After reading Scott Rao's book and the info about preinfusion, I started running a little bit of water from the brew head onto the tamped coffee before locking in the portafilter. I thought this would be similar to what a more expensive machine would do but without any pressure (I own a *$ Barista machine). It sure seemed to decrease the number of gushers I had when I was grinding with my Kitchenaide grinder. I've since upgraded to a Mazzer Major and most of my problems with inconsistency problems are gone. I still do the "manual" preinfusion out of habit. Maybe tomorrow I will try to compare with and without the technique and report back.

Any thoughts on whether this technique is accomplishing anything close to the preinfusion you get on higher end machines?

Michael

one lump or two? wrote:Any thoughts on whether this technique is accomplishing anything close to the preinfusion you get on higher end machines?

No, it isn't close. Higher end machines apply the preinfusion water under (reduced) pressure. It is unlikely that the water you are dripping on the puck is penetrating more than 1 or 2 mm.

There is a good chance that if you tried that with a non pressurized portafilter, you would get ugly shots. Just poring water on top of the puck is more likely to disturb the top layers of the puck and cause channeling. As Marshall points out, you are not getting enough penetration of the water to do any real preinfusion. Normal preinfusion applies water at low pressure for an even distribution of water across the puck. The low pressure also pushes the water through the puck given enough time. The entire puck is wetted before the pump kick on but not so long as to get drops out of the basket before the pump kicks in.