Ever since I got serious into this espresso thing, I’ve been using two tools to prepare my grounds in the portafilter – a distribution tool, and a tamper. I wasn’t really sure about the voodoo power of either at the time, and bought cheap off Amazon, rather than the expensive branded versions. They didn’t come with instructions, and I assumed I would ditch one or the other once I had found the best process for me.
Some people say you don’t need both the distribution tool AND the tamper, since the distribution tool can be used as a tamper. But there’s a reason I continue to use both, and think that it gets better results.
There’s no denying, that preparing espresso in a non-pressurized machine, requires some skill. Not brain surgery skill, but a number of learned processes, nevertheless. One of them is ensuring the ground coffee is distributed and tamped evenly, so that water doesn’t find weaknesses that will cause it to flow through the coffee cracks too quickly. If the flow happens too quickly, it will likely make the coffee sour, since it will be underextracted.
Distribution tools, come in different varieties and work in slightly different ways. Mine is a cloverleaf design, with the circular base split into three sections. Each of these sections has a gradual ramped side, and a stepped side.
If the distribution tool compresses the coffee grounds in the portafilter (and in particular only some of them because of the cloverleaf design), it will create uneven areas of pressure, and avoiding this is the whole point of the distribution tool. So it needs to redistribute, but not compress.
The way I do this with my distribution tool is to place the tool on the portafilter and give a couple of counterclockwise turns, which will scrape the coffee, distributing it into gaps, and creating an even distribution. I follow this with a couple of clockwise turns which will smooth the coffee out. On removing the distribution tool, the grounds will be distributed evenly, but will still be somewhat loose.
And there it is. Follow this process with a tamper, and you’ll have a firm, even pressure applied throughout the portafilter. This results in the water flowing through the coffee at a uniform rate, avoiding that sourness you get from underextraction. I can’t say that I never have leaks in my puck, but they are rare, and I’m never getting sour coffee.
As I mentioned earlier, there are different designs to distribution tools, and I don’t think that one with two split halves, as opposed to cloverleaf designs (with three or four sectors), will have the same problem with uneven compression. Though to be honest, I’m not sure how they’d create any compression at all.