste itself is not that subjective, especially when trained. Enjoyment thereof is.

[@thomascee]

FANTASTIC! Been SUPER wondering the answer to this question!

[@suppersday]

Well produced video, going into the weeds of espresso. Love it.

[@tecknoize]

Great video as always! I'm starting to believe that flow rate is one of the most important independent variables. It's also much easier to visualize dialling variables (grind size, puck volume, etc) in relation to their impact on flow rate.

[@Gk2003m]

Almost anyone with a machine with a vibratory pump can get control over their flow rate. A simple lamp dimmer (the kind you find inside a torchiere lamp; these dimmers can be purchased for $12 or less online) can be added to your machine on the ‘hot’ side of the pump wiring. Allows preinfusion; makes a world of difference in controlling your extraction.

[@odinallfather8241]

TBH, this is something I've been very curious about. Thanks for the data as always!

[@DamirZrno]

Strietmann in the back. Yeaaaaaa. Gimme that review please !

[@MaltePersike]

Fully agree. I created a "preinfuse - bloom - 6-to-4.5bar decline" shot profile for my girlfriend. Just accidentally used that profile on an Ethiopia bean ground for 9 bars. Best shot I've ever had for that coffee.

[@ersatemek9052]

Finally the MAX SSW is on the show!!

[@pitstopcoffeeco]

I think it's crucial to bring milk into this study. Over the years my favorite espresso shots that were pulled were all tasting incredibly sour in even just the slightest amount of milk. If I ground finer and pulled longer, the beautiful delicate notes I loved about that espresso were nearly gone completely in the black espresso. The only way I could pull an espresso shot with intense delicate notes that both never folded under milk and tasted incredible as a black espresso was lowering the bar pressure from my typical 7.5-8 bars I've been using for years across hundreds of coffees and pulling longer shot times (faster shot times like I had been using make light espresso in milk not taste sour, but they lack flavor character especially in milk with vst baskets and specifically my workflow, this could be unique). The lower I go, the more intense and delicate flavors remain. I go about as low of a bar pressure as possible before the espresso tastes sour in milk, then I'll go up about .5-1 bar higher just to be safe. This is how I dial in. Granted, I'm using vst baskets and pulling shots for over 1 minute often with about 12 seconds of pre infusion on my mavam. I'm also using hopper fed beans or full dose feeding with wanted retention in my grinder above the clump crusher. If I slow fed In my bentwood I would not be able to grind fine enough for my beans to run through the burrs. This is highly specific, but this has worked wonders for me. I also know a lot of other shops using the mythos and hopper fed (commercial) grinders where they've found that lowering the bar pressure pulls incredible shots for both black and white drinks. Many of which had been shocked by the change. I should say that with these modern baskets, I can pull shots that blend well with milk and show origin character even at just 12 seconds pre infusion and literally as fast as about 8 seconds of 4-5 bar pressure with my ssp brew burrs 😂 I think the modern baskets are much more of a different story with white espresso. Though I do prefer traditional baskets with longer shot times for both black and white drinks if I'm being critical on flavor, but it's MUCH easier to avoid using these techniques and just pull fast shots with modern baskets at one grind size for nearly all coffees. I'll take that small flavor sacrifice any day for a high volume bar. Just thought I'd share my experience with milk based espresso in regards to your video. Thank you for taking the time to do this test! I'm glad more people will know that bar pressure for black espresso doesn't matter as much. Maybe we can see this topic of white espresso discussed soon? 🤩

[@AM2PMReviews]

Good point. My espresso is usually a little flat white or 60-75ish grams of milk to 43 grams of liquid espresso. It seems I dial my shots in just for the addition of milk at this point 😂

[@softbeak8333]

Great analysis. I would be interested to validate your results by comparing 6 va 9 bars for each coffee by comparing effects on different grind settings, rather than holding that as a constant. Because then the flow rate should be varying and it would be interesting to see how that compares from coffee to coffee with 6 vs 9 bars.

[@texarkana3781]

I settled on 8 BAR adjusted OPV in my Gaggia Classic. Good middle ground and works very well indeed. Much better than OEM stock (~12.5 BAR)

[@JimNortonsAlcoholism]

This is why I love my Micra with very little customizability. Just solid shots, one after the other.

[@propertwb]

Remarkable work, Lance.

