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Thread: To Expand or Not to Expand...THAT is the Question !

  1. #1
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    To Expand or Not to Expand...THAT is the Question !

    Gene Cafe Coffee Roaster $850 - Free Beans Free Freight
    Well so as not to over run a another Thread ....here...
    https://coffeesnobs.com.au/brewing-e...er-bep920.html

    I thought I'd start another and throw it open to CS'ers' to further chew over...

    Specifically around post #33...see of the thread above... and see here
    Post #33
    Date 17/3/2019
    "Contrary to popular belief the puck does not expand when saturated with water. The screen imprint comes when the shot is stopped and the pressure is relieved when the 3-way valve opens which results in a negative pressure in the portafilter sucking the puck up against the screen.
    Have a read/view of the Clear naked portafilter thread from 5 years ago.
    Java "Clear view" phile|


    The facts around Coffee Puck Saturation / Expansion during the Espresso Shot process.
    And the phenomena I refer the 'The Stuck Puck' or Sucked Puck syndrome raised its ugly head...again.
    No no no...JP there is no specific relationship to you meant at this point !

    And yes I still do occasionally experience this - with a single basket, Synesso 7-9g which I unashamedly overdose at 10.something,grams. And do pull a lovely shot that blends ...so my Better half says....with around 165g stretched milk ...and she just luvs me for it...no I mean she enjoys it always !

    So I'd basically given up n trying to understand this not often repeated phenomene'n and put it down to when the gods align on just the right (wrong) amount of clearance between the S/Screen and my puck.....YES thats right folks I only ever overdose one of my baskets (in comparison to the oem stated range) BUT still abide by the CS rule of never being in contact with the S/Screen!.
    For fear if my mother found out ...Oh she be so ashamed!

    NOW keep following


    https://coffeesnobs.com.au/brewing-e...rtafilter.html

    and the following post ..... Dated 30/6/2014
    "With the puck not expanding until after the extraction is over unless you are over filling your basket the puck does indeed always have a "free surface". The only time this isn't the case is when you smash the puck into the shower screen when locking the portafilter on. In which case you're over filling the basket.
    Java "More Science!" phile
    [QUOTE=Javaphile;648113]
    So sorry JP...Now Im going to engage you JP in a battle of Wits ! .......
    In which you referred to the above thread and has stated the Puck does not expand.
    Rather it is sucked up into the S/Screen during the vacuum effect just prior to first water flow.
    Which this video does not concur with your inference
    So as a way of helping us all understand better the magic that takes place in the GH
    during a pour I accept ....
    1/ There is a Vacuum / Suction effect that can take place and suck the puck up into the S/Screen, on occasions.
    In my own experience - I would right here and now Accept / offer that this occurs and given the 'right' weight of grinds, the right 'gap'
    for the puck to lift and yes bingo this does occur. But does it always? And in difference to Puck Saturation / Expansion.
    Now in the video shown in the old thread above ....I question ...
    The extremely low does weight that is used as an example and therefore using this as the one and only way a Showerscreen can and does imprint itself upon a coffee cake post shot.

    And offer my own experiences of setting up varying (12 or more) different baskets and my own rules I've come to accept work for me, and repeatedly use, and do so ongoing with consistently.
    Being -
    In the initial stages set the puck inside the depth / clearnace of te 5cents and et the puck expand into the screen so as to provide maximum resistance against the flow of the machine. Adjust Grind. Confirm Grind Setting. Then from then on I can finely retune my dose weight down, my puck height lower and my grind finer so as to allow more 'head height' so the puck will no longer contaminate the above the S/Screen and therefore initiate excessive cleaning etc.
    This also provides a finer grind setting which (right or wrong?) i think provides more consistency in the setup as the grinder is doing the work(I tamp lighter also). The puck finishes more saturated and has a soft pillow like effect on top...(which mean f'all I s'pose!

    So Does the Puck Expand or Not?
    I'm yet to be convinced that it doesn't !
    Dose the Puck always get Sucked up into the ShowerScreen??
    My response is - How can it when you have say a Triple Basket dosing at 23g... its toooo heavy. I say not always.
    So why can I illicit a S/Screen imprint on such a heavy puck then?

    And Javaphile ...Why did you edit said thread - Clear PortaHandle...above
    on the afternoon of the 17th March 2019 ???? The plot thickens !

  2. #2
    Super Moderator Javaphile's Avatar
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    Quote Originally Posted by EspressoAdventurer View Post
    And Javaphile ...Why did you edit said thread - Clear PortaHandle...above
    on the afternoon of the 17th March 2019 ???? The plot thickens !
    Let's deal with this first so-as to clear the air of any thoughts of my having changed/manipulated a post to bolster my position/argument.

    In the edited post if you click on "Last edited by Javaphile" you will be taken to a history of all changes made to the post. There you will see that the only difference from the original post to the one you see now is the formatting of the video link. The old format no longer worked (No link nor video appeared in the post.) so I changed the formatting of the video link so that people could see the video. If you need further proof scroll down through the thread and you will see where some people, notably those using an ipad, could not see a video in the original post. In post #9 you will see where another user posted the video link using a different format so everyone could view it. Note that it is the identical video link that appears in the now 'fixed'/edited post.

    Now onto the expansion issue.

    Quote Originally Posted by EspressoAdventurer View Post
    Well so as not to over run a another Thread ....here...
    https://coffeesnobs.com.au/brewing-e...er-bep920.html

    I thought I'd start another and throw it open to CS'ers' to further chew over...

