This is a demonstration of what an espresso shot from a ROK, looks like when your coffee is ground too coarse. Coarse coffee creates less of a barrier to the water and so doesn’t allow you to build enough pressure for good extraction. The water flows too fast and the resulting coffee will lack crema and taste weak / bitter.
What Should it Look Like?
This is what a shot will look like when you find the correct grind.
Remember there are a few other factors: fresh coffee (<14 days), fresh ground (no preground). We’ll post more about these soon.