Corvus Log

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. 

I Now Pronounce You Coffee and Brewer Part 2

by Corvus Order Fulfillment |


In this follow-up post I will go over the recipe and complete brewing technique I used for both cups tasted for comparison in the last blog entry. Note: If you haven’t already, go read that first!


The recipe for both Chemex and Hario V60:

Dose: 18.0 grams of ground coffee

Grind: 4.25(V60) and 4.5(Chemex) on our EK-43

Total Water: 336 grams(mL)

Bloom: 45 grams water and quickly stir*, then wait 30 seconds

The rest: 3 more slow pulses of about 100g water, reheating to boil between each pulse and pouring the last drop of the 336g at the 1 minute 35 second mark.


*I omitted the stirring step for the Chemex


I’m a proponent of stirring right after the bloom(very first pour of water). This ensures that all the coffee grounds start brewing at the same time and for the same amount of time throughout the brew as opposed to waiting for the slow drip of the water to make its way through the coffee bed, losing temperature and extracting energy. 


Something can happen though when you stir the bloom: The smallest dusty bits of the ground coffee or “fines” can migrate down to the bottom of the brew bed. In the case of the Chemex the brew bed is a cone made of a super thick piece of paper which is also folded to be three times as thick on one side of the cone. This fine migration is enough to clog the Chemex filter and slow down the drip of water so much that it takes over ten minutes for a brew to complete (if you can even get all the water to drip out, that is). You might expect the resulting cup to be over-extracted and too strong, but in fact the opposite happens. The water hanging out in the cone for ten minutes cools down so much that it no longer has the energy to dissolve more coffee on its way through it.


Here’s my workaround: Use a spoon to spread out the bed of ground coffee up the sides of the cone as thin as possible so the water doesn’t have as far to travel to soak all the way through. Start in the center of the bed with your pour and spiral outward and upward for the bloom. You’ll know you did this properly if you don’t see any big bubbles coming up from the bed while you pour the rest of your brew water. 


Once the thick filter was accounted for with enough pre-wetting and the technique described above, the resulting cup of coffee was equally as flavorful and clear as the cup from the V60. The V60, however, finishes dripping about two minutes faster. That’s why you’ll see us using Hario V60 drip cones instead of the Chemex in Corvus.

Doug Stone
Director of Training
Corvus Coffee Roasters

I Now Pronounce You Coffee and Brewer

by Corvus Order Fulfillment |

I get this question from customers a lot when they’re in our shop picking out a coffee to take home: Which one works best for ______?(insert your favorite home-brew method) I thought I’d take a minute to lay out my philosophy of coffee brewing to try and answer that question.


In short, every type of brew method should be just a slightly different means to achieve the same end. If I had an amazing cup of a particular coffee that was brewed on a Kalita Wave, I should be able to turn around and make the exact same cup on a Hario V60. There are a few obvious differences in brew methods, the biggest one in my opinion being the type of filter used (or lack thereof). But most differences are rather subtle and can be easily accounted for in a couple simple techniques.


I also get the feeling that a general lack of good technique has given rise to the notion that the different brew methods produce drastically different cups of the same particular coffee. Example: Regarding the Chemex brewer, I often hear something of the effect that it produces a “sweeter” or “less acidic” or you-name-it type of cup, and the reason given is “because of the filter”. This has never made sense to me conceptually, so the other day I set out to brew two side-by-side cups of the same coffee, one on a Chemex and the other on a Hario V60.


The similarities: Both methods are cone-shaped, use paper filters, and have large openings for the brew to drip.

The differences: The chemex is its own decanter, and its paper filter is WAY thicker than the V60. Why does that matter? Some of the most nuanced and unique flavors in great coffee are the first to brew out, and the Chemex filter acts like a giant sponge sucking up those flavors keeping them out of the cup. 

The solution: Pre-wet the Chemex filter. Like a lot. Soak it. Then soak it some more. Just don’t forget to dump out that water before you start brewing! This is is the first bit of technique to keep in mind. It also matters with the V60 filter, but not nearly as much.


I used the most recent roast of our Las Lajas Red Honey from Costa Rica as the coffee for this experiment. I brewed using the exact same recipe and pouring technique for both methods with one very small difference, but I’ll talk about the actual brewing for the experiment in a follow-up post. For now, I’m going to skip to the results.


After a few test brews, I got both methods dialed-in to produce the exact same cup strength—to within a hundredth of a percent—and extraction percentage, which I checked with a VST refractometer. So, on paper the same cup of coffee. But how did they taste? I took them both to our roaster and resident Q-Grader, Jeremy to taste with me. The consensus between the two of us was that there was no discernible difference in the resulting cups. Clarity? Check. Taste notes? The same. Body and Mouthfeel? Surprisingly the same. 


All of that to make this point: Any coffee, if it’s a great coffee, should be amazing on any brew method you have available. And if someone makes a claim about something—coffee brew methods or otherwise—make an effort to see for yourself! You just might be surprised at what you find.

Doug Stone
Director of Training
Corvus Coffee Roasters