Pressurized vs. Non-Pressurized Portafilters

Portafilters come in many sizes, shapes and styles. The aesthetics can vary (e.g. handle wood/color, single spout/double spout), and so too can the functional design (e.g. size, basket/naked). One of the most fundamental differences in portafilters is whether they’re pressurized or non-pressurized.

How Espresso is Made

At its most basic, espresso is brewed by extracting emulsified coffee oils under pressurized conditions. This results in flavors that no other brewing method can quite replicate.

The pressure required for brewing espresso is generally 8-9 bars. Pressurized portafilters generate this pressure with a double-wall structure that restricts the flow of brewed espresso. Non-pressurized portafilters generate this pressure by using finely ground coffee.

The difference in how pressurized and non-pressurized portafilters generate the 8-9 bars of pressure fundamentally affects the coffees they require and the espresso they brew.

Steam-powered espresso machines generate much lower pressure, often up to 3 bars. This makes strong coffee, but won’t create the flavor profiles of either pressurized or non-pressurized portafilters.

What is a Portafilter?

The portafilter in its strictest sense is the part of an espresso machine that holds the grounds basket. For the purposes of pressurized vs. non-pressurized portafilters, the portafilter and basket can essentially be thought of as a single component.

The most traditional portafilters have a handle, and a cup with a spout. The grounds go in the basket, the basket goes in the cup, and the portafilter goes onto the group head.

Some newer espresso machines have non-traditional designs. Consider the Uniterra Nomad’s drawer, somewhat common naked/bottomless portafilters, El Rocio’s prototype clear portafilter, and Fundamental Mode’s insulated portafilter.

Despite the various innovations (which haven’t all been brought to market), the fundamentals of these portafilters remain the same. They hold a basket of grounds, allow water to flow in, and allow brewed espresso to flow out through either a single (non-pressurized) or double (pressurized) screen/hole.

What is the Difference Between Pressurized and Non-Pressurized Portafilters?

Pressurized and non-pressurized portafilters differ in how they generate the pressure they brew espresso with — more specifically, whether the portafilter itself generates the pressure.

Pressurized Portafilters Brew Strong Espresso

Pressurized portafilters are so-named because they create the pressure themselves. They have a double-wall structure, where there is a:

  • Basket with holes
  • Gap of space
  • Bottom with one hole

The single hole restricts the flow of espresso, so that it collects in the space as it exits the basket. This creates back pressure, which is how the 8-9 bars are generated with a pressurized portafilter. 

The backpressure is thus created after espresso is brewed, and enters the basket in the reverse direction of how the water flows. This creates something that’s much like traditional espresso — but isn’t quite the same. 

A pressurized portafilter will make strong espresso and faux crema. It’ll work with virtually any coffee and a range of grinds.

Gaggia Classic Pressurized Portafilter

Non-Pressurized Portafilters Brew Vibrant Espresso

Non-pressurized portafilters have no structure that generates backpressure. They have a single-wall basket that drains directly into the portafilter’s spout, or a cup in the case of bottomless/naked portafilters (which are non-pressurized). The spout on non-pressurized portafilters merely directs the flow of espresso, and doesn’t restrict flow or create backpressure in any way.

With a non-pressurized portafilter, the 8-9 bars are generated by forcing steam through finely-ground coffee. The fine grounds restrict the flow of water and create the pressure.

Thus, the pressure in a non-pressurized portafilter is created right within the brew basket. This actually changes how the espresso is brewed — more of the emulsified oils are extracted, and extracted gasses create crema.

What is Crema?

Crema is the topmost, lightest layer in an espresso shot. It’s nothing more than aerated espresso that has miniscule bubbles in it, although it does impact the flavor of espresso.

Espresso that’s brewed with non-pressurized portafilters has true crema, as gasses (mainly carbon dioxide) are extracted and create miniscule bubbles in the brewed coffee. These gasses naturally rise to the top of the shot, and eventually dissipate if left alone.

Pressurized portafilters try to replicate crema by aerating espresso with pressure after the coffee is brewed. The aerated layer can be seen on the top of a shot, and may even be thicker than with a non-pressurized portafilter. It’s faux crema, however, and doesn’t impact flavor in the same way.

54mm Coffee Bottomless (non-pressurized) Portafilter

What Are the Advantages/Disadvantages of Pressurized and Non-Pressurized Portafilters?

The advantages and disadvantages of both pressurized and non-pressurized portafilters can be summed up with two categories: quality and flexibility.

Non-Pressurized Portafilters Extract High-Quality Espresso

Non-pressurized portafilters are the only way to brew true, high-quality espresso. There’s no artificial way to replicate generating pressure directly in the basket, and there’s likewise no other way to replicate the aromatic, flavorful vibrancy that shots have.

When properly executed, a non-pressurized portafilter will pull out flavors that no other brew method — including pressurized portafilters — can match.

