Coffee making can be quite an involved and scientific process. Considering my love for control systems as an engineering challenge – an area, which would've been front and centre in my fallen through Ph.D. – I could hardly resist the challenge of making coffee live up to some desired spec.

I'm sure anyone who dared to venture into improving their coffee could attest to how deep the coffee optimization rabbit hole can be. Some might argue, they don't even make coffee for the coffee, or improve the coffee they make for the sake of having a nice cup of coffee, but the process of optimization itself is reward enough in and of itself.

For V60 and the french press I'm using James Hoffmann's abovementioned recipes, and I also learned a lot from his series on espresso making. I've also asked a bunch from baristas about their processes, who happened to be in a talkative mood during my numerous trips to cafés.

I could almost say coffee is more of an art than a science, but that might anger some, see Angela Collier's video about scientific glassware making on that one – art vs. science part starts at around 1:00:00.

Espresso

Now that tangents are out of the way, let's talk espresso. I have a VST 18g ridged precision basket, into which I dose 15–21 grams of coffee, depending on the type of bean and roast I have. I prepare the basket by putting a paper filter at the bottom (53 mm generic circular paper filter), a magnetic funnel on top, and dump the coffee into the basket. I then declump it with a WDT tool, 3D printed, nothing fancy; the fancy ones leave circular patterns on the bed anyway, and cause the grounds to pile up around the edge of the basket. Although, my working theory is that if one would make an automatic WDT tool with planetary gears which have relative prime throughout all of them, the circular patterns could be eliminated; but in my opinion it's not really worth the hassle.

Tapping the portafilter a few times, I then remove the funnel and temp. Securing the filter to the machin, depending on my mood, I either preinfuse the coffee or start brewing right away. I usually brew with my scale underneath the cup (or cups), and aim for a 2:1 product to beans ratio with a 25–30 seconds of brew time. Depending on the coffee, I might go higher up to 3:1, but that is really subjective and changes with what coffee I have, and also as the beans age. To be honest I don't usually notice difference with preinfusion, so I might need to experiment with that a little more.

Beans

I usually buy my beans as 1 kg bags when possible – for proven beans, that is – which could last long enough to go quite stale if left out on a shelf. So when I buy a bag of beans, I portion them out into Timemore vacuum canisters, of which I keep three. One of them goes onto a shelf in my coffee corner for ease of access. Another canister goes in the fridge so it keeps fresh longer due to the cold. The third one and the rest of the bag go into the freezer so it gases out or oxidises even slower.

The cycle usually goes like this: when the canister on the shelf is almost out, I take out the one from the fridge, which gets replaced by the one from the freezer. I usually let the cold ones thaw out before cracking them open to avoid condensation. The empty canister is refilled from the thawed out bag and then replaced into the freezer. Considering how much coffee I drink, a canister of coffee doesn't spend a lot of time out on the shelf, so it usually tastes quite fresh and just the way I like it all the way through.

Cleaning

One of the most important things one has to do, if they wish to have a decent coffee setup at home, is cleaning. When I first got the Mara, I cleaned the group head every week, just as the manual instructed me to do, but I shortly realised that I might be overdoing it. The thought always bugged me, that the instructions for the machine are really for those who operate the machine in a café, and to be honest, the parts seemed clean enough when I took them apart, so I don't clean it that thoroughly so frequently anymore. Instead, I started backflushing more frequently, which doesn't require nearly as much labour, and now I only take the grouphead apart around once a month for cleaning.

When it comes for descaling, it is a whole endeavour in itself, however. I think it was a bit more than a year after I got the machine that I decided it was time to descale it. I've looked around on the web for tips and suggestions, went over descaling products' descriptions to decide what befits my situation the best, and finally I decided on the simplest solution: citric acid. Most of the descalers are just dilute citric acid anyway, so I didn't see the point in paying a premium for something I can get much cheaper. Slight tangent: I have noticed that bottles of chemicals sold as household scale remover in grocery stores are just 10% hydrochloric acid, and cost more than household hydrochloric acid, which has 20% concentration, and this fact drives me crazy.

For that first time I tried descaling my machine I might've put a bit too much citric acid into the water, because after I allowed it to get hot and let it out from the machine, it came out with a really dark blue-green colour to it, which means it had high concentration of copper salts, which means it started dissolving the copper boiler, and that was really unsettling to see at the time, and I got a bit nervous about it. After a few refills and rinses, it seemed to have no issues, so I learned a valuable lesson about restraint, and also didn't break the machine; success! Nowadays I put way less acid into the tank and I let the water out as soon as the pressure is high enough, to avoid unnecessary wear. It still comes out with a faint shade of green though, but I take that as a sign that the built up scale has been removed entirely.