[@QuinCarter]

Again, breaking the internet! Another great video, Lance!

[@elementonyoutube6556]

Soooo Awsome! You two just made history. I don't know much about light coffee, people always say they're more difficult to extract but overextraction ruins taste. Is it possible a 2:1 ratio on lighter roasts is too much? You didn't have to drop in a set of nconsistent coffee beans, but you did and that's even more awesome. Your sacrifice for science is Well appreciated ❤

[@PlanckRelic]

Watch Lance's previous video about dialing in espresso.

[@elementonyoutube6556]

@@PlanckRelic umm, ok

[@PlanckRelic]

@@elementonyoutube6556 Not being snarky, if you understand what he's teaching in that video, I think you'll answer your own question or at least have a more nuanced formulation. 2:1 is not too long for a light roast, but Lance will teach you better than my typing.

[@elementonyoutube6556]

@@PlanckRelic Its a good video, and I don't mind a refresher. But his comment about the lighter 6bar roast being bitter makes me think it could have been avoided meaning this experiment on this video has just been ruined because the extraction on the 6bar was not optimized in accordance to his last video. Its possible. He mentiones this at about 14:20ish minutes and delves into further as he reaches 18+min.

[@PlanckRelic]

@@elementonyoutube6556 check his pinned post, it was only 1 of the light roasts that showed any consistent difference. This experiment also does not argue that you couldn't adjust other things to avoid the defects of one particular situation, he's intentionally only changing one variable. He also argues this experiment does not arrive at a universal conclusion, which seems to be the thing you are trying to make from it.

[@alexwilson27]

This makes me feel like I’m not missing out on anything by not adjusting my OPV to 6 bar, and that’s great because I really didn’t want to mess around with that!

[@spirqc]

Awesome day ahead with a new video

[@lIlIlIllIlIlIlIIl]

Awesome shirt man, also: is there a review on the Kafatek coming? Loving the videos!

[@sunflowerdeath]

Why to choose between 6 and 9 bars? Just use both - go up to 9 very briefly, then go to 6, gives best results for me 😅

[@quantitativecafe]

I'm really loving this recent run of experiments. If I undertand correctly, the biggest difference observed here (with the Alaka) was perhaps due to a greater change in flow rate during the shot, correlated with a change in pump pressure. Intuitively, it feels like changes in flow rate during the shot would affect the representation, e.g., of early vs. late extraction products in the cup, which would presumably affect the balance of the shot. As a "first order" extension on this, it's not clear to me how a flat flow profile (let's call this a "neutral" representation of extraction products) would compare with, say, a flow rate that increases or decreases as the shot progresses (presumably favouring either early or late extractin products). Do you have a sense of how simple changes in flow rate like this would affect the shot?

[@HuibNederhof]

With the Nurri lever espresso machine, I get much better and higher extraction with very light coffee when I do a blooming shot with a pre-infusion of 6 bar then with 3 bar. The pre-infusion takes also longer time with 6 bar, 40 seconds and 25 s for the 3 bar pre-infusion. When the cup gets 1,5 gram of coffee (the pressure is down to 3 bar), I let go the lever for a 10 bar shot. Total shot time 60 - 80 seconds My theory is that this is due to the rapid increase in pressure that the machine can provide with a large amount of water.

[@ted_maul]

Purely anecdote and not data of course but having owned a Decent for 18 months after playing around, I settled on dynamic flow-controlled profiles which always seem to give me the most consistent, pleasant results. It's almost impossible to make a sink shot with them.

[@tigerag29607]

I've been waiting for this one ❤

[@AM2PMReviews]

What about flat 9 bar vs, a nice smooth pressure drop from 9 to 5ish?

[@andrewwatkins5613]

Good info thanks Lance!

[@andrewjung2919]

oh why thank you so much. American James Hoffman 😂 I needed this test.

[@devongreer9233]

Under pressure 🎶

[@DenkoYugo]

Man, some breakneck speed on your releases lately

[@raahulpathak]

He must already have all his videos planned for the year.

[@LanceHedrick]

haha I wish! all completely random. just what i'm vibing with.

[@raahulpathak]

@@LanceHedrick, well you’re posting so many videos so fast that you sure look like you have all your videos planned for the year. Either that, or you just have the process from conception to publishing down to a science so you’re able to do it faster.

