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Early dark drops - Why?

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  • ddthiel
    replied
    Re: Early dark drops - Why?

    Water pressure straight out of the shower is one thing - the pressure the machine is pumping. However, once into the grinds, the pressure of the water doing the actual extraction is not the same, necessarily. That is to say: the water isnt flowing freely through the grinds - which changes as the grinds expand during extraction (and Ive noticed as the coffee gets farther from roast date).

    Of course, what Rocky has posted makes a lot of sense, too...

    Leave a comment:


  • Rocky
    replied
    Re: Early dark drops - Why?

    I dont think I have ever seen the phenomenon you describe, but the only thing that makes sense to me is that maybe the initial seconds in the pour carry the finest particles of grind straight through. Once the puck has been saturated, the fine particles will still be there but they wont be discernable due to the more efficient extraction that is occuring.

    Leave a comment:


  • Yash
    replied
    Re: Early dark drops - Why?

    Originally posted by 2B2B3B27262A234F0 link=1330306410/20#20 date=1330697712
    Lets say out of a given shower, water streams at a certain pressure (SUnbeam claims 15 bar on mine) and hits the grinds.  If they are too small or too much or packed too tight, or any combination of these, then the pressure of the exiting stream can be GREATLY reduced.
    Hi ServingRoyalty,

    Thanks for your detailed reply, and sorry for missing it. I dont quite get what you say about pressure being greatly reduced if the coffee bed is choking the machine.  If anything I would expect the pressure to increase to the maximum possible pressure of the pump or the setting of the OPV (over pressure valve).

    Makes sense?

    Leave a comment:


  • ddthiel
    replied
    Re: Early dark drops - Why?

    Of course, I havent got a nice machine, but I experiment a bit with how much I dose (the convenience of a cheap machine is there is no pressure release valve if I WAY overdose, not like the lovely Elen). 

    Anyhow, coffee is essentially black.  Crema is a frothing related to the oils extraction under pressure, or something like that, right? 

    Lets say out of a given shower, water streams at a certain pressure (SUnbeam claims 15 bar on mine) and hits the grinds.  If they are too small or too much or packed too tight, or any combination of these, then the pressure of the exiting stream can be GREATLY reduced.  If it gets reduced too much too quickly after hitting the grounds, then the extraction of oils may not be great in the initial bit of water passing through and you just get a trickle of... coffee... black... because coffee is black... okay, point made. 

    In my experimenting, if I over-dose, I REALLY over-dosed.  that meant that all I got was black drops.

    Yash, in your case, if you had blocked the pressure only by a little too much (and you are experienced enough that you arent likely going crazy, I think) then you may have got the black drops of over-fine/over-packed/over-tamped coffee for a few seconds.  Then, the grounds may have expanded as they should and the rest of the pour was able to pass through the puck with a steady pressure and do what its meant to. 

    As for what went wrong since your coffee routine is just that: maybe it was a high-humidity day and the grounds behaved differently.  Or maybe it was fresh beans that hadnt settled in yet - so they were grinding funny.  Those are the two reasons that could affect how the pour went through your grounds which are outside of your control vs. your grind / your dose / your tamp.

    Somebody give me some input since Im trying to figure it all out myself and this is a best guess based on what Ive read in this thread; on top of my home experience with a decidedly second-rate machine; as well as studying the workings of the lovely Elen (Mrs. Expobar to you!) at the office.

    Yash, I wonder if this hits the mark for you at all.

    ServingRoyalty
    is causing me to lose weight.

    Leave a comment:


  • Yash
    replied
    Re: Early dark drops - Why?

    Originally posted by 04312624142C312E222F27430 link=1330306410/18#18 date=1330433759
    Given the above a possible explanation is:

    The pit could indicate channelling from an incomplete tamp as the tamper cannot tamp properly around the ridge. Once the beans start to swell, the pit closes up and the channelling stops.

    Greg
    That makes sense to me.
    Regarding the pits however, I still used to get them after very careful distribution and tamping.  Since lowering my dose to just below the basket groove theyve disappeared.

    Leave a comment:


  • GregWormald
    replied
    Re: Early dark drops - Why?

