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?