The Espresso Unplugged team has developed a technique for increasing the pressure with your ROK espresso maker. This allows you to get the best espresso possible from your machine! It also works on the Presso, but be forewarned: The plunger on the Presso is not as robust, and care should be taken not to break your plunger!
Begin with the normal procedure of preheating your cylinder and use your normal grind in the portafilter. Once you're ready to fill the cylinder for pulling your shot, the difference begins!
Fill the cylinder almost to the top with hot water. Now wiggle the handles up and down just enough to release the air under the plunger. Do this until all the bubbles have stopped and the water level doesn't go down any further. Now fill your cylinder the rest of the way up with more hot water and gently raise the arms to the top.
When you press down on the arms, the first thing you'll notice is how difficult they are to press! This is because water is essentially incompressible, whereas air is readily compressed. That means all your energy is pushing the water through the grounds instead of some of it being wasted compressing air trapped under the plunger!
Watch the espresso carefully as you extract it from the beans – with all this extra water in the cylinder, it's easy to draw too light a shot. But if you pay attention to the color, you will get a cup of the best espresso possible from your ROK!
Give this method a try and let us know what you think! Did it work for you? Did you run into problems? Let us know!