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  • static pre-infusion

    Can anyone explain what this means, and how it works?

  • #2
    Re: static pre-infusion

    Preinfusion is one of those irritating terms that everyone seems to use differently. I think that static preinfusion basically means that the water is allowed to saturate the coffee bed at line pressure, without the pump running. For this, the machine must be plumbed in.

    As for how it works, I guess that a better question is whether it works. Legions of people out there seem to be of the impression that preinfusion is a good thing. Im not so sure. Some of the best shots that I have had have started pouring three seconds after the pump was engaged. Many say that apparently it is more difficult to pull consistent shots without some sort of preinfusion.

    Then we get into the question of whether line pressure preinfusion itself is a good thing, as opposed to any other type of preinfusion. Many machines use a gicleur/restrictor to slow the build up of pressure with the pump running. Some people insist that this is not preinfusion. Regardless, we have an easy way to compare the two in the Synesso Cyncra. This machine has both a gicleur and a three position paddle. The paddle has an off position, a middle position that allows water to flow at line pressure without engaging the pump and an on position. The idea is that the middle preinfusion position allows you to control the length of the preinfusion time. The fact is that I have never seen anyone actually use the middle position; in cafes, the lever always goes fully on and the gicleur takes care of the pressure build up. Perhaps the middle position would be more useful if there were no gicleur.

    Hope that helps,

    Luca

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    • #3
      Re: static pre-infusion

      Originally posted by luca link=1231326917/0#1 date=1231329488
      Preinfusion is one of those irritating terms that everyone seems to use differently.  I think that static preinfusion basically means that the water is allowed to saturate the coffee bed at line pressure, without the pump running.  For this, the machine must be plumbed in.
      Yeah thats pretty much my understanding of static pre-infusion.

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      • #4
        Re: static pre-infusion

        Good summary of pre-infusion! The only thing Id not agree with is to define it as at "line pressure". While thats often the case, I think its more the case of being at "lower than brewing pressure". This would capture various types of restrictors placed in line. What it is certainly debatable is whether an electronic system that pulses the pump on, off for a pause, then on to brew is "pre-infusion". While manufacturers may claim it is, I would suggest not, as all it does is slam the puck briefly with brew water, then waiting for it to swell before slamming it again.

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        • #5
          Re: static pre-infusion

          would some palate pros like to discuss their views on how preinfusion GENERALLY affects the taste of the shot? luca, i think you talk about long preinfusion muddying flavours, while shorter dwell time (i guess not exactly the same thing as less preinfusion) reveals more nuances?

          in the S1cafe, the spaziale forum for vivaldi owners, (where some have optioned up to programmable preinfusion which is adjustable for length of pi time) they talk a little bit about length of preinfusion and its effects - not so much in the cup, though. seems a lot of preinfusion talk is theoretical rather than real life in terms of end product.

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          • #6
            Re: static pre-infusion

            Hi Aaron,

            I think that theres a fair bit of evidence that preinfusion makes your shots less likely to channel and, so, most commercial machines are fitted with gicleurs. Off the top of my head, I cant think of any commercial machine that would ship stock without gicleurs of some description, so I think that most people would only have experience with machines with gicleurs in them. Josephs Mistral arrived without gicleurs in it and I thought that it was pulling beautiful shots. Surprisingly, they were tasty without sacrificing body, though that might have been something to do with the blend. Joseph did end up fitting standard gicleurs to the Mistral; presumably he wanted to keep his machines consistent across the shops, which is a clever idea. I cant remember too much of our experiments with the middle position of the synesso lever at the maling room, but we certainly didnt think that the middle position was worth the hassle. Anecdotally, I can say that I think that machines that take too long to get to first drips usually lead to less clear shots than machines with a faster pressure rampup. Often, the shot seems to speed up towards the end. This is obviously an area where some research would be fruitful.

            Cheers,

            Luca

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            • #7
              Re: static pre-infusion

              as all it does is slam the puck briefly with brew water, then waiting for it to swell before slamming it again.
              I have been in contact with a supplier of PIDs for the Silvia who have added a preinfusion function, at the time I was tossing up to go that way or not, anyways, with their method the 3 way valve is open during the pulse and soak time and closes when the shot itself starts, I suppose it avoids the double slam effect, they did say it was also easier for them to implement.

              Following on from Lucas comments maybe with a vibe pump and gicleur we dont need the preinfusion chamber of the lever E61s, the solenoid operated type as fitted to models like the Diadema Junior or Expobar Pulsar may be sufficient. Just a thought, I would love to hear opinions.

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              • #8
                Re: static pre-infusion

                I agree pre-infusion seems to be one of those things where it is hard to get a detailed description of how things work. In terms of static pre-infusion, here is a description I found on ECM website today. For some reason the text wouldnt copy, so here is a pic.

                I did also see someone refering to static pre-infusion as mains pressure infusion like you say Luca.

                I was trying to find a name for the type of pre-infusion my pavoni pub has, but I dont think this is it!




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                • #9
                  Re: static pre-infusion

                  Have just started with manual static pre-infusion techniques (i.e. flicking the switch on/off) on my Silvia. Was having trouble with little squirters from the naked p/f and an average-subpar shot coming out. First one out was a spectacular looking shot, tiger stiped and pouring like honey. Tasted great too! This is using a Sunbeam EM0480 grinder, and my instinct is telling me that the preinfusion (albeit a bit of a rough one) gives a lot more room for error due to swelling the puck inside the p/f. Ill be getting a Mazzer next week, and I intend to do a few more tests to see what I can find. Unfortunately, I cant be sure at this stage if the preinfusion had much to do with it as Im using different beans, stirring the grinds more in the portafilter for even distribution, tamping better and levelling differently. Looking forward to figuring out how to get the best shot from the new setup soon ;D

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