I have a rancilio silvia, and rocky grinder for two weeks. My espresso is delicious, nice thick crema, etc. Here is my question, folowing the golden rule on a double or single shot, my extracted espresso comes out of the portafilter dark brown for only 10 seconds then turns the colar of dark honey and continues to lighten. The extraction time is between 20-20 secs. Should my extracted brew be dark brown from beginning to end? I have changes tamp pressure and grind. Now grind is set to 8.