Peoples Coffee

When it comes to plunger coffee, everyone knows best.  If you’ve ever been dive-tackled as you go to plunge the coffee, or had a spoon wrestled from your grip mid-stir, then you’ll know what I’m talking about.  I’m a big fan of plunger coffee, but it has certainly tested more than a few relationships over the years.

Which is why I decide to spend an hour studying the secret art of plunger coffee with someone I’d never dare argue with – Peoples roaster and human encyclopedia of coffee, Rene.

He begins by introducing me to the holy trinity of plunger coffee: grind size, brew ratio and water temperature.  While every step of the process is important, varying these three factors will affect the taste of your coffee more than anything else.

So let’s start with grind size: Coffee should be ground much coarser for a plunger than for an espresso machine, to a gritty sand-like consistency.  And it goes without saying that you should grind your beans fresh each time.
“Coffee degrades when exposed to oxygen, so you should use it within about a minute of grinding.”

Water temperature is also key.  You shouldn’t use boiling water straight on ground coffee, as it produces bitter and sour flavours. To cool the water down, either let the kettle sit for three minutes after boiling, or pour it into another vessel before pouring it into your plunger.  (I know, waiting is not my strong point either.  But trust me, the coffee will thank you).
Once you’re ready to pour, half-fill the plunger and give it a good stir (but not for more than ten seconds, says Rene). “By stirring it you’re activating more infusion and encouraging that extraction of flavour.”
Let it sit for a moment, then pour the rest of your water in and leave it to brew for another three minutes before serving.

Now for the big one: brew ratio.
I’ve spent the last five years heaping coffee into a plunger like the world was about to end.  But this is one of those times where less is more.

To prove the point, Rene makes two plungers, one with 18g of coffee and one with 20g (to 300mL of water).  And although it’s only a matter of grams, the contrast between the two brews reaches up and slaps me in the face.  The 18g brew is much lighter and fruitier.  The 20g brew has a stronger coffee taste, and while delicious, it‘s definitely missing the more subtle flavours of the first cup.

“The golden rule is one part coffee to sixteen or seventeen parts water,” Rene tells me.  But how is the average person supposed to figure that out?  Simple.  You use scales and a calculator.
“It’s geeky, but if you want to have a perfect cup every day, you’ve got to use them,” says Rene.  “I’d like to arm all the people who are passionate about coffee with a set of scales.”
(You can pick up a set at the Constable St store).

Rene is an exceptional sort of coffee geek, so if you’re not quite there yet, then he recommends you at least weigh it once to see what it looks like in a measuring spoon.  Then measure the water into the plunger and see where the level rises to.  From then on, you should stick to those measures like your life depends on it.
“It’s important to do the same thing every time, unless you’re experimenting.  If you’re not aware of what you’re changing, you’ll never be able to replicate a good cup.”

So there you have it.  Plunger coffee 101.  Any arguments, see Rene.

(Or you could leave him a comment, below)

December 14th, 2011

Posted In: Brewing, Coffee



  • Lizz says:

    Phew – and now Im thinking I better go and buy these scales!

  • Hadassah Grace says:

    Nice one.
    I much prefer to pour all the water in at once, then gently push the crust of grinds under the surface of the water with the back of the spoon. This prevents an uneven extraction, and reduces the chance of inconsistent brews, since it’s hard to make sure you’re stirring the same every time.
    Also, to measure your water, you’ll either need to rest the whole plunger on top of a big set of scales, or pre-measure your water before pouring.
    I’m also a little sketchy about cooling the water down for a whole three minutes before pouring. I guess if you’re keeping it in the jug, it might take that long to cool down, but the water will cool as you pour, and continue to cool as the plunger brews, and stirring aggressively will cause it to cool also. If you’re leaving it a whole three minutes, the entire brew is likely to be less than optimal by the end of it. I’m usually much more concerned with keeping things hot, especially if you aren’t going to pre-heat your plunger (which I assume you don’t, since there was no mention of it).

