More on the French Press Technique

After the last post there was a bit of discussion about this method.

One big question was:  “Why break and then skim?  Why not just skim?”

This seemed like a pretty good question to me, so today I decided to do a few quick tests.

I took two identical presses, the same dose of coffee, the same brew water, temp and time and then after 4 minutes broke and cleaned one, and just cleaned the other.  I then tested out the TDS in each cup of coffee.

A TDS meter is useful, but limited.  It will tell you how much is dissolved in the water and nothing more.  Here I wanted to see if one cup was stronger than the other.  It turns out one was – and by quite a significant percentage. 1

The broken and stirred cup was stronger, usually by around 0.2%.  This doesn’t sound like much but when you do the maths backwards you find that it is a swing of about 3% of the ground coffee solubles extracted into the cup.

I want to do some more tests on this, and I want to do some blind cupping of it as well.  However it would seem that if your grinder produces a lot of fines, and when making press coffee it seems to easily overextract then I would just skim, opposed to breaking and skimming.  It could be that a different dose and steep time could yield better results.  I am waiting for Mark Prince’s article on his press technique because I know that while he skims but doesn’t break he does use different parameters.  It may be that one style might highlight a certain coffee better than another, who knows – I am just interesting in learning more about all this.

  1. It should be noted that I haven’t done this experiment enough times for it to be seriously useful – if anyone out there with a TDS meter wants to contribute then please do!  ↩︎

18 Comments

  1. Hi Jim.

    Two articles are coming out about the technique I use, which was based on hearing Tim’s method over a year ago, albeit second hand (and right up until a few weeks ago, I thought the method I used was identical to Tim’s).

    The first is Karen Hamilton’s article about our October tasting event, where I gave two tutorials on press pots, a beginner and an advanced. From her article (which hopefully will be live by Monday):

    The basic French press walkthrough met with enthusiastic applause. But Prince did not stop there. For the more adventurous, he demoed a “stir and scoop method” where an additional 2 grams of coffee are added to the typical 7-gram dose of grounds (per “cup”). The grinds are agitated and the plunger is ignored until the very end; a saucer is used in its place throughout the steeping time, and two spoons are used to scoop off the grinds before the plunger is finally applied and pressed, and the brew is poured.

    That was Karen’s interpretation, which is fairly accurate. I updose about 2 grams to account for the differential in TDS, but steep a bit less time (3 minutes after the various stirs and pauses) – mainly to account for the approx 1+ minute of starting time on the brew.

    It does help produce a much cleaner cup. My palate is still fe’ked right now from getting over the flu, and I’m dying to try Tim’s exact method head to head with this one.

    The second article is a how to on this technique and Tim’s technique – I’m just waiting for some interview question responses from Tim before putting that one online.

  2. Great Video. I love RJD2. Scooping is a great addition to my repertoire, but I guess my question is simply why French Press makers produce such widely-spaced screens to begin with. I’ve been using a nylon mesh filter for the past couple of months (inserted into the existing filter on my French Press) and the difference is huge. It might not be quite as clean as scooping out the grounds, but what I get is a fine silt rather than any sludge. It reminds me of the fines I get in Clover-brewed coffee although the coffee comes out a bit creamier. Now I need to go try scooping with a nylon filter.

  3. The weird thing for me is that every time i go and break the crust, i et even more resistance by the bottom of the pot. It seems that the grinds kind of sink, but by the time i’m half way done plunging the resistance increases a large amount. There also seems to be even more sludge then when i don’t break. I think I’m an anomaly, but want to know if anyone else experiences this, or maybe i just suck at the technique.

  4. Kudos to you, James, for taking the time to accurately measure the things that CAN be easily measured (dose, brew ratio, TDS, etc) before speculating on the things that CAN’T easily be measured (taste, aroma, body, etc). If more people would do this, we’d be a lot further down the path to quality coffee (IMHO).

    Turbulence = increased solubles yield = a different flavor profile, don’t you think?

  5. Hey James, before making any conclusions, I would first look to the range of accuracy for the TDS meter. From what I’ve heard, it’s not too good…your experiment may have just measured random statistical deviation. Just a word of caution…

  6. Hey Brendon.

    The range of the meter was 0-2.00%, and I had just calibrated it. I am very aware that cheap TDS meters are useless generally speaking, and one day hope to afford a proper one!

  7. Hey James,

    I just tried out this technique today, and it definitely produced a cleaner cup than I’m used to with a french press. However, I wonder about that crust of coffee sitting on top of the press (just as it sits there when we cup). Aren’t the solubles from the crust not being extracted? And when we break and allow the coffee to once again come in contact with liquid, won’t solubles begin flowing into the liquid? What do you think?

  8. There is a technique to measure the TDS of coffee, water and the amount to be dissolved in the water. However, the technique is not available everywhere.

  9. Hey James – (and Matt)

    Tried the technique a few times throughout the week and liked it a lot, I will have to try some more comparisons to come to any sort of real conclusion however.

    That being said I too am having the same thing happen as Matt. While I normally wouldn’t get much (if any) resistance, the bottom half of the press jams every time I’ve done it. Could be a number of other things as well of course.

  10. Hi George – can you tell me what grinder you are using? You may benefit further from the straight clean without the break first.

  11. We use one of the R2D2s, can’t remember what model/year off hand though.

    Tried the straight clean today and it was much easier to plunge, and very nice indeed.

    Have you ever considered plunging a cm or 2 during steep time so that the bloom is completely immersed under the water, and thus being extracted like the rest of the coffee?
    (Read this in Scott Rao’s professional barista handbook)

  12. What about mixing right away before letting it sit? This breaks up the bloom, but gets the grounds mixed into the water better.

  13. Wow it's crazy how detailed you've gotten into these advanced brewing methods! Definitely will be coming back to see what else you come up with.

  14. Do you accept guest articles or blog posts? I just like the taste how you wrote More on the French Press Technique, I am in this topic for ages and I would love to write couple material here in case you agree.

Submit a comment