Pressurized portafilters make something like imitation espresso. Shots from these portafilters can be rich, strong and more flavorful than other brewing methods. They’ll always fall flat of the liveliness that non-pressurized portafilters have, though.

Pressurized Portafilters Are Forgiving

Pressurized portafilters are much more flexible in the grounds that they use, and they’re much more forgiving if you have mediocre equipment, make a mistake in tamping or use old coffee. 

Because pressurized portafilters themselves generate pressure, they aren’t as reliant on grind size and tamp. You can even use a generic burr coffee grinder and still get decent brews from pressurized setups.

For consistently good espresso under a variety of non-ideal variables, pressurized portafilters will deliver good shots. 

Should You Choose a Pressurized or Non-Pressurized Portafilter?

Whether a pressurized portafilter or non-pressurized one is best for your personal use depends on your coffee setup and desired beverage. They each are useful in different situations:

  • Want the Best Espresso: If espresso quality is your preeminent concern, a non-pressurized portafilter will deliver the best results (assuming you pull shots correctly).
  • Want a Hands-On Experience: A non-pressurized portafilter is better for hands-on dosing and tamping, as your skill in these aspects will directly influence the quality of the shot. Preparatory work matters much less with pressurized portafilters.
  • Have Only a Coffee Grinder: A pressurized portafilter is forgiving enough to pull good shots with even a budget burr coffee grinder — no espresso grinder is necessary (although one helps). 
    If you have a non-pressurized portafilter, you’ll struggle to pull drinkable shots without an actual espresso grinder. Coffee grinders aren’t precise enough to dial in the grind, and you’ll have problems with channeling (water creating channels in the grounds).
  • Have Old Coffee: Old coffee beans can be used with either type of portafilter, but the beans won’t have as many exotic flavors to extract. The difference between a pressurized portafilter’s and a non-pressurized portafilter’s will be dampened.
  • Fresh Single-Origin Coffee: Likewise, fresh coffee beans can be used with either type of portafilter (and are always preferable). A non-pressurized one would be able to extract the coffee’s fine flavors slightly better.
  • On a Budget: Many budget home espresso machines have pressurized portafilters. While they might not be the most stand-out machines, they’re certainly capable of pulling decent shots. A pressurized portafilter machine is worth consideration if your on a budget — and certainly preferable to a steam-powered machine that has low pressure.

Using Pressurized Portafilters

Using pressurized portafilters is fairly straightforward, and the learning curve on these is less than what non-pressurized ones have.

Should You Tamp a Pressurized Portafilter?

A pressurized portafilter must still be tamped, although the tamp doesn’t have to be absolutely even. Packing down the grounds provides some initial resistance, and ensures that they don’t float around when the basket fills with water. The portafilter’s backpressure will help mitigate uneven tamping, though.

What Grind Should You Use With a Pressurized Portafilter?

Pressurized portafilters can accommodate a wide range of grinds, both in terms of grind size and grind consistency. 

Try using a medium-fine grind setting as an initial starting point. Something that’s finer than what you’d use for automatic drip brewers, but coarser than a traditional espresso setting. A traditional espresso grind will fill up the space gap with grounds and clog the portafilter.

Additionally, you don’t have to purchase a high-end grinder when using a pressurized portafilter. While improving grind consistency will always improve brewed coffee quality, these portafilters can accommodate inconsistent grinds because the grounds don’t generate the pressure.

Should You Preinfuse When Using a Pressurized Portafilter?

Preinfusion services multiple purposes. It helps prevent the topmost grounds from becoming loos when water enters the basket, releases some carbon dioxide (too much of which can turn espresso sour), and helps ensure more even extraction.

All coffee can benefit from preinfusion (bloom with brewed coffee), and pressurized portafilters are no exception.

Using Non-Pressurized Portafilters

Non-pressurized portafilters require more attention and practice, but their espresso is delicious once you perfect the technique.

Should You Tamp a Non-Pressurized Portafilter?

A non-pressurized portafilter doesn’t just have to be tamped, but the tamp has a direct impact on espresso extraction. The compact grounds are what provides the resistance to build up pressure. Tamping at an angle, insufficiently or too much can all interfere with pulling a shot.

As a general guideline, tamp non-pressurized portafilters to ~30 pounds (can vary) and make sure the tamp is even.

What Grind Should You Use With a Non-Pressurized Portafilter?

Non-pressurized portafilters require fine grounds, and the exact size and consistency of the grounds can have an oversized impact on extraction. Start with grounds that are just coarser than what’s used for Turkish coffee. You’ll achieve the best results if you use an espresso grinder that can make minute adjustments, and is precise within the finer grind range.

Should You Preinfuse When Using a Non-Pressurized Portafilter?

Preinfusion is important when using non-pressurized portafilters. It helps keep the grounds on top from being distributed, reduces channeling, and aids in general extraction.