    • René says:

      Hi Hadassah, Thanks for your response, this was more aimed at the general home coffee maker, rather than the experienced barista geek (like yourself). Preheating your plunger is definitely a benefit, as we do want temperature to stay in the 85 – 95 range. I do it, and I do recommend it. But we thought there must come a time when the home coffee maker says “enough of all this geekery!” and it was dropped from the long list of preparation guidelines due to word limit constraints!
      I’m not sure (as a rule) if your “pushing with a spoon … prevents an uneven extraction” or gives any more consistency than stirring, (as I’m sure it’s possible to inconsistently stir, or push with a spoon!) But if the coffee is fully saturated, then great, thats the goal!!
      When I am making plunger it’s usually a full and large plunger with 1 litre of water. The bloom makes the grinds overflow, so using half amount of water to start with stops this from happening, and allows a good stir without spilling. I do believe a short thorough stir (not aggressive) ensures complete saturation of grind, but should be kept consistent brew to brew.
      In my mind, the danger of stirring would be to cause over-extraction (as well as temperature loss), but I would rather take this risk and have all the grind thoroughly extracting from the beginning. Another way to ensure thorough saturation is to pour from a height onto the bed of coffee, this can be a great way of achieving saturation, but (as my shirts will attest) is sometimes messy.
      I believe for “pour over” (filter style), agitation has much more impact on extraction rate than in a plunger, as contact time is shorter, and there is a lot less water to coffee at any one time. So to this end I am much stricter on pour-over on this issue.

      My experiments give a drop in temp from 99 to 95 degrees during the 3 minute wait for the water to cool in jug before pouring onto coffee. Around another 10 degrees will be lost during brew, and will then be in the low 70s once it reaches the cup. I find coffee in the 60 degree range suitable to drink, and find the best flavours once it has cooled to the 40 degree range.
      As a rule, when experimenting, I simultaneously make one brew as per normal, and one test brew, and taste them “blind”. Side by side comparison is the best way to gauge the preference in flavour differences between brews.
      At the end of the day, the goal is for it to taste good to you, using your brew equipment.

      Coffee geekery is great, but be warned, the more you dig, the deeper the hole gets.


  • Eileen Turnbull says:

    Gold !
    I always let the water cool down for 3 minutes (in the jug letting it cool to just over 90 degrees )before pouring into the plunger, otherwise It will taste burnt and bitter.
    Its simple,practical advise for everyone:)
    Ren being the wizard of coffee that he is, has nailed it .shot

  • Jenny Ryan says:

    This is brilliant…have been weighing my coffee all week and it’s been perfect every time. Do you reckon you could do a stovetop espresso post at some stage?? still struggling to make mine perfect. thanks!

  • Arnaud says:

    This page has forever changed the way I make plunger coffee. My life will never be the same again.

  • Devin says:

    Great article! I have a good set of kitchen scales. I think I will go about setting them to work!

  • GZ says:

    Once you add all the water and wait for it to brew for 3min. What would be the ideal method of plunging? Once ? Twice? And do you go fast or slow?


  • Kelda says:

    I’ve been told (and it seems to work) that instead of stirring the grounds, and pouring half and half, to pour all the water in, and sit the plunger JUST on top of the grounds, so that ALL the grounds are submerged just under the water’s surface.
    What’s your take on this?

  • Alan latham says:

    I just measured 18 grams of coffee using my coffee measure. It was 4 scoops. 300 mL water is just under 12 ounces. That is two coffee measures per one cup of coffee! Really strong in my book. Are you sure about your ratio? 20 gm / 300 mL is 15. So by your scale, this is a weak ratio.

    • Rene says:

      Hi, we still use 1:16 as a starting ratio for most brewing, so for 300g of water you will want around 18g of coffee, we then often round down to 1:17 to achieve more fruity flavours. The 20g to 300ml was used in the blog to illustrate that too much strength comes with a cost of reducing good subtle flavours which add to differentiation between coffees. cheers

  • Rajpal says:

    Rather than waiting for the boiled water to cool down, why not just add a little cold water to the jug?
    Quick result, right?
    Liked the article, thankyou .

Leave a Reply

Your email address will not be published. Required fields are marked *