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Thread: Remnant coffee on shower screen

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    Junior Member Kanga1788's Avatar
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    Remnant coffee on shower screen

    Gene Cafe Coffee Roaster $850 - Free Beans Free Freight
    Hi. I was wondering if I'm filling my basket too high because I always have lots of coffee stuck to the shower head after pulling a shot. Is this normal? I have an expobar office. It is easy to remove when the machine cools down however more difficult when still warm and you want to brew another shot! Any tips would be appreciated!

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    Senior Member speleomike's Avatar
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    Hi

    I always have a bit of coffee left on the screen on my machines. If I am pulling another shot i don't worry about it as its very little. If it was a fair bit then all you need to do is to put in the PF and pull the handle for a few seconds, wobble the PF a bit to loosen stuff under the seal. Then remove, ditch any water and coffee in the basket, and load your next shot.

    After the machine has cooled I always use a brush to clean the underside of the scree and run my finger or a cotton bud around the outside of the screen and where the seal goes.

    Mike

  3. #3
    TOK
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    Quote Originally Posted by Kanga1788 View Post
    Hi. I was wondering if I'm filling my basket too high because I always have lots of coffee stuck to the shower head after pulling a shot. Is this normal?..........Any tips would be appreciated!
    No not normal for a properly dosed, ground and tamped puck.

    Contrary to your proposition, on the limited information supplied, I would surmise that you are UNDER dosing.

    Hope that helps.

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    Senior Member GrahamK's Avatar
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    I assume you are removing the PF immediately after pulling the shot. I usually only get that when I get distracted by something and forget to knock out the puck & clean up immediately afterwards.

    GrahamK

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    Define lots. As a noob I thought that a correctly dosed and tamped puck was supposed to expand when the water hit it enough to just touch the shower screen. Is this not right? That would leave a little coffee on the shower screen, but not lots. I often flush the machine a little to wash these grounds off before inserting the portafilter for the next shot.

    This comment may actually be a comment on my espresso machine. I can't overdose at all without the coffee hitting the shower screen as soon as the portafilter is inserted. With an 18gm VST basket I find 17½gms (weighed before and after grinding) to be about the limit in my machine. So if I want a higher dose I need a bigger basket.

    Is my understanding incorrect, or is this machine-dependent?

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    surely when the solenoid vents the pressurised water from the top of the puck at the end of the shot the water sucking back through the shower screen and out the solenoid exhaust would carry some grinds with it that stick to the screen? or am I missing something?

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    Quote Originally Posted by gunda View Post
    a correctly dosed and tamped puck was supposed to expand when the water hit it enough to just touch the shower screen. Is this not right?
    No, its not right. One of the many myths associated with espresso. Aaron is right - do a search for clear PF videos to see if you agree.

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    Senior Member Yelta's Avatar
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    Have not heard anyone mention the portafilter jiggle for a long time The Pullman Tamper | Imat / Quaha Tips | Backflushing I backflush with chemical once a week and perform a short jiggle the with blind basket in place after each session, keeps everything in the coffee path spotless.

    PS, its a jiggle not a twerk.

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    Quote Originally Posted by Aaron View Post
    surely when the solenoid vents the pressurised water from the top of the puck at the end of the shot the water sucking back through the shower screen and out the solenoid exhaust would carry some grinds with it that stick to the screen? or am I missing something?
    Quote Originally Posted by Pete39 View Post
    No, its not right. One of the many myths associated with espresso. Aaron is right - do a search for clear PF videos to see if you agree.
    Now that you mention it, I have seen one of those videos. So what Aaron is saying is I was right - a small amount of the grinds on the shower screen after the shot is normal, but my reasoning as to why they're there was wrong. But "lots" as in the OP may indicate something else.

    Hang on ... then what is all this talk that I've read of a shower screen imprint on the puck being a good sign? Have I misunderstood this too?

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    Senior Member Yelta's Avatar
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    Quote Originally Posted by gunda View Post

    Hang on ... then what is all this talk that I've read of a shower screen imprint on the puck being a good sign? Have I misunderstood this too?
    I believe you have, I most certainly don't want the screen contacting the puck, the 5 cent piece test has had a few mentions in the past few days and here it is again, it's a quick and easy test that will help to establish the correct dosing level for your machine.

