(bright music) - Welcome to the Understanding Espresso series, a series where we take apart on individual variable in the espresso making process. In the past, we've looked at dose in, ratio and brew time. Today, we're looking at the most complex of the variables in my opinion, which is the grind setting. how fine or how coarse you should be grinding the coffee, and when you should use your grind setting to make an adjustment to taste. Espresso is a lot of fun, but it's also immensely frustrating, especially when you're starting out. And I would say, this variable is by far the most frustrating of all of them to work with. And I'll give you the reasons why. And there's kind of three reasons. So let's say you make a grind setting change going a little bit finer. In doing so, you'll expose a lot more surface area of the ground coffee. If you think about cutting an apple into big pieces, there's not that much surface area, but if you diced it down into tiny pieces, you'd expose a lot more of the inside of an apple, and the same is true with a coffee bean. And so far, that's good news. More surface area is very useful for extracting more coffee flavor. But when you change the surface area, you also change the way that the grounds interconnect with each other. And when you tamp them down in your little pack of coffee, the finer the pieces are, the better they fit together, and the harder it is for the water to flow through them. This will increase the contact time between the water and the coffee. So you have this one change to surface area that impacts flow rate and contact time as well, and that's a bit of a headache. And then for an extra twist, quite often, changing the grind setting is a little bit wasteful. Now, this isn't true of every single grinder ever made but it's very true of many, many, many coffee grinders people use for espresso. They don't perfectly push out all of the coffee that they grind every time that you use them inside the grinding chamber that houses the burrs as well as the exit chute, you'll often find some residual ground coffee and that was ground at a setting maybe before you made a change. So when you make a change, you need to purge out some coffee, to push out to these old grounds that are sort of set at the wrong ground setting with some new ones. And that's frustrating because some grinders need a lot of purging and others don't. But either way, that's coffee that you never get to drink. That's coffee that you waste. And so, changing the grind setting is frustrating, but it's necessary. Without grinding finely enough, you can't do the extraction work that you need to, to get all the good flavor out using only a little bit of water. And that's the kind of nature of espresso because you want to use just a little bit of water to have a strong, concentrated, thick, delicious, gooey, sweet espresso at the end of it. Now just quickly, I wanna go back just through how we got to this point, a little bit of history. People worked out pretty early on that to brew faster you had to grind finer, that way this increased surface area meant that those flavors were more accessible. But quickly you get to the point where there was a problem. Finely ground coffee is difficult to get water through. And in the early years of espresso, different methods were found to increase the pressure that the water was pushed through with the coffee. Eventually, with compressed springs, we got to the kind of pressures that we use today, around nine bars of pressure. It's equivalent in strange money of 130 psi, but ultimately, it's nine atmospheres of pressure. And that is a lot of pressure. That causes problems in espresso brewing. Generally speaking, you wanna go as fine as you can expose as much surface area as you can, before you break the puck. Espresso brewing happens at these very fine pressures and they are dependent on resistance coming from the coffee cake. But at some point, that very high pressured water may well find a channel through which to run, an easier pathway. And what happens when an espresso puck essentially breaks is that it begins to channel and more water begins to flow through less of the coffee. Channeling happens in most expressos at some point and to varying degrees. But as you go finer and finer and finer, you increase the likelihood of the channel forming because you created such a lot of resistance to the water pressure. Now the grind is not the only variable that dictates how good a job your puck does of creating even resistance throughout the whole brew. Obviously, the depth of the puck will play a role, as does your puck preparation and how evenly the coffee is distributed before you tamp it down. Often people will talk about over extraction when you grind a little bit too fine. I know I've done that too, and we associate that word with very bitter flavors coming through in your espresso. Generally speaking, the puck as a whole may not actually be over extracted. The puck as a whole maybe under extracted actually. But the areas around the channels where water has flowed much faster and in higher volumes, they are extremely over extracted. So they've given up more flavor than we want, and they've added that bitter harshness to the shots, but you'd argue that's really more uneven extraction than it is over extraction. Or just localized over extraction rather than total over extraction. Because again, if you're measuring this stuff with refractometers, and looking at your total yields, you won't see a big increase in extraction, that incredibly fine grained, you'll actually see a drop. And in the past, this actually pushed people to experiment with a much coarser grind than is typically used for espresso, in a paper that was published, and I made a video about that, so you should check that video out, up here, when you're done watching this one. Now, I'm not gonna say you have to use very coarse grains, because you end up needing to use a higher ratio to get a more balanced shot. But you do get a more even extraction using these slightly coarser grounds than you do using rare finely ground coffee, but your end result does feel and taste and have kind of different texture and strength to it. So let's talk about using grind on much more practical way. I would definitely use grind to first and foremost, get my flow rate about right. Let's say I'm looking for an 18 grams in 36 grams out in around 30 seconds. Well, I'm gonna use my grind