Pre-infusion on silvia

[Kristi]

I've read a lot of posts here and on cg (mostly the E61 stuff) but have not found the answers.
I understand that the intent is to wet the grounds at normal pressure before hitting them with 9bar.

1. What change in taste results from preinfusion?

2. How would simulate preinfusion on the Silvia? :

2a. How long would I initially flip the brew switch on and off? 1 sec, 2 secs, ???

2b. How long would I wait before pulling the shot?

tia
Kristi (moose and squirrel)(Rocky and Silvia)

[cannonfodder]

Preinfusion allows the grounds to bloom prior to the extraction. I think I get a much richer and fuller cup, I also think I get a better crema but that may just be me.

Preinfusion on a Silvia would have to be 'pulse' preinfusion, like the LM GS3. You simulate preinfusion by turning on the pump for a few seconds, then off for a couple and then back on for your extraction. As to the timing, not sure, you would have to experiment. You want enough water to saturate the puck, but not enough to flow liquid out of the basket. If I had to guess, I would say start with 3 seconds on, two off and then go, but I have never owned a Silvia so take it with a grain of salt.

[Kristi]

Thanks! Much appreciated!

[malachi]

If you're using pulse preinfusion, keep in mind that the values (on and off) are going to be different for a rotary pump vs a stock vibe pump. In addition, they will vary from machine to machine based on flow rate, etc.

That being said... with the GS3 I've found the best results with a 0.9second on/2.4second off timing.

The returns from preinfusion will also depend in part upon your coffee selection.

[Kristi]

If you're using pulse preinfusion, keep in mind that the values (on and off) are going to be different for a rotary pump vs a stock vibe pump. In addition, they will vary from machine to machine based on flow rate, etc.

That being said... with the GS3 I've found the best results with a 0.9second on/2.4second off timing.

The returns from preinfusion will also depend in part upon your coffee selection.

Interesting...

I tried the 3 sec on, 2 sec off then go, this morning, and got a good coffee tasting cup, where I normally get a sweeter chocolaty cup (Caffe Fresco Ambrosia). I can't achieve your accuracy, but I will try your suggestion.
Thanks!
Kristi

[Jerome a Nantes]

The preinfusion, in the reference system E61, is a chamber on the circuit of extraction water, the pressure increases when the chamber is full.

You can probably simulate the same effect with the hot water knob :
Activate the brew switch with the hot water knob open : the pressure does not increase in PF.
After a volume of water out (to be defined), close the knob.
Extraction can finished normally.

I have made some encouraging tests but it seem to be necessary to use a more scientific way to try it.
There is some parameters :
- degree of open hot water knob (hard to control)
- volume of water out


Post Scriptum :
I'm sorry, I haven't written a post to introduce myself, it is coming soon!
I want in first understand how to ask for a LMWDP number for the european branch (France in fact)

[Kristi]

Thanks Jerome - just played with that a little without coffee and devilishly hard to control precise opening of knob.

Does not the regular brew-on start out with 1bar and build up over 2-3 sec to 9bar, which might mean that it's already getting a sec or 2 of ""pre-infusion"" (massive quotes)?

I just tried 1sec on, 2.5sec off, and go. The cup was "clearer" (only word I could come up with) than the previous attempt, but again the flavors were missing (again, nice coffee taste, though). I think that I have lowered my boiler 1 or 2 degrees F too much, so the jury is still WAY out on this approach and these timings. Gotta get that rope heater... Everything is Andy's fault! ;o)

Jerome, if you get any more specifics on this, please post them so I can give them a try!

Kristi

[Dogshot]

By pulsing the pump, it will engage the solenoid. I don't know what effect that would have on a damp puck, but it might not be pretty (does anyone know?). By opening the steam valve to mimic preinfusion, it greatly complicates the whole temperature management process.

After trying to get reasonable results using both methods, I concluded that I could not improve my shots by attempting preinfusion on my Gaggia. I look forward to hearing about your findings.

[Kristi]

By pulsing the pump, it will engage the solenoid. I don't know what effect that would have on a damp puck, but it might not be pretty (does anyone know?). By opening the steam valve to mimic preinfusion, it greatly complicates the whole temperature management process.

After trying to get reasonable results using both methods, I concluded that I could not improve my shots by attempting preinfusion on my Gaggia. I look forward to hearing about your findings.

Ahhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh

That probably explains what looked like channeling on the top 1/4 of the thickness of the puck in a couple of places with my second attempt - top of puck looked very rough. I dried it out and examined it carefully and none of the channeling went through, but i bet you're right. the 3-way solenoid releasing the pressure is sure gonna do something!

THANKS!!!!!!!

I, uh, think I'll forget about preinfusion!
Kristi

[mrgnomer]

top of puck looked very rough

Could be the polish as well. I used to get a rough looking top on the puck before I started finishing with a tamper weight polish.

The pre infusion with the Silvia is a great question. I think my Silvia's brew pressure is high (haven't measured it yet, though) and I was getting a lot of channeling at the start. My thinking is that the Silvia's pressure slams into the puck right from the get go and if the puck isn't just right to resist the pressure uneven extraction happens right away.

Encouraging the puck to bloom and tighten up in the basket seems to be the way to go. I found that the water pressure is pretty low when the steam knob is open with the brew switch on. You can see it with the pf off. Closing off the steam knob ups the pressure.

With this in mind I've gotten my best pulls so far by just cracking open the steam knob before hitting the target temp at the top of the boiler (top of the boiler temp monitored with temp meter and thermocouple attached to the top of the boiler), switching on the brew switch and slowly closing the knob over about 3 sec to initiate the pull.

If the grind, dose, distribution and tamp were all good, the pull is consistently good. I do think infusing the puck with brew water at low pressure for a few seconds then increasing the pressure for espresso extraction makes a big difference with the Silvia. If know the temp of the water out of the boiler I don't think it makes a big difference in extraction water temp to extend the pull a few seconds by having the steam knob open. Bleeding steam and a bit of water off the top of the boiler by opening up the steam knob does drop boiler temp but not that fast and if the brew group is heated up to atleast 180F the temp stays stable. I haven't had a problem with sour pulls as a result of opening up the steam knob just before the pull.

I haven't tried the pulse infusion method.

Pressure moding the Silvia seems to be a popular solution as well to her high pump pressure.
http://mysite.wanadoo-members.co....iaPressureMod.html