# Pre-infusion on a Classic?



## Rhys (Dec 21, 2014)

Read a few things about pseudo pre-infusion on a Classic and wondered if it actually works?

Opening the steam valve slightly to reduce group-head pressure for about 5 seconds then shutting off for the duration of the shot.

Tried it a few times and am wondering if it does work, seam to get a nice tasting shot from it but that might be me getting better at 'pulling' them. Read about switching to steam mode for 5 or 10 seconds, switching back then opening steam wand before starting as well.

Has anyone done a portafilter pressure test whilst opening the steam valve? If not I might have to connect my gauge again that I bought to do my OPV and have a look. Thought I'd ask first in case it was a waste of time.


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## hotmetal (Oct 31, 2013)

I don't know about that method but my old classic had the auber PID and that had a "PI" function that basically turned the pump on briefly (configurable but roughly 1 second IIRC) which puts a small amount of water onto the puck but stops before any pressure builds up above it. Then it waits ("dwell time") which was maybe 2.5 seconds as standard; after this the pump kicked in for whatever you set the shot timer to. This seemed to give me good results and would be fairly easy to replicate roughly just by flicking the pump switch on/off/on manually. Dunno, worth a try?


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## froggystyle (Oct 30, 2013)

I read about it, but never tried it. Earwax said he tasted an improvement on Twitter.... If you have gauge then do some testing on how far you need to open the valve to keep it at say 1 or 2 bar, then pull some shots and taste...


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## Rhys (Dec 21, 2014)

When I open the steam tap the pump doesn't labour but I'm not opening it all the way, just letting a trickle out. The last one I did I opened it for 10 seconds then slowly closed it - I heard the pump change as pressure built up.

Was 18g in, 32g out in 30 seconds total (inc. 10 seconds with steam valve open). Used supermarket bought Taylors of Harrogate beans for a change and produced a nice shot - had as a flat white and wasn't bitter, slightly sweet in fact (herself approved).

I was going to try a ramp down by very slightly opening at the end to drop the pressure slightly (been watching youtube vids of Vesuvius machines) but thought it might affect the solenoid when I shut it off and end up with a soggy puck. The puck was nicely dry btw with no cracks/venting etc.

Trouble is when trying these things out you can only do it a few times as otherwise I won't sleep lol


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## froggystyle (Oct 30, 2013)

It's Friday. Why do you need sleep?


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## Rhys (Dec 21, 2014)

froggystyle said:


> It's Friday. Why do you need sleep?


Had three double shots this afternoon/evening..


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## Mrboots2u (May 10, 2013)

Rhys said:


> Had three double shots this afternoon/evening..


Lightweight


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## Rhys (Dec 21, 2014)




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## hotmetal (Oct 31, 2013)

Don't forget Cornholio from Beavis and Butthead!


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## Rhys (Dec 21, 2014)

hotmetal said:


> Don't forget Cornholio from Beavis and Butthead!


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## Neill (Jun 26, 2013)

hotmetal said:


> Don't forget Cornholio from Beavis and Butthead!


I need TP for my bunghole.


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## Mrboots2u (May 10, 2013)

This isn't Yemeni.....


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## hotmetal (Oct 31, 2013)

He. Hehe. He hehe hehe. He said bunghole. I am the great Cornholio!


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## Mrboots2u (May 10, 2013)

Neill said:


> I need TP for my bunghole.


Yeah Colin mentioned you had the condition


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## Rhys (Dec 21, 2014)

I think I'll set up my pressure gauge tomorrow and try it.

Would any other PID do the pre-infusion? Like for eg the REX C-100 on fleabay?


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## froggystyle (Oct 30, 2013)

You could read up on the dimmer switch mod...

http://coffeeforums.co.uk/showthread.php?20477-Gaggia-Preinfusion-Dimmer-amp-Panel-mount-Guage-mod


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