Corvus Log

The case for Flat Bottom Brewers

by Doug Stone |


Flat Bottomed Brews, You Make the Coffee World Go Round!

“Batch brewers are just so inconsistent.” -No Barista Ever

Single cup manual brews are sexy, but you just can’t deny the consistency of larger batches of coffee. With increased batch size comes an increased margin for error. Put it this way: If you’re ten grams over or under for a 200 gram dose, you’ll detect way less of a difference than if you were ten grams off of a 20 gram dose. The same thing is true of other factors; a few seconds longer brew time for a V60 makes a big difference when the whole brew lasts two and a half minutes compared an eight minute gallon-sized brew.

But what about the middle ground? I’m thinking of manual brews at home for several friends. There are only few practical options. For one, you can make one giant French press, of which I am a fan. But not everyone likes to chew their coffee. Alternatively, you could make an aeropress or a V60 for everyone. Have fun grinding coffee and pouring water for the next twenty minutes while everyone else enjoys breakfast!

Then, there are a few pour-over companies who have made it possible to do bigger doses all at once, the main one that comes to mind being Chemex. But the problem I have with the Chemex is that the cone comes to a real point and if you don’t have a quality grinder it can flow at a very slow rate. The water stops dripping and leaves you scratching your head thinking you’ve defied gravity somehow. Think about it—how many big batch brewers have you seen with a traffic cone-sized filter basket? No, they all have flat bottoms. And don’t get clogged. And taste the same every time.

I recently got my hands on a Stagg [XF] pour-over brewer by Fellow. It has tall straight sides that form a cylinder and the filter looks just like a skinny version of a big basket filter. I love designs like this—the Kalita Wave is another one—for all the same reasons why nobody stresses out about brewing coffee on big batch brewers. A 24-ounce batch of coffee would take ten minutes or more to finish brewing on a Chemex (I would know, I’ve done it a time or two) while on the Stagg, it completed in about four and a half minutes. It’s so handy that I’m thinking of incorporating this style in our own brew bar service here at the roastery. 

And because the brew bed is flatter, there’s less technique required for the bloom and throughout the pouring process, even with single-dose brews. The flat-bottoms of the pour-over world are user friendly, consistent, and can make enough coffee for your brunch guests without tying you up for a half hour at the kettle. Count me in!

A quick note on Ethiopia

by Phil Goodlaxson |

With our newest Ethiopian from Kayon Mountain in I wanted to drop a note about my experiences in Ethiopia. A lot of our favorite coffees come from Ethiopia, and I would say that is true for 90% of coffee roasters. They're exotic and unique, unlike any other coffees in the world. Generally speaking, quality coffee is synonymous with really knowledgeable farmers and advanced agronomy and processing techniques. Visiting Ethiopia really shocked this idea, and drove home the importance of soil. 


Coffee evolved in Ethiopia, and all coffee comes from strains in this region. Visiting farms here I was really surprised to see how much of the flavors I've come to love in Ethiopian coffee are a result mainly of this ideal climate ad soil. Many of the farms had very little knowledge of agronomy practices compared to Latin American farmers. They weren't pruning trees systematically, planting mainly government approved varieties, and doing little nutrition management. But their coffee was fantastic! The buyer from Sweden who I was traveling with made the comment that if we would take a Colombian coffee farmer and give them soil like this, the results could be incredible!


So, the potential in Ethiopia is still enormous. Farmers are starting to hire agronomists, keep better track of coffee as it moves from the field through processing (micro-lot work), and understand the importance and benefits of practices like pruning and spacing trees appropriately. Ethiopians as a general rule are an unusually friendly group of people, good natured and open hearted. The coffee is fantastic already. Working with farmers like Ismal at Kayon Mountain and seeing him adapting more micro-lot practices; tracing coffee in individual plots picked on specific days through the entire process gets me excited about how much better the coffee here can get!


The Flash

by Doug Stone |


The warm weather is upon us and with it iced coffee season! It’s no secret that we love cold brew here at Corvus; we have five different kinds in bottles alone not including the many Kyoto cold brews you can try at our DTC location. But those all take hours to make, and if I’m outside by the pool craving iced coffee, I don’t always want to wait until sundown to drink it! In that case, I’ll use a method we refer to simply as “flash brew” in which we use hot water to brew coffee directly onto ice. It makes a really sweet cup of iced coffee in mere minutes rather than waiting hours for immersion-style cold brew.


I enjoy using the chemex for this for a couple of reasons. For one, it’s big enough to hold a few cups so I don’t have to keep brewing non-stop, and it’s also its own decanter which is pretty handy, too.

Here’s where I get hung up when it comes to recipe creation for flash brew. When making hot coffee, the cup is entirely made up of water that passes through the bed of grounds. In the case of flash brew, some of the the water is from melted ice that was not used to brew the coffee. But it still affects the final strength which, by the way, is constantly changing as the ice melts. I’m a bit of a numbers nerd with my recipes, so this melting ice concept had me chasing my tail.

