# What to expect from the pre infusion



## AndyZap (Dec 29, 2016)

Hello everyone,

I am about to fit a new pump with a dimmer to control the pressure on my Gaggia, and would love to hear your views on what to expect from the pre infusion / changing pressure profiles with this DIY setup.

Reading the posts on the pre infusion on Gaggia I noticed that people mention "more balanced" taste but with less mouthfeel, i.e. the shots seems more watery. Also the puck is less defined and looks like slurry. A better results were from constant lower pressure (e.g. 8 bar) or a dropping pressure profiles (e.g. 10 -> 3 bar). So is the pre infusion good or bad and what it is for?


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## Mrboots2u (May 10, 2013)

Ignore what your pucks looks like after a shot , it tells you nothing, .taste tells you what you need to know. Low pre infusion may look the puck look different but that isnt really important If you are pre infusing more then grind finer . The noise around watery shots and less mouthfeel is just that, change the grind and brew ratio to obtain a taste you want.... In theory pre infusion allows the puck to expand at low pressure to enable less channelling .

I used flat low pressure 6 bar to great result but you have to have a decent grinder that is good enough and will be consistent enough to get the best results no matter what..( flat pressure or pre infusion )

Personally i would just try a flat pressure profile ( 6 bar ) and one with low pressure 2 bar and then 8-9 bar , dont over complicate it. @MrShades ran a dimmer mod for the gaggia , perhaps he can comment on how effective it is.


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## MrShades (Jul 29, 2009)

I'm also communicating with Andy via email about this, as he seems to be a born fiddler when it comes to his Gaggia...

Anyway, the dimmer mod is really effective at modifying the pressure of the Gaggia extractions - but only when using an Invensys pump. How effective that then is at producing an espresso that you prefer is entirely subjective.

I did quite a lot of playing around, to try and emulate various pressure profiles of lever machines, etc., - and produced lots of "different" shots... but they were all exactly that - different. Better, worse, who knows?

As Bootsy says (and on his suggestion many moons ago) I tried a pretty flat 6 bar extraction and really enjoyed that, probably with and without some reasonable preinfusion. The main challenge, again as mentioned above, and contrary to what you'd think - you need a damn good grinder, as the lower pressure extractions need a much finer grind otherwise they gush. This can then also result in a "slurry" rather than a solid puck, post extraction.

Anyway - it's good fun to play with; whether or not it produces "better" espresso is entirely your opinion.


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## AndyZap (Dec 29, 2016)

@MrShades - I am afraid you are right, at the moment I enjoy my Gaggia mods more than the coffee I make







Hope the next mod will tip it over


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