More on the French Press Technique

November 15th, 2008

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!  ↩︎

Comment Policy

There are no longer comments on new posts. If you'd like to respond you can find me on twitter.