I was using our Boloya from Ethiopia which is always delicious, so how hard could it be? I tried several things: Increasing the ground coffee dose by 50%, 100%, coarse grind, fine grind, I even tried brewing the coffee at a super strong concentration and adding the ice afterward. Nothing seemed to be working, and that was when I learned my lesson. I was over-thinking it. So, I finally tried something simple: Take half of the brew water away and replace it with ice in the decanter. Using half of the normal amount of water to brew coffee would make me expect an under-extracted sour tasting cup that is too strong. But what resulted was sweet, bright, and balanced. 

I always say this in the coffee classes I teach: The numbers don’t mean anything if it doesn’t taste good. And just when you think you know a thing, coffee will humble you. I guess that’s just the magic of it all.


Here’s the exact recipe I used:

21 grams of Ethiopia Boloya ground medium

160 grams ice in the bottom of the chemex

176 grams of boiling water to brew


If you don’t have a chemex, use my trainer code “flashbrew" for 10% off online or in store!

limited to 20 customers

Espresso in Milk

by Doug Stone |

I've recently heard baristas suggest pulling espresso shots a bit shorter for milk drinks than for straight espressos. The idea put forth is the shorter shots will have a stronger flavor to stand up in milk versus a more balanced and "weaker" longer pull of espresso. The problem is with lower yield comes less extraction. This means you lose significant sweetness and the espresso becomes more acidic which will not be best for a cappuccino.
Let me give an example. Let’s say you’ve got our new Boloya from Ethiopia dialed in to an 18 gram dose with a 45 gram yield in 27 seconds and it tastes great. The acidity is balanced pleasant peach and floral notes. Now you want to make a cappuccino with a shorter shot so you aim for a tighter ratio at around 30 grams out. If you don’t also adjust the grind you will have to cut the shot off quicker by as much as 8 or 10 seconds. This will give you an ultra light-bodied acidic espresso. Rather than having fruit flavors it could taste generically tart like under ripe peach.
Additionally, the longer recipe gives you more coffee to mix with the milk.
In summary, we generally advise a longer shot recipe for an espresso to go into a milk drink. But as always with any suggestion I make—coffee brewing or otherwise—experiment, taste, and decide for yourself!
Curious about this and want to improve your barista skills? Attend one of my milk or espresso classes!

Changing Things up for Santa Inez

by Doug Stone |

If you’ve ever taken my brewing class you’d already know that “The one thing we never change is our desired extraction!” After all, you’re always aiming for the same brew strength in your cup and the same percent of solids extracted from your coffee grounds. Until you’re not. Let me explain.


Think of this half wheel of flavor notes as representing all of the different flavors you can get out of a coffee. Notice how the upper section of lighter colors is the lighter more acidic flavors (floral, fruity, etc). The middle section which is caramel-colored is where all the flavors of sugars browning are found—those caramel, chocolate, classic coffee backbone flavors. And lastly, the bottom section of darker colors is where the darker flavors live, and these flavors aren’t all that great. The tend to overpower the others and make a cup of coffee taste bitter.


What’s really cool about coffee brewing is that these flavors aren’t all extracted uniformly from start to finish. Rather, they are dissolved in order of how they are arranged in a clockwise fashion. First, the lighter acidic compounds come out, then the more complex caramelized flavors, and lastly the heaviest bitter ones. This works to our advantage because we can brew through all the flavors we do want from about 12 o’clock to 4 o’clock on the wheel (fruity-floral-chocolate-caramel) and leave behind the rest of the stuff we don’t want (ashy- medicinal-burnt).

If you’re a pro and can consistently achieve even extraction, then you want to maximize the amount of positive flavors, like all the way through to 4 o’clock on the wheel. That’s why our recipe at Corvus for cups of coffee is 18 grams of ground coffee for 336 grams of water used to brew. However. Sometimes, that sweet spot of “all the flavors you want and none that you don’t” is in a markedly different spot on that metaphorical flavor clock.

As it turns out, one of the new coffees in our lineup gets kind of funky a little “earlier” on in that half wheel than most. To put it another way, the section with purple colors starts a little after 3 o’clock instead of right at 4. Imagine that “Turpeny” flavor note sitting on the wheel where “Syrup-like” currently lives. This doesn’t mean the coffee is somehow flawed. It’s not. It’s name is Santa Inez and it’s one of the most delicious coffees I’ve tried in a while. 

For this coffee we want the same strength of the final brewed cup but I've found that a  slightly lower percent of extraction(again, a little before 4 o’clock on the wheel) tends to taste much more lively. If you want to extract less flavor from the coffee grounds while ending up with the same strength of brew, one easy adjustment is to start with more coffee. That’s why I increased the dose of ground coffee from 18 grams to 21 (or went from an almost 1:19 ratio to 1:16). This took the brewed cup from fairly good to unbelievable. Like, stunningly good. If you’ve got your method down for brewing and have a firm grasp on the relationship of strength and extraction, see what adjusting your ratio can do for a coffee! The industry recommended extraction is based on the general preference of a large study of people's taste opinions. While this is still fairly reliable, it can be good to remember that end result in the cup is what determines if the numbers make sense, not the other way around.