What is a pressurized filter, and should I use it for my espresso? I've just started out really using my Gaggia Classic espresso machine, and so far I've been pretty satisfied with my results – but I'm no expert. Yesterday, I lost the black plastic thing that goes between the portafilter and the basket (is that the right terminology?), as shown below:



Now, when I tried to make espresso without it, I noticed that the liquid would spray from the portafilter and, well, ruin my kitchen. When I researched further, it seemed that I didn't even use a normal filter, but something called a "pressurized filter", where there's only one hole in the bottom for the coffee to come out.

Here's what I found out about it on coffeegeek.com:


  […] a crema enhancing device is built into the actual filter basket, usually through the function of channeling all the brewed coffee through a solitary pin hole. This action creates a jet-like effect that boosts crema production, even in stale coffee or coarse ground coffee.


People on the internet seem to hate this thing though, and I start wondering whether I should get a replacement for this bolt, or just buy a "normal" filter. Here are my questions:


What exactly is the purpose of this "enhancement"? How does it work?
Why should I use it, or why shouldn't I? Does it matter for me as a non-professional?
This is called a pressurized portafilter. As you found on coffeegeek, it is designed to enhance production of crema. The Coffee Geeks look down on this device, since it produces what is essentially "fake" crema - even with old, stale pre-ground coffee.

If all you want to drink are lattes, it does not make much difference. If you want to taste decent espresso, then you must use a non-pressurized portafilter - even if you are a non-professional. 

Making espresso is not a slam dunk - especially with a consumer machine like the Gaggia. You will learn to improve your espresso shots by analyzing your technique. This often is based on the appearance of the crema during and after the shot is drawn. 

Since the pressurized portafilter gives you misleading information on the actual crema, you will have difficulty learning how to make a good espresso.