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    I meant an imprint on the puck after the shot.

    I understand that you want a small gap - roughly the height of a 5 cent piece - between the top of the puck and the shower screen prior to pulling the shot.

    But I've seen some references to an imprint on the puck after the shot, and this is one of those things that gave me the impression about the puck expanding during the shot. I mean, if the puck passes the 5 cent test before the shot, how do you get a slight imprint after the shot if it doesn't expand? Is a slight post-shot imprint a good or bad thing?

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    TOK
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    You will find that a puck that indicates a nice "dry" post shot imprint of the shower, will leave the cleanest shower (as long as bean freshness, grind and tamp were also optimum).

    I say again......going only on what was stated at first by the tiopic author, who has not been back with any further explanations, I believe his "problem" is the result of UNDER dosing (and I could add, grind too fine, coffee not fresh). All of these will leave a "dirty" shower. Try it and see !
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    Thanks, but I'm still puzzling over my unanswered question: "if the puck [correctly] passes the 5 cent test before the shot, how do you get a slight imprint after the shot if it doesn't expand?" Is this imprint caused by pressure rather than contact?

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    TOK
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    The puck expands because during brewing (erogation) all the voids between the coffee grinds become filled with water.

    Contact.

    Hope that helps.

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    There are some conflicting views being expressed here by people with higher post counts than me.

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    TOK
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    The reason for so called "5 cent test " management of the puck dose is so that there is enough room left for the puck to expand inside the filter, with the group handle applied to the group, when it is saturated with water. The ideal volumetric size of the spent puck, is for it to have expanded enough to have "kissed" the shower, therefore resulting in an efficient brew (all other variables being good). That then allows for the most efficient exhaust of pressure and water from the puck at the end of the brew cycle - in machines that have a group valve - whether it be an electrovalve - solenoid - or a mechanical vavle - eg manual E61 type.

    If the puck is underdosed OR the grinds are too fine OR if the beans are stale, the exhaust at the end of the brew cycle doesnt work properly leaving sloppy grinds to stick to the shower....

    Hope that helps.

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    Junior Member Kanga1788's Avatar
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    Thanks everyone. I've completed the 5 cent test and there was a clear imprint so I guess I'm dosing correctly however I believe my problem could be grinding too fine. I always buy 250g so freshness isn't a concern but I think I'll move the grinder plates apart a bit.

    I also notice there is sometimes a bit of water left over on top of the puck before discarding and I suspect this indicates I've ground too finely.

    Being a home barista is a fun and rewarding but there's plenty to it! My next step is to get a shot glass to measure extraction!
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    Senior Member Yelta's Avatar
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    Quote Originally Posted by gunda View Post
    There are some conflicting views being expressed here by people with higher post counts than me.
    A high post count doesn't indicate any degree of expertise, simply that I or others in a similar position have spent more time posting than others.

    My post was just an opinion, TOK has forgotten more about coffee than I will ever know.

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    What TOK said was what I have read in my research and it meets the common sense test.

    I don't know what to make of those videos with a clear portafilter as there seems to be a large space above the puck pre-shot, whereas what we are talking about is a 5 cent clearance.

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    In the videos, the puck does not expand during extraction. I have never seen any evidence that pucks expand during extraction. There is clear evidence that the puck moves up (and sometimes onto the shower screen if the head-space is small enough) when the brew pressure is released. I personally think that "puckology" is a red herring. You don't drink the puck.

    Having said that, I think the "5 cent test" does give a reasonable way of estimating a starting dose for any given machine. Even better is to get a set of 0.1g resolution scales and use your pallet. Save your money on a shot glass and weigh your dose and your shot, use your pallet and work from there. Happy brewing!

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    TOK
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    Happy to run with what the nice video people reckon, but note that either way it's a moot point because the nett result is the same. The puck moves or expands back onto the shower...

    However, I am afraid I will never agree with those that espouse the idea that you should weigh stuff. The whole process depends on the correct tamped volumetric dose, and that depends on the size of the parti-kills ie the grind setting for the particular type of coffee, with a consistent press or tamp. It doesnmadder what the weight it, what matters is the correct volumetric dose irrespective of grind particle size. And that also varies between the type of group that is fitted to any particular type of machine.

