Pre-Infusion, longer vs. shorter? - Page 3

#21: Post by **timo888** » October 13th, 2009, 2:38 pm

F.M. wrote:The vivace beans "feel" different at the lever, compared to the commercial beans I sometimes use. When using the vivace beans, the lever feels ... like it's pushing back up) and I don't get any espresso until the lever is more than half way through the pull. ... With the commercial beans set to an equally fine grind, there's none of the spongy feel, the machine just either chokes up or I get drips or drizzle 1/4 of the way into the pull.

Also- today, after locking the PF in, I had a momentary distraction resulting in a longer than regular pre-infusion (probably :20)... this resulted in the machine being almost locked up at the very top of the lever stroke. It was as if the puck had swollen to the point of not letting water pass or enter the group head. With a little coaxing things started flowing nicely, the machine was not choked up. Just over pre-infused, like. Interesting!

No, "not over pre-infused, like". It is impossible to over-saturate.

When the extraction chokes as you describe, IMO this should not be blamed on preinfusion but to a combination of variables, primarily dose, grind, compaction. Your basket was possibly overdosed, or you tamped too heavily given the fineness of the grind, or you ground too finely given the tamp force you used.

Now, you may not want to saturate the puck before you begin the extraction, and prefer to "partly preinfuse" and leave some of the coffee dry and still capable of absorbing water, so that the coffee would continue to swell during the extraction proper and your shot volume would be less. That's up to you.