WEBER WORKSHOPS Espresso Paper Filters: Will They Improve Your Espresso?

We often advocate for a less is more mantra when it comes to espresso workflow; we like to keep it simple and use our keen knowledge of the fundamentals to guide us, yet there are times when the experiment bug bites us. Once we get that tinge, we’re incredibly persistent. We will stop at nothing to exhaust our palates fully, bedtimes be damned, and expand our frame of reference with new products in pursuit of better-tasting espresso. 

While using paper filters for espresso isn’t a new or revolutionary concept, the methodology is often muddled and often raises more questions than answers. For instance, Why add a paper filter when you’re already extracting through a filter? This question is especially relevant if you use a precision-cut basket like VST, IMS, or Pullman. What kind of paper filter should you use? Folks use several DIY options like cutting pour-over filters to size or employing their Aeropress filters to work double-duty. But most importantly, will this make my espresso taste better or different? Yes, it can, but how and what other variables are involved? 

Hypothesis and Experiment 

With some previous experience, research, and general knowledge, we propose that using a paper filter at the bottom of your portafilter basket will increase espresso extraction and impact flavor and mouthfeel in some way. As controls, we use Kickstep Blend roasted by our dear friends, The Great North. Kickstep Blend is a medium-dark espresso blend with a classic balance of bitterness, acidity, and sweetness from its cherry, dark chocolate, and caramel profile. Outside of an abundance of it in our tasting lab, we chose this coffee because it’s excellent at 1:1-1:2 ratios. Still, many of us don’t often drink straight shots that are this dark at larger ratios, so we thought it would be interesting to taste those results. For the paper filters, we’re using the Weber Workshops EPF with their Buck portafilter and 20g Unibasket. Here’s a simple experiment. 

• After dialing in to our recipe specifications, we will pull one shot without a paper filter and compare it to a shot extracted with a paper filter. We will pull shots at 1:1, 1:2, and 1:3 brew ratios. 
• We hypothesize that the paper filters will increase extraction and give us shots with more clarity of taste, making the espresso more drinkable and “smooth out” shots at higher brew ratios. We think the paper filters will be more beneficial at higher brew ratios, but will they be for tighter ones? 
• A refractometer will help us measure the extraction percentage of shots pulled with and without a paper filter. A refractometer essentially tells you how much coffee is in your coffee.

The Unique Characteristics of Weber’s Espresso Paper Filters 

The EPF is an exclusive collaboration between Weber Workshops and the Japanese manufacturer CAFEC. The EPF is much thinner than most other filters at around 0.15mm thickness, making it ideal for espresso use. Using Aeropress filters, for expample, could be holding too much flavor back. The critical difference in the EPF is the paper's processing method. CAFEC employs the wet crepe method, making water flow through the paper faster, more stable, and even across the filter's entire surface area. This provides several benefits for extraction: 

• The paper filter prevents the portafilter basket's filter hole from clogging during brewing, resulting in more even extraction. 
• This allows you to grind finer, enabling higher extractions without channeling or clogging. 
• As a result, a slight gap forms between the bottom of the espresso puck and the portafilter basket, allowing optimal flow through the coffee bed. The wet crepe method used in manufacturing the filters is the catalyst for producing a superior filter.
• The paper filter prevents larger fats and solubles from entering the cup, resulting in a cleaner, crisper cup without compromising the body of the espresso shot. 

Experiment Results 

1:1 Brew Ratio (20g in / 30 sec / 20g out)

It took a lot of work to parse out a significant difference between shots pulled with paper filters and without. We did notice that the shots pulled without a paper filter generally had more of a bite on the back end and left more of an aftertaste, whereas the shots pulled with a paper filter had a more rounded and pleasant finish. A 1:1 brew ratio is already potent on its own; thus, ultimately, we had a difficult time differentiating between the two shots. Both were tasty. It’s well worth repeating this same experiment with lighter roasted coffees. 

1:2 Brew Ratio (20g in / 30 sec / 40g out)

There was more of an immediate difference in flavor between the 1:1 brew ratio and the 1:2 brew ratio. You still get the brightness and upfront acidity from the unfiltered shot, but the paper-filtered shot tames that initial bite and mutes its lasting effect, making the shot a smoother drink. The mouthfeel is much cleaner with the paper filter, and it drinks more like a filtered cup of coffee while still having the body of espresso. 

The results raise a few more questions. Does the filtered shot with the 1:2 brew ratio taste clearer and have a more pleasant finish because of the fats and larger solids left back from the filter? Or is the difference in particle size (slightly coarser or slightly finer) related to extraction results while maintaining the same recipe? Or is it a combination of both? Perhaps the 1:3 ratio taste test will give us some answers. 

1:3 Brew Ratio (20g in / 30 sec / 60g out)

Part of our initial hypothesis was confirmed. Using a paper filter at a higher 1:3 brew ratio—not only increased the extraction yield, but the refractometer results confirmed a shocking upfront difference in flavor 7.95 TDS (no-filter) vs. 8.3 TDS (paper filter), which seems like a small change, yet, the Kickstep shot with the filter smoothed out the back end of the shot, made it easier to drink at a higher yield, almost like pour-over mouthfeel vs. a French press mouthfeel. As for taste, the stone fruit note of the cherry was more immediately apparent, and we were able to differentiate that from the caramelized sugars and the bitterness of the chocolate, which made the shot more pleasurable to drink. Ultimately, we’d rather try lighter and more delicate coffees at a 1:3 ratio, but we were not disappointed in the results or taste. 

While the paper filter experiment was limited to just one coffee, the results illuminated the possibilities for an expanded research experiment, including using lighter roasts and more delicate varietals and using different grinders, baskets, and brew ratios. For anyone interested in brewing espresso at larger ratios (1:3), adding an EPF to your workflow is an easy, affordable, and worthwhile addition to your puck prep. Not only did we find that it increased extraction at higher brew ratios and allowed you to grind finer, but it also improved flavor. Although we didn’t discern significant taste differences from the 1:1 brew ratio, we still think this bears further experimentation with different coffees. Remember that if you get a Unibasket, it comes with a pack of paper filters and a puck screen (another video about puck screens is in the works). Don’t forget to add the EPF Dock to your espresso bar to house the filters. 

Do you use a paper filter in your espresso workflow? If so, is it the EPF or another version? If you copy our experiment, sound off in the comments; we’d love to hear your results.