[@vitriolicAmaranth]

Okay, but what is the pressure threshold beyond which this lack of distinction appears? Obviously there is one- At 1 bar you have pourover and that is obviously not espresso, whether or not you prefer it to espresso. At 6-9 bar you have similar output for most use-cases (maybe, but I think it's compelling that different people report opposite results comparing the two, suggesting that while individual tests that lack adequate data to form well-founded conclusions tend to lean one way or the other, the collated data from everyone suggests that other factors probably influence the perceived difference). So somewhere between 1 bar and 6 bar is a point above which you can't make a clear distinction with most grinds of most roasts of most beans when controlling for factors like ratio and oxidation (until you reach a second higher threshold that common knowledge says is around 10-12 bar), and below which one would presume there is a characteristic gradient from pourover to espresso.

[@GadgetsGearCoffee]

You skimmed by it but the quakers in natural coffees is interesting. It would explain why from shot to shot it can be inconsistent at times for my coffee, often naturals.

[@tummy_fritters]

I come for the coffee info, I stay for the media literacy

[@jslanfranchi]

Very instructive, but it’s kind of your signature. Flow to puck degradation having more of an impact on final result than pressure does make a lot of sense. Out of personal experience this may be the reason why my manual shots (Robot and Flair 58) may be a step above my e61 ones, even though I rarely pay too much attention to gauge and tend to rely on puck feedback. Also, thanks for getting me to discover a French roaster that was not on my radar. Will try them for my next order.

[@Somelucky]

For me it's all about getting in an appropriate pre-soak with perfect pressure profile for that precision flow rate. Just observing how changes to those profiles impact the extraction indicate how important flow rate really is.

[@jg3142]

I’m confused about the shot times. As I understand it, the grind setting was the same for both 6 and 9 bar shots. According to the theoretical model from the paper “Systematically Improving Espresso: Insights from Mathematical Modeling and Experiment,” I think we should expect the flow through the puck to be faster at higher pressure, when grind is held constant. A more minor point, I think we should also expect EY to be higher for longer shot times, if yield is constant.

[@LanceHedrick]

Yes the model is simply wrong. I spoke with hendon about it.

[@jg3142]

@@LanceHedrickah! I did find one error in the model formulas, but that issue wouldn’t change these predictions. I still have hope for the overall approach because it has the potential to give a unified theoretical understanding across brewing methods. In theory, we’re exposing the solubles in ground beans to hot water as a solvent for a period of time, so there’s a continuous space of brew methods and no sharp boundary between them. In practice, though, the different details matter a lot! Did you find fixable errors in the formulas, assumptions, method or was it the predictions don’t match live shots? I’m just wondering how fixable their model is.

[@jahdgreat]

Waiting for this finally!!!!!

[@potkettle]

Gonna set up a 9-bar ExDos profile on the Decent for tasting tomorrow morning. I pretty much only drink naturals, so we'll see how it goes. Also just correcting my subscription status to the channel. Thought I was, because I see everything you put out, but take my plus 1. I also used to live in Bordeaux, nice to see they've got a decent coffee scene sprung up.

[@LanceHedrick]

With exdos, which is a fast shot, there is likely a difference. The results here mostly are in relation to more static style shots.

[@emadventures6975]

Thoughts on 8 Bars? Just to slightly lower the pressure and have easier pulls

[@eddywijaya474]

Very inspiring... Its teach me alot

[@brentroman]

Thanks again for the video. I think it will be very interesting in 30 years when we look back at this time in coffee history. How much more will we learn. I feel like everything we “learn something new”, we learn there is so much more we do t understand. Coffee is hard.

[@LanceHedrick]

Oh for sure. I'm confident a lot of these tests will be complemented in the future with much better understanding and rationale. But, we can't get there without questioning first! And putting a spotlight on the issue first. So, we push thru!

[@brentroman]

@@LanceHedrick “push thru…vomitable dark roasts”…. Hehe

[@SeanGordon-ym4yf]

I would love to hear your thoughts on 11 vs 9 bar, and the potential impact on channeling, as so many machines come set well above 10 bar. Anecdotally, when I dropped my machine from 10.5 to 8, my consistency improved. I fully acknowledge that this could be confirmation bias.

[@plektosgaming]

One thing that a slightly lower setting will accomplish for those semi-pro/not quite commercial grade machines is a much longer service life. So if you have a method at a lower bar that works great, by all means don't put extra stress on the machine if you don't get better results by doing so. :)

[@joker927]

This video is above my level. I hear 9 better but not much, do whatever.

