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Thread: Headspace, crema bubbles and the cooling flush.

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    Senior Member speleomike's Avatar
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    Headspace, crema bubbles and the cooling flush.

    Gene Cafe Coffee Roaster $850 - Free Beans Free Freight
    Hi all

    I have been experimenting a lot today with my new Galatea (no one has commented on my take on Dali in the older topic, oh well). Im trying to get my grind and tamp right as it needs to change from my Silvia. The shots are good from the Galatea but could be better. I have tried today differing grinds with the Weis technique using a needle, with and without a mid-tamp, and Anyhow I have some pics here I would like advice on.
    - Bean is Ethiopian Harrah, nunu nicely made me a kg so I have lots to play with. 5 days rest.
    - Basket is a double one, 24 mm deep.
    - Grinder is a Rocky, doserless. It does clump a bit.
    - Tamping method. I generally fill with wiggling of the PF against the prongs to distribute. A light tap on bench then brush off flat with a chopstick. Then tamp with Espro tamper.

    Headspace: Some sites advocate to have some headspace above the coffee, i.e. a gap between the coffee and the screen. With my Silvia I always filled till I got the small impression of the screw in the puck - absolutely no headspace. With the Galatea one gets no impression but I would have thought one would fill till it just touched the screen. I tried a few with some headspace but I think one ends up just underdosing. Pic 1 shows the puck that had headspace. It looks like flowing water has patterned the surface. The coffee from this was just acceptable. Pic 2 shows a puck with no headspace. Question: for an E61 machine should one have headspace?

    Crema Bubbles: In some of my shots I get largish bubbles in the crema, Pic 3. Other shots have smoother appearance to the crema and less bubbles, Pic 4. Shots with bubbles in the crema also tend to have a darker crema. Question: Is the darker crema and bubbles indicative of too high a temperature of extraction?

    Flushing: I have seen the videos of the HX water dance and the cooling flush. It shows spitting of hot water which then settles down indicating the temp is now stable and correct for a shot. With my Galatea if its been on for a while and I open the brew handle I get steam from the water coming out the brew head but no spitting like the videos. I can let it run but there is really no change to the water exiting the group head. I therefore just flush about 50mL to 1/2 fill the espresso cups just before a shot. Question: Does anyone with a Galatea see really hot water spitting like the videos show.

    Mike





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    Senior Member Koffee_Kosmo's Avatar
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    Re: Headspace, crema bubbles and the cooling flush

    Regarding Flushing I get the same as you

    Regarding the head space I leave aprox 1mm gap to the screen to allow for expanssion it gives me great results

    Yes I did like the take on Dali :)

    KK

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    Re: Headspace, crema bubbles and the cooling flush

    With cooling flushes, machines like these tend to have very stable temperature. So unless the machine is idling for the last 2hours+ youre not going to need a 200ml flush. Even after a 2 hour idle time, i only flush about 100-150mls of water from my domobar.

    With dosing on the domobar(dont know if it transfer to the galatea), if you dose up till there is no headspace and the puck scrapes against the shower screen, it will crack the edges of the puck and youll get heavy channeling.

    So you want a dose which touches the screen when your PF is fully locked. If it touches even before you lock it in, it will push the puck to the left and the right will channel.

    Down dosing will work, but youll need a finer grind because ur getting less resistance with the lower dose.

    With crema appearance, I reckon its a lot to do with the coffee youre using and the freshness. Not so much the extraction. However, an under extracted shot will have very pale crema and an over extracted shot will have a darker crema but you should be able these by looking at the pour.

    Larger bubbles are quite common if your beans are VERY fresh
    Darker crema and flecking is also more common in blends and darker roasts.

    I generally start drinking everything 7 days+

    Hope that helps!

    Correct me if im wrong :D Just my 2cents

    Gav


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    Senior Member speleomike's Avatar
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    Re: Headspace, crema bubbles and the cooling flush

    Hi Gav

    Ah so idling for 30 mins means its temp is prob still fine. Lots of sites say "idling for a while" but dont say how long a "while" is. I havent done big flushes of 200 mL but just 50 mL before each pour.

    Maybe Im overfilling my baskets. OK so I do need some headspace to stop any movement of the coffee when locking in. I was very used to the small screw on the Silvia :-) I will fill & tamp and lock in and then remove the PF to see at what fill level the basket touches.

    You may be right about the edges of the puck cracking. The pour starts out quite nice after about 6 seconds delay, its nice mouse tails and viscous but only for about 4 seconds, then the flow is very runny. Not blond but its lost much of its deep red/brown.

    I have been getting the larger bubbles often in most of my own roasts which have been from 7 to 10 days old so Im suspecting my technique.

