Coffee Ad Astra
1.32K subscribers
105 photos
11 videos
44 links
Coffee brewing tips for the geekiest
Download Telegram
I just released a post on my public blog ! In this post, I go further in the comparison of espresso shots pulled with the Niche Zero versus the EG-1 with SSP ultra-low-fines burrs. Measuring the difference in output coffee weight versus input water weight yielded estimated total dissolved solids that are consistent with the changes in viscosity that were predicted in my last blog post !

This is yet more evidence for a completely different interpretation of why espresso shots almost always become faster during a shot. We often hear that "the puck falls apart", "channels form", "the puck erodes", but I am now becoming convinced that it is the decreasing coffee viscosity that drives this change most of the time, as the coffee becomes less concentrated. Concentrated coffee is more viscous, and viscous fluid is harder to push through a porous medium (the coffee puck) ! Maybe some shots fall apart, but even shots that don't fall apart will most often flow a lot faster near the end.

photo by Juan Silveira.
My post with the long-steep AeroPress recipe is now publicly available here ! This is a recipe I had never seen elsewhere before which combines a fine grind size, very long steeps (10-15 minutes; sorry this is probably not competition-friendly), and the addition of water before the coffee to mitigate clogging (an idea recently discussed by Barista Hustle).

This recipe and some slightly modified versions have been my daily driver for more than a month now, and I find this method to be extremely useful for traveling ! I hope you enjoy it.
My next upcoming blog post is already available for my Patreon supporters here !

In this post, I describe some new understanding that I recently reached about the value of adding a source of hydraulic resistance below a coffee bed, and how a new upcoming device by Del Creatives makes clever use of this to transform espresso machines into single-serve filter brewers that can reach really high average extraction yields and offers impressive liberty on the desired beverage concentration !

I have been playing with this on my Decent and it has produced some of my favorite cups of coffee so far, with average extraction yields in the ranges 24-26% at any desired TDS between 1.5 and 3.0% or more (and I love the latter end of the range !)
I just released my last Patreon-only blogpost for full public access here:

In that post, I discuss how a device from Del Creatives shows potential to open new doors in the way we make filter coffee with espresso machines, and how I recently came to appreciate how a source of resistance below a coffee bed can be beneficial to reduce the impact of channeling.
I would highly recommend you follow @samosmrke if you are interested in learning more about coffee. Samo is a legit coffee scientist and consistently produces some of the highest-quality coffee-related papers I have read.

Lately, he also started posting some distilled and easy to read compilations about the current status of scientific coffee knowledge on his Instagram profile, and I find them delightful. I keep learning from him and I am sure you will too. We desperately need more people like this in the coffee world !
I have recently stumbled on @quantitativecafe ( and, a new coffee blog written by Michael Cooper that presents and carefully interprets amazing data from various coffee experiments focused on espresso but also useful for filter coffee. I know good data collection when I see it, and this is a case of great data collection. I was so excited when I found this page that I read all of Michael's posts in one go, and I loved it.

We definitely need more careful experimentation like this in coffee to understand what is going on ! I would highly recommend following @quantitativecafe and subscribing to his blog if you like this kind of stuff (and if you don't, I'm not sure why you are following me anyway 😆)
I'm excited to announce I will give a 3-hours live class on the Physics of Coffee during the 2022 Specialty Coffee Expo in Boston !

I will discuss my most up-to-date understanding of the physics in play in both espresso and filter coffee, and what this means for the best methods to brew coffee repeatably and achieve your desired goals. This class will include some brand new data and conclusions, new questions and predictions, and we will do a live demonstration of a new dripper prototype that I think will be both geeky home baristas' and WBC coffee competitors' dreams come true.

If you want to understand what happens under the hood of coffee brewing in an approachable yet deep way, I think you will love it !

I will also answer live questions during this course, and none other than Scott Rao will be serving you some very fine coffee for you to enjoy during the class !

More info and tickets available here :
My latest post about the mechanism behind astringency is on Patreon, and will become public in about 2 weeks !
I just published a new blog post on my Patreon ( about particle size distributions, with a discussion of how burr spacing, rpm, burr geometry affects them, and how to characterize different styles of particle size distributions. This is one of my most data heavy posts so far, thanks a ton to Weber Workshops for sharing their data.

If you are not subscribed to my Patreon, don't worry; the post will become 100% public in about two weeks.
I just published a blog post on my Patreon going deep into the analysis of 300 particle size distributions for 24 espresso grinders, with a number of observations that they allowed me to make. This was super informative to me and I hope it also is to all of you !

This post will become public at coffeeadastra relatively soon when I wrote another blog post (I have one coming up about Pulsar and SCA expo !)

Huge thanks to Kaffeemacher and ZHAW for gathering and sharing the data, and to Lance Hedrick for noticing the data set and letting me know about it !