setting to get me to that point. But once I'm there, I'm gonna taste it and chances are, the tweaks I'm gonna make, if the espresso is good, but not perfect, are gonna be two other variables that we'll discuss. If I'm still a long way, away from good tasting, I say I'm still very sour, I'm gonna go finer again, and see how that does, even if it's outside of my original spec. But if I get my grind setting approximately correct, then I'm gonna make those little tweaks with dose, with yield, potentially with temperature in some cases but unlikely, but primarily, I would suspect with my coffee in and my coffee out. They're gonna let me fine tune that recipe, pretty easily. Now the reason I like to use grind like this for the big changes, but maybe not as often when I'm tweaking is actually largely practical. If you're a beginner or intermediate in the world of espresso, then I think making less grind changes is probably an easier thing. There's waste from purging, there's just the general frustration around making those changes and making them accurately, especially if you have a new grinder or you're just new to the process. So I think big changes with the grind are good. And also if you have a stepped grinder where the steps between each setting are quite large, then again, I would go probably for the finer of the two, even if that means dropping down my dose and that kind of stuff. 'cause I'm just more likely to have a good experience that way than being stuck with a slightly coarser grind that I might want. If I lived in a world with unlimited coffee, unlimited time and resources, then I would use grind to really, really, really make small adjustments. But that needs a very good grinder, a lot of patience and quite a lot of waste. And I'm not sure that's great real word sort of advice or recommendations. So I would say, you're more likely to enjoy your espressos and the espresso making process if you're not throwing away a ton of coffee each time. So at the risk of repeating myself, use your grind to get close, get good tasting espresso. If things are dominantly sour, you need to grind a little bit finer. If you're finding things are getting a little bit too bitter and harsh, or you're getting a lot of channeling, then maybe come back a little bit coarser. I'll summarize all this in a second. I'll give you some basic rules for using grind. But first, I wanna talk about the sponsor of this video, which is Skillshare. Skillshare is an online learning community full of thousands of classes for creative and curious people like you and me. And if you watch these videos, then you'll know that over the years Skillshare has been very useful for me to develop my filmmaking skills. But there's a lot more than just filmmaking classes there. Recently, I've been enjoying a Productivity Masterclass from Ali Abdaal. Now, I'm very curious to listen to someone who manages to be both a full time Youtuber and a doctor at the same time, because it lines up with my values, which is you can't just work more hours, you've got to work smarter. And his approach is really interesting. It's a great course full of tons of useful information. And there's so much more inside Skillshare to feed your curiosity. And for less than $10 a month, with an annual subscription, you get unlimited access to every class and I think that is fantastic value. So if you're curious, if you're one of the first thousand of my subscribers to click the link in the description down below, and sign up, and you can get a free trial of Skillshare premium. Thanks to Skillshare for sponsoring this video. So to wrap up, I'll give you a few simple rules to use when thinking about grind setting. So rule one, once again, use it to get in the ballpark of tasty. Fix your recipe, don't vary that, just use your grind setting to get to pretty good and then tweak from there using your other variables in the recipe. Rule two. Generally speaking, push it as fun as you can before you start to see channeling happening. Now channeling will be very obvious if you're using a naked portafilter and you'll start to see uneven flow in your basket especially in the last third of the espresso, but you can also see it in the spotted portafilter, you'll just be looking for a sudden increase in flow rate as coffee starts to gush out of their spouts in the last third of the of the chart or potentially the last half if things have gone really wrong. Channelled espressos tend to taste a little bit weaker than you expect, kind of hollow. They have this acidity coupled with this bitterness that you get in the finish, this kind of harsh biting aftertaste. In the past I've even recommended grinding from some grinders into a little collection chamber or bucket or tin or something, shaking out any potential clumps and then dosing into your portafilter from there, for this kind of a reason. Puck prep is really important, but going to fine will produce channeling, kind of no matter what. Rule three. Only change one flow related variable at a time. If you're changing your grind, do not change the dose of coffee in your bucket the same time. You won't understand or get insight into the impact of either one that way, and you won't know what's gone right or what's gone wrong. So if you're changing your grind, keep everything else the same, so you can understand the nature of the change that you've made. And rule four, purging is essential. And it's better to purge and waste five grams of coffee than it is to waste the whole dose that you ground incorrectly, pull the shot off and waste it. So if you are changing a grind setting, with most grinders, five grams, 10 grams, it really depends on the make and the model, but just make sure, you're getting nothing but the new grind setting that you wanna test, to see if it makes the espresso that you want to drink. But now I'd like to hear from you. How do you feel about setting the grind? Does it freak you out? Does it stress you out to change your grand setting? Does it feel like you make a change and nothing happens and then something happens later on or you just feel like you chase it around and around and around and around and you never get where you wanna go? And I'd love to hear from you, down in the comments below. Let me know which bit of this spoke to you, let me know what you want me to go into, in further depth, in the future. But for now, I'll say thank you so much for watching, and I hope you have a great day.