[@michaelevan9184]

The flavor profile change may be due to the different grind size and not the pressure.

[@marcoandremartins]

Nice test 👌 Question: since the last coffee the shots were so fast were you hitting 9 bar? On my machine shots around 20/22s do not go past to 7bar

[@asok15146]

Another great video from Lance, thanks! As a Flair user, I wonder how this impacts the direct lever machines. It is easy to realize with the Flair that trying to keep up the pressure (by applying more and more force on the lever) throughout the extraction is a bad idea, and will result in very harsh tasting espresso and mess all around. So a declining pressure profile is definitely the way to go. But do you want to keep the force on the lever constant? Or the flow rate, after the coffee actually starts flowing? Or none of these and ease up even more (or less) towards the end? These are exciting and meaningful questions.

[@obiwanbill5506]

I’m also a Flair user (18 months). I focus on length of time per shot (I aim for 30s). I ramp up to 9 bars, sometimes more or less depending on grind size, then lower the pressure to achieve a 30s pull. Obviously I use grind size and dose amount to “dial in” that 30s pull, but I’m not always dialled in, so the Flair manual lever makes it easy to adjust. Frankly, my dose size is 10g, with 25g output using a ridge less 15g VST basket. We only buy green seeds, so we roast and I’ve been collecting data on which seeds we like the most. Then I blend and experiment to determine what blend we like!

[@nimitzg]

With the 0.6 mm giclure I guess the water debit is more reasonable than the 0.8. I lowered the pressure to get 250gr/per second as the machine arrived stock with nearly 490gr/sec. Shots improved dramatically in taste.

[@SaberFTW]

I've been doing 6 bar shots for 6 months now and i found my shots were much more consistent, less channeling and spraying and has been alot easier on the flair 58.

[@LanceHedrick]

That's great! Anecdotal, but do what you find best for you!

[@thejohnz0r]

i feel like these findings suggest that my cafelat robot is really one of the best machines that allows you to adjust the pressure based on resistance and flow rate 'on the fly' which leads to less wasted shots... as you can still get decent shots even if your grind size is off by simply adjusting the amount of foce applied to the lever arms

[@MrEye4get]

I must set the grinder on my Buono all-in-one expresso machine to the finest setting to get the pressure in the expresso range. If I go just one click larger, the pressure won't reach the expresso zone. I've almost dialed in the recommended recipe, but the result is unimpressive. Another issue is when I fill the basket with 16g of coffee, the puck touches the extraction screen. I can barely fit 15g of coffee in the 58mm cup.

[@MCCole]

Thanks for sharing another awesome experiment. Did I understand you to say flow could have more impact than pressure?

[@achimbarghorn714]

badabum badabang! thanks lance & keep it up ✌️

[@JakubTarnawski]

Now let's say that my puck prep is not very good, or my grinder is not great - then could I hope to avoid some channeling with 6 bar? Also, you mentioned naturals being less consistent shot-to-shot than washed coffee - was that comment about Ethiopian naturals, or in general?

[@LanceHedrick]

I don't think 6 Bar will salvage anything. It's still crazy high pressure. And naturals in general, tho Ethiopia is quite bad.

[@petercaddy]

Thanks Lance

[@ericmed]

Does Onyx in Bentonville pressure profile?

[@Jaroslav.]

Hi Lance, wouldn't it make sense to get a multi group machine for your tests? I'm sure you thought of it already, but just asking in case you didn't 😄

[@LanceHedrick]

Issue is multi group machines aren't perfect. I've never found one where the flow rate from each group was identical.

[@Jaroslav.]

I see! That makes sense.

[@The_Ubatron]

Thanks, Lance... So, if the taste and extraction are indiscernible between six and nine bar, would we consider using a lower pressure to lessen the strain on the machine components, thereby prolonging the life of the machine? 🤔

[@cirrusmcgoat6272]

1) Am I understanding correctly that you think the 9 bar tasted better because of the increased flow around the end when the puck gave out? I tested this at home with a washed light roast from Peru (from Elm in Seattle, which was pretty good) and had the same experience: the 6 bar was "grittier" and harsher than the 9 bar, but I wonder if this is because 9 bar is extracting less overall (thinking of that volcano graph in the turbo shot paper) and therefore just has less flavor (not necessarily bad) 2) I have seen that Flat Max in the background a few times now and now you're using it for your experiments. Is a review forthcoming? Big thanks for your work, as usual

[@LanceHedrick]

9 bar was ONLY better on the washed Ethiopia. Completely random with other two.

