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Thread: Convex vs Flat base tamper

  1. #1
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    Convex vs Flat base tamper

    Gene Cafe Coffee Roaster $850 - Free Beans Free Freight
    Hi,
    I am in the process of getting a tamper probably will end up getting a Pullman. Just wondering what difference does a convex base tamper make to the shot?

    cheers

  2. #2
    Senior Member Koffee_Kosmo's Avatar
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    Re: Convex vs Flat base tamper

    Hey BigM
    I have both the flat and convex tampers both Pullmans
    For my machine that has a convex filter screen I use the convex most of the time
    The convex tamper just works better for me on this machine

    So what difference does it make to the shot? Flat or Convex
    Well I canít say that there is any real difference to the taste

    But the procedure or my tamp routine is easier with the convex tamper for my Bezzera


    KK

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    Site Sponsor pullman's Avatar
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    Re: Convex vs Flat base tamper

    Quote Originally Posted by bigmomma link=1220438656/0#0 date=1220438656
    Hi,
    *Just wondering what difference does a convex base tamper make to the shot?

    The theory is to have the surface of the puck matching the shape of your showerscreen.... so there is minimum gap for the puck to expand into.... and that gap is uniform across the width of the puck..... and that will reduce the likelihood of channelling.

    So if your machine has a flat showerscreen..... then a flat based tamper would be better..... if the showerscreen is convex..... a convex would be better...

    However, probably 99% of our customers here in Australia choose a flat base.... the convex being far more popular in Europe and even America....

    It really is a matter of personal choice and what works best for you..... Me, I prefer the convex base with my La Cimbali.... its showerscreen is also convex.

    Robin.

  4. #4
    Mal Dimal's Avatar
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    Re: Convex vs Flat base tamper

    I prefer the Flat Base..... You guessed it, the shower-screen on my Bezz is flat too, ;)

    Mal.

  5. #5
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    Re: Convex vs Flat base tamper

    Quote Originally Posted by Pullman Espresso Accessories link=1220438656/0#2 date=1220443614
    probably 99% of customers here in Australia choose a flat base.... the convex being far more popular in Europe and even America...
    You might need to revise that statistic to read that 99% of your tamper sales are flat bases. I suspect this might well be due to the internet effect, - ie. Greg offered only flat tampers for so long that when he started offering convex, people asked about it and the response from everyone was well, I bought a flat-based tamper and I am very happy with it; cant actually tell you about the convex based tamper because I havent used it. Faced with that sort of a response, I think that most people would go with the known quantity, perpetuating the cycle of going with the flat-based tamper.

    From memory, I think that the pro barista market is basically the exact opposite - 70 or 80% convex, or thereabouts. I cant remember whether that was for Espro only or for tampers in general. Again, it might well be internet effect - ie. a bunch of pros writing up about how much they like their convex base and the rest following suit.

    Quote Originally Posted by Pullman Espresso Accessories link=1220438656/0#2 date=1220443614
    The theory is to have the surface of the puck matching the shape of your showerscreen.... so there is minimum gap for the puck to expand into.... and that gap is uniform across the width of the puck..... and that will reduce the likelihood of channelling.

    So if your machine has a flat showerscreen..... then a flat based tamper would be better..... if the showerscreen is convex..... a convex would be better...
    I have heard that one, too, but I think that it is worse at holding water than a channeling puck. One problem is that I have heard that the mythical illy glass portafilter video clearly shows that the area above the puck is filled with water very early on. This makes intuitive sense - surely you couldnt get up to espresso brew pressure if the headspace werent full of water? Another problem is that the theory seems to presuppose even distribution of water, at least at the initial stages. But we know that this isnt the case; most machines have some sort of diffusion plate or bolt in the centre and if you run water through the group, you seldom see water dribbling down perfectly distributed, as though from a shower head; it only really seems to do that immediately after you have cleaned your machine. Yet another problem is that another theory, which makes sense to me, is that under pressure the water forces the ground coffee down, maintaining the head space; the puck is thought to only swell to push against the shower screen after the pressure is discharged.

    Another theory that I have heard is that convex tampers push the coffee towards the edge and, so, seal the edge of the puck against channelling. I think that it was Greg that showed that this is also BS; the coffee will be pushed down. This theory also implies that an undersized convex tamper will produce channeling if you use it multiple times to cover the whole puck area. But, in fact, tamping multiple times with an undersized tamper is supposed by many people, including Mark Prince, to prevent channeling ... for whatever reason (havent tried it myself). Mike Yung and Co were so impressed by it that they even used Marks prototype new tamper in the WBC this year.

    Just wondering what difference does a convex base tamper make to the shot?
    To actually attempt to answer this question, I would have to say that it makes little, if any, difference. I, personally, thought that a convex tamper resulted in slightly more consistent shots when using it in a busy espresso bar, but (a) I didnt try to measure the effect, (b) I wasnt comparing two tampers that were identical except for the curvature of the base and (c) I have since fooled around with an ill-fitting plastic tamper quite a bit, finding that its actually quite possible to get decent results consistently even with that.

    If the tamper base does actually make a difference, its impact on your shot is definitely going to be much less than the impacts of the other more significant variables, the most important of which, IMHO, include having decent coffee in the first place and dosing consistently. That being the case, Id personally go for the convex base or the c-flat, just because I at least have a vague suspicion that it might result in more consistent shots.

    Cheers,

    Luca
    chippy likes this.

  6. #6
    Site Sponsor pullman's Avatar
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    Re: Convex vs Flat base tamper

    Quote Originally Posted by luca link=1220438656/0#4 date=1220449194

    You might need to revise that statistic to read that 99% of your tamper sales are flat bases.
    *

    Yep..... done ;)

    I suspect this might well be due to the internet effect,
    Agreed Luca...... I think much of what is accepted as "law" when talking about coffee practice (and not just coffee *::)).... is that if it has been said often enough on the internet.... and loud enough.... it must be true!

    There have been many theories as to why convex or flat (or even concave) bases are better...... I know I get more consistent results from a convex..... (and I do happen to have the odd tamper around both flat and two degrees of convex)...... why is that? Could be any one of the theories... except for the pushing coffee towards the edge.... which Greg did prove doesnt happen.

    But as I said above, the best base shape, just like brand of tamper, whether fitted or not, what type of handle gives best grip/feel etc... etc.... are all a matter of personal choice - what works best for you...... and it is neigh on impossible for someone else to determine what that will be.

    About the best which can be offered is an educated guess based on certain "assumptions" and we all know that to assume makes an ASS out of U and ME.... ;) ;D ;D ;D

    Robin

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    Re: Convex vs Flat base tamper

    Bit of a bump but did anyone ever find any pictures or video of said "illy glass portafilter"??? Would love to see.

  8. #8
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    Re: Convex vs Flat base tamper

    Behmor Brazen - $249 - Free Freight
    There is an image of it on page 150 in the book:
    "The Book of Coffee" by Illy.



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