# Pre wetting



## Eyedee (Sep 13, 2010)

I know there are not too many Piccino owners on the forum but this observation will apply to numerous other machines.

As an experiment I tried pre-wetting the grinds. Locked in the PF, pressed the start button, counted to 3 and stopped the shot. This discharged a small amount of water into the PF without any build up of back pressure.

Counted to 3 again and restarted pulling the shot up to it's normal extraction.

I found the finished product to have a little more body to it and watching the naked PF the shot appeared to maintain additional intensity of colour throughout the pull.

As we know water always finds the easiest route so will this technique help the flow through the grinds ?

As i don't drink espresso my appreciation might be a little skewed but I wondered if this was similar to an automatic pre-infusion which the more expensive machines perform automatically.

Ian


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## Kyle548 (Jan 24, 2013)

I'm not sure if PI like this works.

There's nothing stopping the machine ramping up the pressure - even after 3 seconds, the pressure will be high.

Killing the shot will engage the solenoid, which will create back pressure and suck the puck up against the screen - probably fracturing it.

Next time you do this, after you turn the pump off, take the PF out of the group and check the puck - if it has the shower screen on it, then it is being sucked up.

I suppose if the pressure only ramps up to something like 1 bar, then the back pressure wouldn't be enough to fracture the puck, but its difficult to know how high the pressure actually is.

Expensive machines basically dribble water at a low pressure and then brew all in the same cycle without tripping the solenoid. E61 actually has the solenoid and PI as opposite positions on a mechanical switch which manually opens the group.


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## shrink (Nov 12, 2012)

I would think that until the PF fills up totally with water and the water itself starts to push against the shower screen as back pressure, that in reality the pressure inside the PF is very low.

I'd suggest that for the first 3 seconds its more of an unpressurised "shower" if water that occurs. Whether its a substitute for real pre-infusion... i don't really know!


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## Mrboots2u (May 10, 2013)

Pre infusion the e61,version

What is Pre-Infusion?:


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## Mrboots2u (May 10, 2013)

Mrboots2u said:


> Pre infusion the e61,version
> 
> What is Pre-Infusion?
> 
> :


Bill crossland used to work in some capacity for La marzocco I think.


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