[@Flygnisse]

Great vid! Thanks!!

[@crawdaddyy]

A possible way to test ‘fines migration’ would be to use small metal or wood shavings (or any identifiable small substance) and note their starting point in the basket and where they end up at the end. It’s not perfect but it would give an idea of what’s happening

[@TomJones-tx7pb]

I have noticed that the extraction characteristics of fairly freshly roasted coffees changes over time, stabilizing somewhat over time. I presume this is due to the amount of CO2 blooming being produced, and the CO2, being a gas, is influenced in size by the pressure in the puck. When the coffee is fresh, I have had better luck at preserving puck integrity at 9 bar over 6 bar. After a couple of weeks aging, if I get puck saturation quickly at 6 bar, I no longer see such large differences in behavior or taste.

[@johnl7374]

Why are we showing the decent doing the shots, I thought it was linea mini r? Do you think that the relatively high dose could be a factor, ie maybe an 18g 6 bar might be better than 20g 9 bar? Thanks for the video, very interesting as I drop my pressure on light roasts to 6 because that’s what we are supposed to do.

[@LanceHedrick]

I used the decent in the video because I considered showing graphs but ultimately decided not to for the sake of simplicity since I was already showing other data. The experiment was done on the linea.

[@wretchedpkmn]

You know there's a band called Vomitorial Corpulence who's music I think would describe the experience you had with your second shot of commercial.

[@_zeketorres]

Interesting, thanks for sharing! What about testing 1 bar and 3 bar shots??

[@ShadowKylar]

I wonder if we should be discussing water velocity as well. You touched on this slightly when talking about the differing flow rates between grinds and setups. Velocity is the 3rd factor when considering standard flow hydraulics, if you have 2 pipes, 1 is 20mm diameter and 1 is 40mm, both have 50 litres per minute @ 5 bar flowing through them, whats different? the velocity. the water must move faster in the 20mm diameter pipe. If a course and finer ground coffee both had 2 ml per second @ 9 bar flowing through them, surely logic indicates the finer grind would have to have higher water velocity occurring? Higher velocity is more turbulent and exerts more friction, perhaps it could also be disturbing a puck more, carrying more fines with it and altering texture accordingly.. All just speculation from an amateur coffee enjoyer and ex irrigation system designer haha. What do you think?

[@Majnun74]

Is there any logic in holding the cup directly under grouphead to capture the espresso stream at a closer distance? Apparently the diving gravity affects consistency?

[@pauldistasio4385]

What is that black portafilter used around 6 mins?

[@Laurent1us]

A little OT: How do you change the pressure in Linea Mini R; just on the flow when pulling a shot or do you use a blind basket always? -A happy owner of Linea Mini R

[@BrianKimCreative]

As a someone with a Bio degree, I appreciate the effort to set up the experiment

[@jsuwangsa]

Maybe the best way to pull espresso is the friend we made along the way.

[@LanceHedrick]

This is the way

[@ishantsingh3366]

You open youtube for some video, then see a Lance hedrick video, then you forget about why you came to KZbin and spend the next 15-30min listening to Lance 🤷🏻‍♂️

[@LanceHedrick]

Haha! Shorter one today so only 15min. Or put it at 2x speed and crush it sub 8 min! Lol

[@ishantsingh3366]

@@LanceHedrick not that I was complaining

[@rampant59]

Lance, the rabbit hole has become deep. I predict in the not-too-distant future you walking away from coffee and going into another field of research having exhausted everything there is to know about coffee brewing tasting extracting etc. In a not so parallel universe the headlines read Lance Hedrick loses his mind when he wakes up from a dream and finds out that everything he's researched about coffee has been a simulation and that coffee doesn't even exist.

[@dabougi8063]

"The pressure is not important, the flow is" Well, if course. It is like voltage and current. Problem is, to control current you need to control voltage and resistance. So flow is always output, not input. Exception, of course: true flow (current) control. But then, you have to adjust resistance and/or pressure/voltage. But I do not really get the point here...