The importance of being wrong

I feel it is about time I broached this subject.  With an eye to the last posts, as well as to the response to my Chemex videocast, I feel the need to make something very clear.

The internet is full of information, though it is also full of keyboard heroes, and has something of an issue with its signal to noise ratio.  Identifying who is a useful purveyor of information is tricky and, while there is growing use of indicators in forums, often it is he who shouts loudest that wins.

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The Marco Über Boiler

This will probably end up being quite a long post, and sorry for being a bit cryptic on here the other day.  I want to explain the history of this little project, and give credit where it is due.

This morning I got up early to fly over to Dublin, to the CatEx show there.  Apart from catching up with Stephen, and lots of other lovely coffee people, and catching a little of the Irish Barista Championship, I was really there to see the guys at Marco and the new machine they had on their stand.

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The best feeling in the world

Everyone tells you how hard it is to start your own business, and you only really get what they mean once you are neck deep in it all. But this isn’t a complaining post – quite the opposite.

Gradually, over the last few weeks and months, I have realised that I am really, truly learning again. It is a great feeling. Competition used to be my way of stepping back and being forced to reassess what I did and why, and my year as champion had amazing bursts of learning such as origin trips.

Back at work again it has been a pleasure to start to develop my palate all over again and start to work out what I am tasting when I pulling shots. I’ve never really able to taste as clearly what a particular coffee is doing in a blend, or to understand exactly what a coffee brings to a blend when pulled with all the variation that humans (especially me!) bring to brewing. All of this is a great reminder that I have such a long way to go, and I love this part of the process.

I also realised today that my Chemex brewing technique has been slipping and I am not getting things right – time for a grind reassessment, as well as a technique check. I am losing the top notes and I want them back!

In other news I have no idea how coffee suppliers stay trim, as I am already starting to worry about my inability to refuse delicious treats when dropping in. Looks like I will have to take up some serious form of exercise!

TDS, Chemex and London’s terrible water

So thanks to the lovely people at Bunn I have a couple of TDS meters and have begun to poke them into various coffee drinks.

The first thing that upset me was just how hard London’s water is. Out of the tap I get 410ppm, which is pretty hard. This means it is not ideal for brewing coffee as it is less “hungry” for new solubles than softer water. I didn’t realise until I started testing just how badly it was affecting the coffee.

Chemex and TDS

Testing some of Tim’s coffee brewed on the skinny Chemex

I was struggling to get into the Golden Cup zone of 18-22% extraction which, through years of filter brewing, is considered a suitable target. Different countries might like different strengths of coffee but they all generally like 18-22% of whatever dose that is.

I have know switched to bottled water for brewing (with a much more attractive TDS of 130ppm) and the coffee does indeed taste much better and my extraction percentages are up even though I haven’t changed the grind or dose. I had gotten used to a very coarse grind on the Chemex (after being advised by Kyle in but have slowly been bringing it finer to get the percentage up. I will keep doing more but wonder how many other people out there have TDS meters and whether they have compared their brewers with different grinds and doses and compared the cups after.

To this end I’ve done a little spreadsheet that negates the need for a brewing chart as the maths is built in. It works on 2ml of water being absorbed by each gram of coffee but you can change that too. Input the amount of coffee you use, the amount of water you brew with and then TDS measurements. I’ve left columns in there for other useful data – such as brewer, coffee used and notes on grind settings. I probably should have found a way to include a cupping score/notes but haven’t. If anyone else fancies having a go then do download it and let me know how you get on. Once I have enough data I will post up about my Chemex experiments.

Thoughts and comments welcome….

XLSTDS Testing Spreadsheet


Mike Khan from Bunn sent me his spreadsheet which does percentages and graphs for each brew you do.
XLSMike’s TDS Calculator


Thank you Mike!

The Bodum Kona

After the Midlands UKBC heat Anette and I drove over to Steve Leighton’s to spend the afternoon at Hasbean. After chatting about brewing kit for a little while Steve very kindly gave me a Bodum Kona to play with.

Now I love my Chemex – it is my comfort brewer at the moment, though the vacpot is getting tempting (I just worry about committing to the technique to raise myself to the level of the barismo vac brewer kung fu). However I can’t stop worrying about the paper. I rinse religiously, and often wonder what it is keeping out of my cup (for good or bad).

