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wet/sloppy puck and preinfusion questions...

Posted: Sat Aug 07, 2010 2:17 pm
by cloudcover
hi there -

i recently bought the vivaldi ii along with a baratza vario grinder and previously had an e61 heat exchanger machine. with my previous machine, i used to examine the puck after pulling a shot to help diagnose my technique. looking at the puck would help me notice holes that might be causing channeling, etc.

i'm finding that on the vivaldi ii that the puck is often too wet or sloppy to knock out intact. i've tried changing grind settings and dose amounts. in terms of dosing, it's typically right at the indented line of the portafilter basket after tamping (usually about 16g by weight). it seems that the problem is more pronounced when i grind finer and the shot takes longer to extract (say, like 35 seconds). and but on my e61, even those kinds of shots would result in a puck that could easily be knocked out.

any suggestions/thoughts on what's going on? is it normal or does it indicate some problem either in my technique or the machine's operation? if there's some issue with the machine, then i'd want to make sure i had it addressed while it was still relatively new.

oh, and one other question, about preinfusion. i noticed a couple of suggestions to pre-infuse for 6 seconds and was wondering if that was a common setting as a default. also, i don't have a good way to measure pressure on my water line (the plumber put in a restrictor but it doesn't have a gauge or anything), and was wondering if there's another way to calibrate that. for example, if i knew that a 6-second preinfusion at xxx psi/bar yields 3 ounces of water, then i could adjust my restrictor to get the same amount of water in 6 seconds.

thanks,
cc

Re: wet/sloppy puck and preinfusion questions...

Posted: Sat Aug 07, 2010 3:30 pm
by slo
Hello and welcome.

A sloppy wet puck is a normal event with the Vivaldi. There has been many theory put forth on this but nothing definitive (that I know off). But it is nothing to prevent a good shot for sure.

I pre-infuse for the whole 8 seconds with a 28 PSI regulated dynamic pressure (30 PSI static). This is the setting I found the most appropriate to my taste preference and methods.

Re: wet/sloppy puck and preinfusion questions...

Posted: Sat Aug 07, 2010 7:52 pm
by Endo
I get quite a few wet pucks as well.

I find they get wetter if you grind fine for a ristretto and use very fresh coffee (both good things of course). The Vario also seems to be worse than my Mazzer (perhaps due to more fines that plug the grounds).

It must have something to do with either the dispersion screen or more likely, the extra deep puck. I'm have a theory that the taller Vivaldi pucks require a harder tamp (and nutation) to get a good pour. The top layers get compressed harder thanh an E-61, but the lower layers less. This makes it hardrer for water to penetrate the top. Just a theory of course.

In any case, you'll need to get used to it. If it makes you feel better, I don't think it makes much of a difference in the cup.