    Mike

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    Senior Member speleomike's Avatar
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    Re: Headspace, crema bubbles and the cooling flush

    Hi all

    Given what Gav mentioned I went and filled the basket with settled, but not tamped coffee and loaded it into the group head. Then removed it. If there was no marks from the screen I added more, settled it by tapping and loaded again. Once I had a faint mark I tamped and reloaded. When removed there as expected was no mark.

    The weight of coffee for this is 14-15 gms. The scales alternative between 14 and 15 as they are only to 1 gm resolution. It just so happens that the Espro tamper for this fill is just flush with the top of the basket. The Espro thickness is 11 mm so this places the tamped coffee surface 11 mm below the basket surface. This is deeper than what I have been using.

    Ill try tomorrow to use this level and re-adjust the grind down to get my 25mL in 25s rate and see how the pour looks.

    Mike

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    Re: Headspace, crema bubbles and the cooling flush

    Dont know how much the galatea basket takes but 18/19 grams touches the screen, 20 is still good but a little over 20, 21 grams and it scrapes the screen.

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    Senior Member speleomike's Avatar
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    Re: Headspace, crema bubbles and the cooling flush

    Hi
    The basket Im using is 24mm deep. Whats yours in depth?
    Mike

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    Re: Headspace, crema bubbles and the cooling flush

    Cant really get an accurate measure but its about 23mm.

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    Re: Headspace, crema bubbles and the cooling flush

    Hi

    Actually I can get 18 gm in. The 14 gm was when it just touched untamped. Then tamped of course it was clear. I weighed 18 gm into the basket then tamped and it just by a smidgin touches the screen. A few grains were disturbed so tomorrow Ill try for an 18 gm load.

    Mike

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    Senior Member clubbi4's Avatar
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    Re: Headspace, crema bubbles and the cooling flush

    Quote Originally Posted by speleomike link=1214654455/0#0 date=1214654452
    Hi all

    I have been experimenting a lot today with my new Galatea (no one has commented on my take on Dali in the older topic, oh well). *Im trying to get my grind and tamp right as it needs to change from my Silvia. The shots are good from the Galatea but could be better. *I have tried today differing grinds with the Weis technique using a needle, with and without a mid-tamp, and * Anyhow I have some pics here I would like advice on.
    - Bean is Ethiopian Harrah, nunu nicely made me a kg so I have lots to play with. 5 days rest.
    - Basket is a double one, 24 mm deep.
    - Grinder is a Rocky, doserless. It does clump a bit.
    - Tamping method. I generally fill with wiggling of the PF against the prongs to distribute. A light tap on bench then brush off flat with a chopstick. Then tamp with Espro tamper.

    Headspace: Some sites advocate to have some headspace above the coffee, i.e. a gap between the coffee and the screen. *With my Silvia I always filled till I got the small impression of the screw in the puck - absolutely no headspace. *With the Galatea one gets no impression but I would have thought one would fill till it just touched the screen. *I tried a few with some headspace but I think one ends up just underdosing. *Pic 1 shows the puck that had headspace. It looks like flowing water has patterned the surface. *The coffee from this was just acceptable. Pic 2 shows a puck with no headspace. *Question: for an E61 machine should one have headspace?

    Crema Bubbles: In some of my shots I get largish bubbles in the crema, Pic 3. *Other shots have smoother appearance to the crema and less bubbles, Pic 4. *Shots with bubbles in the crema also tend to have a darker crema. *Question: Is the darker crema and bubbles indicative of too high a temperature of extraction?

    Flushing: I have seen the videos of the HX water dance and the cooling flush. It shows spitting of hot water which then settles down indicating the temp is now stable and correct for a shot. *With my Galatea if its been on for a while and I open the brew handle I get steam from the water coming out the brew head but no spitting like the videos. I can let it run but there is really no change to the water exiting the group head. I therefore just flush about 50mL to 1/2 fill the espresso cups just before a shot. *Question: Does anyone with a Galatea see really hot water spitting like the videos show.

    Mike



    Your results would improve dramatically with a decent grinder. Keep the rocky for decaf and invest in a Mazzer Mini...

    Good Luck

  11. #11
    Senior Member Koffee_Kosmo's Avatar
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    Re: Headspace, crema bubbles and the cooling flush

    I am contemplating in getting a convex base tamper (U.S./1.5mm curve) to accommodate the shape of the head of the Galatea
    It may be another tool in my Domus Barista Kit for fine tuning *::)

    KK

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    Re: Headspace, crema bubbles and the cooling flush

    Hi Kosmo

    Thats an interesting point. I have two tampers, a Tobys Estate (convex) and a Espro (flat). With the Silvia I used the convext tamper and with the Galtea I have been using my new Espro tamper:

    Silvia screen is flat + convex tamper = most headspace in middle.
    Galatea screen convex + flat tamper = most headspace at periphery.

