# Pre infusion



## cavem01 (Oct 3, 2015)

Hi, has anyone mastered the pre infusion on a Silvia without an Auber yet? I have PID'd my machine just not with an over priced Auber!


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## Rhys (Dec 21, 2014)

cavem01 said:


> Hi, has anyone mastered the pre infusion on a Silvia without an Auber yet? I have PID'd my machine just not with an over priced Auber!


I managed it on a Gaggia Classic using the steam knob. Open it up while brewing and it drops the grouphead pressure by venting hot water. Stick a pressure gauge on the grouphead to see when you've opened it enough to drop the pressure to pre-infusion levels, then mark it off with a pen or some black tape so you can do it again. I'm guessing the Sylvia works in the same way as a Classic. Just need to stick a jug under the steam wand and pour back into the tank when done.


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## greymda (Oct 6, 2016)

yes, you have 2 options:

1. steam wand hack

2. mecoffee pid


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## Flying_Vee (May 10, 2016)

Have to say using the steam wand to drop pressure with my classic was small difference and even less so with the Silvia. In fact I've even found it quite negative with the Silvia. Possibly the jump in pressure disrupting the puck which you've lovingly prepared.

I might be talking arse here but would hot water going back in the tank be de-oygenated and therefore poor at extracting second time through the boiler?


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## MediumRoastSteam (Jul 7, 2015)

Flying_Vee said:


> Have to say using the steam wand to drop pressure with my classic was small difference and even less so with the Silvia. In fact I've even found it quite negative with the Silvia. Possibly the jump in pressure disrupting the puck which you've lovingly prepared.
> 
> I might be talking arse here but would hot water going back in the tank be de-oygenated and therefore poor at extracting second time through the boiler?


I can't comment re: de-oxygenation of water... In all honestly. If my chemistry lessons from secondary school serve me well, that's even impossible! 

Pre-infusion: To my experience when I had my Classic, the pre-infusion over the steam wand didn't change anything in the cup taste wise. Also, I found that you are more likely to end up with colder water temp (100ml boiler on the Classic), then having any benefit taste-wise in the cup.

Not sure about the Silvia, as it has a bigger boiler, however a notorious temperature unstable machine.


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## Rhys (Dec 21, 2014)

Well, this shows me opening the steam knob and the pf pressure dropping.






I used to open it up the marks set on the side before turning it on. How this disrupts the 'lovingly prepared puck' I don't know, as the pf is filling at a lower pressure and so will be less disruptive than a blast of full pressure? After 5 seconds or so, I'd just close the steam knob and you'd hear the pressure build up.

For the amount of water you draw off, I seriously doubt it'd make an impact on the oxygen levels in the water.

As I say, I've no idea if the Sylvia works in the same way, I just assumed so.


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## Flying_Vee (May 10, 2016)

Rhys said:


> Well, this shows me opening the steam knob and the pf pressure dropping.


My concern would be that that once the portafilter has filled with water at the nice low pressure then closing the steam wand will create a sudden jump through the already full line to the group from 2 bar as in your video to 10bar (or whatever your machine runs at normally). The classic steam wand is a fairly binary in operation as I remember.

Where as not opening the steam wand means that although the system is going to rise to 10bar, that this happens a little more gradually as the water is delivered through the group and wets out the coffee before full pressure is achieved.

I'm filling this under my bullshit theory category as I dont really know much about these machines but I enjoy thinking about the physics.

It would be good to see a video to replicate how you would actually use the steam wand in pre infusion rather than the reverse.


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## Flying_Vee (May 10, 2016)

MediumRoastSteam said:


> I can't comment re: de-oxygenation of water... In all honestly. If my chemistry lessons from secondary school serve me well, that's even impossible!
> 
> .


Ha ha. I was thinking more about the importance of O2 gas in the water, rather than water splitting. Like aeration of wort for fermentation or the reason you would never twice boil a kettle to brew tea. Similarly I'd worry that water that had been through the boiler may not be as good second time round. But I'm not sure on the importance of O2 in coffee extraction.

Anyone? Surely those water boffins on the other threads would have an idea


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## Plasse (Apr 9, 2017)

Without commendering the thread - which would be the best lid solutions for a gaggia baby/Silvia? Thinking about upgrading or 'upgrading'


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