    As always however, people are free to think and do as they please
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  22. #22
    TOK
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    Quote Originally Posted by gunda View Post
    ........I don't know what to make of those videos with a clear portafilter as there seems to be a large space above the puck pre-shot, whereas what we are talking about is a 5 cent clearance.
    A large space at the top if the puck = an UNDER dose. These result in "sloppy" pucks instead of the nice crisp "biscuit", and always leave sloppy grinds behind on the surface of the shower when you remove the group handle. Rather, get the VOLUMETRIC dose right, and everything falls into place nicely.....

    Everything starts from the volumetric dose.

    Some people think its good to use a smaller dose, and they compensate for the resulting faster rate of pour, by adjusting the grind to a finer setting.

    Suggest you try both ways, for a similar rate of pour. Dont worry about whether you get a sloppy puk or not. Just get the similar rate of pour from both methods.

    Cup the resulting brews, and then make up your own mind as to which modus operandi you prefer for yourself It doesnt get any better than that !

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    The point of this thread is what do we find on the shower screen post-shot and what does it tell us about dose. After all, dose is part of the grind-dose-tamp trilogy, and thus is important

    A wet post-shot puck surely must take up more space than a dry pre-shot puck, even if the increase is small. The water isn't going to simply fill up the air spaces. It must swell to some extent.

    So some of what we find on the shower screen from a well-dosed shot IMHO are some grounds from swelling and some from the release of pressure. In an underdosed shot TOK suggests you may get more grounds from a more vigorous release of pressure. I guess you'll get a layer of grounds on the screen from an overdosed shot. I think I'm doing ok, and it sounds like the OP is as well.

    I think that the transparent pf video seems to indicate a significantly under-dosed shot and I still don't know how to interpret it. I think there's a slight increase in volume, but at that level how would you tell? If a correctly dosed shot only expands by the height on a 5 cent piece, the increase in that puck would be too small to see. What you do see is the explosive release in pressure as TOK suggested. Just move along ... nothing to see here.

    [As a noob, I find it easiest to fine-tune the dose accurately and get repeatability of the dose with scales, and cross-checking the dose by the tamp height. This should be a reasonable proxy for volume if the grind isn't changing too much. I think there's less scope for variation compared to fill - collapse - fill - level approaches, which surely must be a fairly imprecise way of getting a consistent volume.]

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    Quote Originally Posted by TOK View Post
    The "5 cent test " management
    People, don't forget the alternative to the coin test is the rice test and in my opinion neater. Go into youtube and google it but basically you keep putting long grain rice into a dry basket (and make sure the screen is dry as well otherwise the rice stick to the screen) until you just can't lock the group handle in. Take out a few grains at a time until you can lock your handle without resistance from the rice. Then place your tamper on the basket and note where it finishes. A tamper with lines on the edge eg pullman comes in very handy here. This is the spot your tamper should finish after tamping the coffee. I even put the rice back into the rice container which keeps my wife happy.

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    Senior Member Yelta's Avatar
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    Have heard of the rice method previously but have never been tempted to try it, guess it would work with any small grain, seems like quite a bit of stuffing around compared with the 5 cent piece test.

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    Give it a go Yelta! You only live once ! Just grab half a cup of grain rice not arborio from the pantry. Takes 5 minutes and there is no wastage of valuable coffee. It's accurate because the rice doesn't crush down like coffee so where the tamper finishes on the bed of rice is exactly where you want the tamper to finish after tamping.

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    I found it odd that arborio rice was not good for this test in an Italian espresso machine, after all, isn't it the ingredient in risotto!?!? But it's too clumpy. You want the thinnest grains you can find to get the finest control.

    The rice test is a lot less messy than the 5 cent test and easier to add or subtract to fine tune the tamp height. But the 5 cent test is a little more precise IMHO and it's worth doing that as well after the rice test to double check.
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  28. #28
    TOK
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    Blokes you can do it with anything you like including gasp horror......ground coffee. Just make sure the shower is dry.....the machine doesnt even need to be switched on, all you are trying to determine is the height in the filter at which the tamped puck just kisses the shower Or if you wish, where it just misses the shower. It will vary from machine to machine (due to different design and or machining of individual group heads). That will be the height in the filter that you should always try to achieve, remembering that the density of the puck will change from coffee blend to coffee blend, or SO to SO, during the staling process, and by the setting of the grind that you choose. Irrespective of all those variables, you always need to try and achieve that same height (or volume) in your filter when the puck is tamped down, for the espresso principle to work at its best.