    The shape of the headspace then is completely different in the two cases; plano-convex vs. concave-plano. Im not sure if its significant or not.

    Mike

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    Re: Headspace, crema bubbles and the cooling flush

    Greg and I have differing opinions on this issue.... Greg preferring flat whereas I prefer Convex (on my machine at least).....

    My La Cimbali M20 has a convex showerscreen.... and I dose so that the unextracted puck just touches the showescreen.....

    If I use a flat based tamper there is a widening gap as you move towards the rim of the basket. When water hits the puck it expands..... in the centre there is no where for it to go.... and becomes denser.... near the periphery there is a space and the puck can expand.... remaining at a lower density.

    As water will always take the path of less resistance..... more will flow through the puck near the edge and less near the centre..... so the puck near the edge can tend to be overextracted.

    If you down dose so the puck is much lower than the showerscreen this wont apply.... or apply but to a far reduced amount (depending how much "gap" exists between the showerscreen and the surface of the puck).

    So IMHO, best results should be obtained when the profile of the tamper matches the profile of the showerscreen...... But that is only an opinion based on my theory and experience (for what it is worth) :-/

    Robin.

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    Senior Member Koffee_Kosmo's Avatar
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    Re: Headspace, crema bubbles and the cooling flush

    Yes Robin you put in words exactly what I was thinking
    I have been tamping with the flat pamper leaving a gap of approximately 1mm or less for the reasons you give above

    Thatís why I was contemplating a convex tamper
    My thinking was that it makes sense to match the shape of the puck to the shape of the filter head
    Now I think I will get one
    Robin will the American 1.5 mm curve be suitable for the Bezzera Group head

    KK



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    Re: Headspace, crema bubbles and the cooling flush

    KK,

    The convex bases we supply (and I use) are 1.5mm convex. It works perfectly on my La Cimbali and other machines with a Convex showerscreen.

    Whilst we dont sell a lot of these bases in Australia, they sell very well into Europe and the Americas..... and we have been receiving very good feedback from those who have purchased them (for use on a range of different machines).

    Robin.

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    Re: Headspace, crema bubbles and the cooling flush

    Hi
    re Tampers:

    I use a convex Pullman on my Giotto. *I am very happy with the results.
    The top of the un-extracted puck sits flush with the shower screen.

    David

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    Re: Headspace, crema bubbles and the cooling flush

    Thanks Robin
    I will most likely order one of those Barista models when they become available along with the Synesso baskets

    Thanks for the input dumiya

    KK


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    Senior Member speleomike's Avatar
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    Re: Headspace, crema bubbles and the cooling flush

    Hi all

    I have been slowly moving through the parameter space for grinding and tamping but still havnt got it perfect yet. Taste is not sour or bitter but its maybe acidic and flat.

    I am now using a tamper that has a convex base that better matches the screen. I found earlier that 18 gm is close to just touching the screen. Im setting a grind, grinding excess into a yogurt container, using a needle in the end of a chopstick to swirl it around and break up clumps. This flufs it up nicely. Then weighing 17-18 gm into another yogurt container. Then tipping that into the PF and levelling it off. Then tamp. I think this is pretty reproducible.

    Grinds < 11 is too fine but the puck is dryish. At 11 its OK grind but puck shows water flow marks on its surface so I think there is too much headspace. At grinds 12 and more I get blonding I think too early, at about 15 seconds.

    So I still havent nailed it. Im looking for a more viscous flow and a sweeter taste I think if that is possible with these beans.

    Mike

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    Re: Headspace, crema bubbles and the cooling flush

    Hey Mike,

    So, a number of months on, how has the experimentation gone? What sort of headspace have you worked out?

    (and sorry for the grave dig).

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    Senior Member speleomike's Avatar
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    Re: Headspace, crema bubbles and the cooling flush

    Hi ona

    Well lots has changed. The grinder is no longer a Rocky - its now a dosered stepless Macap M4. That means the blades are sharp and the doser means I dont get clumps so no Weis technique with yogurt containers and needles :-)
    Result = flow is more smooth, thicker and sweeter.

    The other thing I found is that in my initial playing with the Galatea at home in the first few days I was using an Ethiopian coffee whereas a Brazilian one produces for me a better coffee.

    I also now have a Pullman Barista Tamper with flat base. It was hard to decide what is best amount all the theories - flat or curved. I went with flat as it was available. We really need a fibre optic cable inserted into a group head and video what goes on inside in slow motion.

    As for headspace, Im using about 1-2mm. I still havent decided what the perfect headspace is. Maybe what we need is an knurled adjustment ring on the PF so we can raise or lower the PF basket until we feel the puck touching the screen - then you stop. That way one could have zero head space but no risk of damaging the puck.