Bodum Kona

Brewing some fine coffee this morning

What threw me is something I hadn’t considered up until this point – the way that the paper affects the flow of water through the coffee. I haven’t brewed much in the past with gold/titanium filters so I put my hands up as inexperienced. As I’ve said previously I have been using a much coarser grind with the Chemex, but the Kona has taken me a fairly long time to dial in the grind as the metal doesn’t provide the same resistance to the water that paper does. To get a decent brew time I had to grind finer than seemed right, and the cup was indeed a bit ropey. I am still not entirely convinced I’ve got it but I did get a very sweet cup from the Collective’s Daterra Sweet Collection.

I am brewing at 60g/l at the moment and would appreciate any input from people a bit more comfortable/experienced with them than me. Also I’d be curious if people have any particular techniques for pouring the water.

Brew Temperature and the Chemex

I remember reading early in my coffee days that someone had done an experiment where they had compared heat loss in porcelain espresso cups of different thicknesses and found that the heat retention of the porcelain didn’t much matter because all the heat went out of the top anyway. Like a lot of what I read on the internet at the stage I didn’t question it, didn’t want to see data but instead found it interesting, tucked it into its little trivia box in the brain and moved along.

After some comments in the thread about using scales to brew my Chemex on brew temperature I decided to perform a few rounds of experiments. Simple really, I just placed a probe (K-type, not ideal but it will do) into the bed of coffee, poured over the water and waited to see what would happen. The first test gae me an unexpected result.

Brew temperature of a Chemex

Brew temperature of a Chemex

What I expected was a steady decline in temperature during the extraction, and over a couple of minutes losing a fair few degrees, due to the area of steeping coffee being quite large. When the probe was in at the top of the brew the total heat loss was about 2C. Not much at all. What was interesting also was the temperature gradient throughout the liquid. At the start it was a couple of degrees from the top of the brew to the point of the filter cone and over brewing that stretched out to about 4 or 5C.

I’ve only done this experiment a few times so if you have the kit and a few extra minutes to spare I’d love to see it replicated – the coffee coming out isn’t much affected by the probe so it isn’t a wasted cup in the morning.

To completely and utterly hypothesize – it seems the floating crust of grounds does wonders for insulation, possibly with the help of CO2. In the next round I’d be tempted to stir and skim like a cupping bowl to see if this accelerates the cooling.

Thoughts anyone?

My increasing reliance on scales

These days I drink relatively little espresso (compared to my total coffee intake). Most of the time it is the Chemex or the press.

I am pretty much a 60g/l kind of person when it comes to brewing and, after I was rightly schooled by Kyle Glanville whilst in LA, my grind for the Chemex is pretty coarse. However I just can’t let go of the obsessive chasing of detail. The moment’s where things just come together by mistake are few and far between for me, so I obsess. I tend to use a larger Chemex so when I only want a large cup it bothered me that I didn’t know visually exactly how much water to add, or when I had added enough without guesswork. And guesswork just won’t do. So now I tend to put the chemex or press with the coffee in on a scale, tare it off and then pour the correct weight of water. I dislike transferring water from kettle to measuring jug to brewer so this seems the only sensible way.

Weighing a chemex

It seems so obvious – and whilst no one told me to do it like this surely I am not the only one? Is this too geeky?

Thoughts on the Chemex

After giving in to the curiousity caused mostly by Tonx‘s postings on it, I bought a Chemex. Before it arrived it turned out Anette had bought me a bigger, better version. Which was a pleasant surprise.

It has become my standard way of making coffee at home if I am relaxing or working. Part of the slightly unscientific way in which I use it bugs me. I am never really quite consistent with my dose, and the period of time where you soak the grounds in a little water (the “bloom” as Chemex likes to call it) varies a little as well.

This afternoon's Chemex

I like the coffee I get out of it very much, and it is a very pretty vessel. It could just be the coffees I am using with it but I do tend to get cups with great mouthfeel, lovely sweetness but often not quite the nuance and character I know the coffees are capable of. Don’t get me wrong – I love the coffee it makes, yet I worry I am doing something wrong or am missing a trick somewhere. That or maybe that’s just the kind of coffee it makes.

Comments from fellow Chemex owners very welcome. What kind of dose/grind are you using?