How to Improve Espresso Extraction




  • Add a paper filter below your dose of ground coffee inside your group handle/portafilter filter basket.
  • Make sure there are no creases by pre-wetting the filter.
  • The paper mitigates uneven flow at the bottom of filter baskets.
  • Simple but effective - it will increase the evenness of water flow through the puck.
  • Thus improving and increasing your espresso extraction!


Adam Marley:

Hey, everyone. Welcome back to another tips and tricks with me, Adam. So this week we've got a short, shiny little hack and it has to do with making espresso. Some of you may have already encountered this, it's been going around the internet for a little while, but I'm going to call this 'the paper filter hack' - when making espresso. You can try this. You don't have to do it every single shot, and this is more so for making coffee at home, because it's not feasible in service if you're a barista. But it's fun to try out nonetheless. But the tip is to put a paper filter in the bottom of your Portafilter of your group handle, your basket, before you add the dry coffee in and pour your shot, make your espresso.

So you can find filters which are actually cut to be exactly the right size to just fit in neatly. What I've got here is an AeroPress filter, because well, they're everywhere. We have a lot of them. And then my sundry tip, what you'll find is, if you just try and put an AeroPress filter into the bottom of a Portafilter into a basket, it won't fit. It's a little bit too large. So what I do, is then I do place it in and you can see here, then place it in and then if you've got pre-infusion, perfect, just run a really gentle flow of hot water through the Portafilter, wetting the paper filter. You could probably just put it under the tap, I guess as well, that would work. And then the filter gets nice and soft and you can crimp it into the sides, push it against the wall.

You don't want any pockets or any bumps. You want the paper filter nice and flat and then push it up nice and smooth against the walls of the basket. What you'll find by doing this, is that you'll end up with a much more even extraction, even in the world's best baskets that are available, so let's say VST or Pullman baskets with really even whole distribution. And that is very important, even with those, just because of the way they're manufactured, they have to be this way, the holes you'll notice, they don't go quite to the very edge of the basket. That actually has a really big impact it turns out, on how even the flow of water is. If you're picturing the flow of water going through this way, down through the Portafilter, the flow around the outside, even with the best baskets, is going to be a little bit different to the flow, through the other areas of the coffee puck. That of course is going to lead to uneven extraction. The paper filter evens out the pressure difference.

Basically, I don't really understand the physics of it perfectly, but what it will lead to is it'll mitigate that issue of the holes not being perfectly to the outside, or at least help mitigate it, to quite significant degree, actually. And what that'll mean is that the flow will now be much more even around the entire circumference of the coffee puck. So yeah, your shots will be more even, you'll probably get a higher extraction. The outside bits will tend to have a bit of a lower extraction compared to the center and the paper filter hack helps to remedy that. So give it a shot. It is a little bit fiddly. Like I said, it's probably better for home, but I've noticed an improvement. I think it's worth the extra five seconds to put it in. Give it a shot, try it at home and let us know how you get on with it.

Thanks very much. See you next time.