    And that will then show you if you have set the correct grind or not. You then change the grind to suit, not the dosed tamped height of the puck which remains the same. Everything works from the puck back.

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    Quote Originally Posted by TOK View Post
    all you are trying to determine is the height in the filter at which the tamped puck just kisses the shower Or if you wish, where it just misses the shower.
    Yep, that's all we're trying to do. We're not looking to make this overly complex, despite what it might seem.

  30. #30
    Senior Member Yelta's Avatar
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    Quote Originally Posted by gunda View Post
    We're not looking to make this overly complex
    Not too sure about that.

    The subject has been covered time and again, it's a simple concept, all we're trying to do is get the dose into the ball park, from there on everything is fine tuning.

    The 5 cent piece test has been around for ages and does the job with the materials at hand, a while back someone suggested rice, at one stage there was even a misunderstanding about whether or not to use cooked or uncooked rice now we're being advised as to the best type of rice to use (don't use arborio) crikey!, seriously, I guess you could use Quinoa, poppy seed, pearl barley, split peas or any other grain that tickles your fancy.

    As far as the 5 cent test being messy and expensive (wasted coffee) it's neither of these things, spend a few moments reflecting on what your trying to do, if you've reached this stage your pretty darned close anyway, so, grind, tamp or whatever you do, drop the coin on top of the puck, do the test, regardless of the result pull the shot and have a brew while you reflect on the results, if you got the imprint you we're looking for, great, if not make some notes, mental or written and do the test again later making the appropriate adjustments.

    Once you get the result your seeking that's it, forget about it until you change your machine, basket, seal or whatever, I did the test once on my machine almost 5 years ago and have not had to repeat it.

    It matters little to me whether you use coffee, rice, or custard, what does concern me is misinformation, i.e. coffee is messy and expensive, seriously, it's neither of these things, it's the substance our snobbery revolves around and is readily available, so, why not use it?
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    The comment about the arborio was meant to be humorous.

    The mess with the 5 cent test is minimal, but I dislike mess.

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    TOK
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    Quote Originally Posted by gunda View Post
    Yep, that's all we're trying to do. We're not looking to make this overly complex, despite what it might seem.
    I dont know where the "overly complex" comment came from. It is quite simple, get the dose right and everything else follows that. Always keep the dose a constant while the other variables change around that. Simple concept, done.

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    Quote Originally Posted by TOK View Post
    However, I am afraid I will never agree with those that espouse the idea that you should weigh stuff. The whole process depends on the correct tamped volumetric dose, and that depends on the size of the parti-kills ie the grind setting for the particular type of coffee, with a consistent press or tamp. It doesnmadder what the weight it, what matters is the correct volumetric dose irrespective of grind particle size. And that also varies between the type of group that is fitted to any particular type of machine.

    As always however, people are free to think and do as they please
    I weigh my doses because:
    a) the mass of the dose doesn't change during tamping (whilst the volume does).
    b) the volume of grinds pre-tamp varies the grind size and level of compaction (whilst the mass does not).
    c) It is easy to dose exactly the same quantity, or to know how much more or less I have dosed, before I tamp.

    I don't really follow how "the correct tamped volumetric dose" can be dependent on particle size only and not mass. Changing one will change the other. I could equally say that particle size doesn't matter so long as you can tamp the required mass into the "correct tamped volume".

    In any case, judgment of what is the "correct" grind size/mass isn't based on their objective measurement, but rather on some other parameter(s); presumably the pour/the taste.

    Unless perhaps I am missing something.
    Last edited by MrJack; 11th September 2014 at 07:05 PM.

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    Quote Originally Posted by gunda View Post
    The comment about the arborio was meant to be humorous.

    The mess with the 5 cent test is minimal, but I dislike mess.
    +1 on the mess and wastage. That's why I use rice as a viable alternative to the 5 cent test and I wanted to put it out there so people have that option. I don't care which way you do it, whatever works for you but there is no reason to be cynical about another method.

    Despite sounding humorous small grain rice compacts better than the larger grain arboria and provides a more accurate result.



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