    Mike

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    Re: Headspace, crema bubbles and the cooling flush

    Mike, to help you with dosing and clearance space I need more info. What is the pour like. Does it start slow and speed up or is it a constant speed. Does your pour hang straight from the spouts or does it curve inwards? Are you timing your pours, if so can you give an idea of what happens when.
    What does the espresso taste like?

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    Re: Headspace, crema bubbles and the cooling flush

    Mike
    For the Bezzera Domus
    When I used the flat Pullman tamper I tamped down 8mm into the basket to allow for a 1mm gap at the filter screen

    It is similar with the new Barista convex tamper but the measurement is to the centre of the puck

    I find that the ideal spot is the highest guide line (handle end) of your Barista tamper
    KK

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    Re: Headspace, crema bubbles and the cooling flush

    Ive got a convex tamper and it gives me better results than my flat one does.

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    Re: Headspace, crema bubbles and the cooling flush

    Quote Originally Posted by 657E7B7E20110 link=1214654455/23#23 date=1233135377
    Quote Originally Posted by 606F7661616A37030 link=1214654455/9#9 date=1214693792
    Quote Originally Posted by speleomike link=1214654455/0#0 date=1214654452
    Hi all

    I have been experimenting a lot today with my new Galatea (no one has commented on my take on Dali in the older topic, oh well). *Im trying to get my grind and tamp right as it needs to change from my Silvia. The shots are good from the Galatea but could be better. *I have tried today differing grinds with the Weis technique using a needle, with and without a mid-tamp, and * Anyhow I have some pics here I would like advice on.
    - Bean is Ethiopian Harrah, nunu nicely made me a kg so I have lots to play with. 5 days rest.
    - Basket is a double one, 24 mm deep.
    - Grinder is a Rocky, doserless. It does clump a bit.

    Mike



    Your results would improve dramatically with a decent grinder. Keep the rocky for decaf and invest in a Mazzer Mini...

    Good Luck

    Sorry, I seem to have stuffed up a bit here!

    So, now: That response worries me quite a bit. I am a very *very newbie and I have been looking around to purchase a new machine in the Expobar, Giotto, Galatea, etc level. I have a Rocky doserless grinder which I have assumed would be adequate for any of these or similar machines. Are you saying that such a grinedr would not be appropriate/inferior/inadequate to use with these machines. My budget would only just cover the coffee machine and I dont think I can run to another grinder. But if you think I wont achieve the best result from the coffee machine I may have to rethink the whole exercise.

    Will really appreciate any thoughts from the gurus.

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    Re: Headspace, crema bubbles and the cooling flush.

    Buying a more expensive grinder may fix a problem that doesnt exist. Sure the mazzer is a better grinder in terms that it has finer adjustment and the doser removes clumping, but I wouldnt buy a new grinder unless i was SURE the Rocky wasnt up to the job.

    If you are buying a new machine, talk or visit one of the sponsors on the left who would be more than happy to test a machine with your grinder. You may find your technique has a bigger impact on results than just a grinder.

  26. #26
    Senior Member Koffee_Kosmo's Avatar
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    Re: Headspace, crema bubbles and the cooling flush.

    Quote Originally Posted by 4847421C1316250 link=1214654455/25#25 date=1233137167
    Buying a more expensive grinder may fix a problem that doesnt exist. Sure the mazzer is a better grinder in terms that it has finer adjustment and the doser removes clumping, but I wouldnt buy a new grinder unless i was SURE the Rocky wasnt up to the job.

    If you are buying a new machine, talk or visit one of the sponsors on the left who would be more than happy to test a machine with your grinder. You may find your technique has a bigger impact on results than just a grinder.

    I second that
    Its good advice

    KK

  27. #27
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    Re: Headspace, crema bubbles and the cooling flush.

    Does sound like good advice. On the same line, do any of them do loaner mazzer/macap to test on existing home machines?

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    Re: Headspace, crema bubbles and the cooling flush.

    Thanks for the advices but I live in a regional town and its not easy to make such an exploratory visit. But I shall continue delving into discussions.

  29. #29
    Senior Member Koffee_Kosmo's Avatar
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    Re: Headspace, crema bubbles and the cooling flush.

    Quote Originally Posted by 283336336D5C0 link=1214654455/27#27 date=1233199194
    Thanks for the advices but I live in a regional town and its not easy to make such an exploratory visit. But I shall continue delving into discussions.
    Tojo
    The only course of action you have is to try your Rocky out on the future new machine
    If you are getting good results then your problems are solved
    I dont want to speculate any further until you eliminate a perceived problem

    KK

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    Re: Headspace, crema bubbles and the cooling flush.

    Thanks KK, I can wait for a while.
    Its just that the comment by clubbi4 spooked me a bit [me being the complete novice].

    Good morning



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