    Specifically around post #33...see of the thread above... and see here
    Post #33
    Date 17/3/2019
    "Contrary to popular belief the puck does not expand when saturated with water. The screen imprint comes when the shot is stopped and the pressure is relieved when the 3-way valve opens which results in a negative pressure in the portafilter sucking the puck up against the screen.
    Have a read/view of the Clear naked portafilter thread from 5 years ago.
    Java "Clear view" phile|

    ...NOW keep following


    https://coffeesnobs.com.au/brewing-e...rtafilter.html

    and the following post ..... Dated 30/6/2014
    "With the puck not expanding until after the extraction is over unless you are over filling your basket the puck does indeed always have a "free surface". The only time this isn't the case is when you smash the puck into the shower screen when locking the portafilter on. In which case you're over filling the basket.
    Java "More Science!" phile

    So sorry JP...Now Im going to engage you JP in a battle of Wits ! .......
    In which you referred to the above thread and has stated the Puck does not expand.
    Rather it is sucked up into the S/Screen during the vacuum effect just prior to first water flow.
    Which this video does not concur with your inference
    So as a way of helping us all understand better the magic that takes place in the GH
    during a pour I accept ....
    You have misquoted/misattributed me twice. I never said "...the Puck does not expand." What I did say was "Contrary to popular belief the puck does not expand when saturated with water." and "With the puck not expanding until after the extraction is over" (Note, the bolding was yours, not mine.)

    Your other misquote/misattribution is "Rather it is sucked up into the S/Screen during the vacuum effect just prior to first water flow.
    Which this video does not concur with your inference". What I said, in addition to the above 2 quotes, was "The screen imprint comes when the shot is stopped and the pressure is relieved when the 3-way valve opens which results in a negative pressure in the portafilter sucking the puck up against the screen." (Note bolding added by me.)

    Quote Originally Posted by EspressoAdventurer View Post
    1/ There is a Vacuum / Suction effect that can take place and suck the puck up into the S/Screen, on occasions.
    In my own experience - I would right here and now Accept / offer that this occurs and given the 'right' weight of grinds, the right 'gap'
    for the puck to lift and yes bingo this does occur. But does it always? And in difference to Puck Saturation / Expansion.
    Now in the video shown in the old thread above ....I question ...
    The extremely low does weight that is used as an example and therefore using this as the one and only way a Showerscreen can and does imprint itself upon a coffee cake post shot.

    And offer my own experiences of setting up varying (12 or more) different baskets and my own rules I've come to accept work for me, and repeatedly use, and do so ongoing with consistently.
    Being -
    In the initial stages set the puck inside the depth / clearnace of te 5cents and et the puck expand into the screen so as to provide maximum resistance against the flow of the machine. Adjust Grind. Confirm Grind Setting. Then from then on I can finely retune my dose weight down, my puck height lower and my grind finer so as to allow more 'head height' so the puck will no longer contaminate the above the S/Screen and therefore initiate excessive cleaning etc.
    This also provides a finer grind setting which (right or wrong?) i think provides more consistency in the setup as the grinder is doing the work(I tamp lighter also). The puck finishes more saturated and has a soft pillow like effect on top...(which mean f'all I s'pose!

    So Does the Puck Expand or Not?
    I'm yet to be convinced that it doesn't !
    Dose the Puck always get Sucked up into the ShowerScreen??
    My response is - How can it when you have say a Triple Basket dosing at 23g... its toooo heavy. I say not always.
    So why can I illicit a S/Screen imprint on such a heavy puck then?
    Did you watch the video referred and linked to in post #24 in the Clear naked portafilter thread? In shot after shot it clearly shows that the puck does not expand until the shot is stopped and the pressure is relieved.

    Now as to the sucking/expansion question there are several issues to be addressed. Depending on the machine being used the puck's behavior will be different.

    The machine being used in the long (9:24) video releases the pressure very gradually when the 3-way valve is opened at the end of the shot to relieve the pressure. With a gradual relieving of the pressure the best description of the puck's behavior is that it expands, by quite a bit as shown in that video, which it can do as it has a huge overhead. If it had been dosed to the proper level (i.e. Very close to but not touching the screen.) it would clearly have expanded into the screen.

    When used on a machine where there is a near instant reduction of the pressure when the 3-way valve relieves the pressure at the end of the shot the entire puck is sucked upward into the screen before it has a chance to expand. (There used to be several other videos using a different machine where this effect was shown but I no longer seem then linked/shown on Vimeo. As I recall they were done by the person who did the first, shorter, video in the Clear naked portafilter thread.)

    No matter which machine is used and whether it is via just expansion (A slow reduction of the pressure.), or sucking (A very rapid reduction of the pressure.), or a combination of the two the screen imprint does occur but not until after the shot has ended.

    As to your argument that the puck is too heavy to be sucked, up a few grams difference in weight means absolutely nothing when dealing with 9 or 10 bars of pressure.

    Now, there is a scenario where the above behavior will be different as the forces involved are different. This would be on a machine where there is no 3-way valve or other mechanism to relieve the pressure at the end of the shot. On those machines you have to wait for the pressure to be relieved via exhausting through the puck. (If you don't wait and force the portafilter off you will have a quite powerful explosion sending scalding water/steam and coffee grounds all over you and your kitchen.) I suspect on one of these systems you may see a slight expansion of the puck. How much will depend on how fast the pressure is relieved through the puck. On some machines you may even see a sucking action if the pressure relieves quickly enough and the brewing head cools off enough to create a negative pressure differential between the inside of the grouphead and the outside atmosphere. On other machines there may be no expansion nor sucking behavior displayed as the puck may dry out as the pressure is relieved making it too dry to expand.


    Java "Did I miss anything?" phile
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  3. #3
    Mal Dimal's Avatar
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    Behmor Brazen - $249 - Free Freight
    Java "Did I miss anything?" phile
    If you did mate, I sure as hell can't see it...

    Mal.
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