    Originally posted by 243C2E353433313C29343B5D0 link=1330306410/13#13 date=1330405704
    One thing I was doing around that time was slightly over-dosing.  I have ridged baskets and the optimum coffee level my machine is just below the ridge.  I used to often dose into the ridge and this would often cause a pit to form on the edge of the puck (Im guess from excessive pressure). Perhaps it was related to this...
    Given the above a possible explanation is:

    The pit could indicate channelling from an incomplete tamp as the tamper cannot tamp properly around the ridge. Once the beans start to swell, the pit closes up and the channelling stops.

    Greg

    Leave a comment:


  • Yash
    replied
    Re: Early dark drops - Why?

    Originally posted by 79757C7C7F7F79726873691A0 link=1330306410/8#8 date=1330371730
    This happens to me if i dont flush out the group head first...
    Wise words, and yes, its mainly just curiosity - an unexpained mystery.  Doesnt hurt to figure out the cause.
    Originally posted by 7B69716E727F79757C7C7F7F7D6F631A0 link=1330306410/16#16 date=1330421966
    By that I mean inserting the empty group handle into the group head and running some hot water through it pretty soon after running the shot to disperse any grinds caught up there and to flush the group head

    this also happens to me occasionally - seems less of an issue if I drop say a half a cup of water through the group head prior to inserting the handle and running the shot - purge before and after each extraction - thats my moto!
    Thanks again for the advice.  But this still doensnt make sense to me since any left over grind stuck to the shower screen would still have to migrate throught the tamped coffee bed to end up as early dark drips....

    Anyway time to abort!  Thanks to all for trying.

    Leave a comment:


  • askthecoffeeguy
    replied
    Re: Early dark drops - Why?

    Originally posted by 58405249484F4D40554847210 link=1330306410/9#9 date=1330381468
    Hi askthecoffeeguy,

    Thanks for all the advice.  Do you mean flush out stuff from the group handle (i.e. the area under the basket) or in the group head itself (i.e. above the shower screen)?
    I always do a clean-out/cooling flush before pulling a shot.  Generally Ill do this without the handle attached.  Not sure about my friend.

    Thanks
    By that I mean inserting the empty group handle into the group head and running some hot water through it pretty soon after running the shot to disperse any grinds caught up there and to flush the group head

    this also happens to me occasionally - seems less of an issue if I drop say a half a cup of water through the group head prior to inserting the handle and running the shot - purge before and after each extraction - thats my moto!

    Leave a comment:


  • artman
    replied
    Re: Early dark drops - Why?

    Originally posted by 4B7F687E65524E626B6B68680D0 link=1330306410/14#14 date=1330417398
    If you end up with a great crema and coffee, why does anything need to be wrong or have been caused by something you felt may not have been done correctly? 
    You are dead right. The coffee still tasted great for me, I was just curious when I noticed it occurring.

    Cheers

    Leave a comment:


  • Fresh_Coffee
    replied
    Re: Early dark drops - Why?

    If you end up with a great crema and coffee, why does anything need to be wrong or have been caused by something you felt may not have been done correctly? 

    Leave a comment:


  • Yash
    replied
    Re: Early dark drops - Why?

    artman,

    Yeah Im very careful with my technique as well.  I would hope it was something as shameful as poor distribution 

    One thing I was doing around that time was slightly over-dosing.  I have ridged baskets and the optimum coffee level my machine is just below the ridge.  I used to often dose into the ridge and this would often cause a pit to form on the edge of the puck (Im guess from excessive pressure). Perhaps it was related to this...

    Leave a comment:


  • artman
    replied
    Re: Early dark drops - Why?

    I wouldnt say so in my case, I have been very consistent with my technique, and noticed them one day, then after a while noticed them gone. In hind sight, didnt think to check if it was a particular bean type though, maybe that was it?

    Cheers

    Leave a comment:


  • Yash
    replied
    Re: Early dark drops - Why?

    Good to know artman. Definitely eliminates the water in the handle explanation.

    These dark drops must be produced while the coffee bed is being settled and pressurized, perhaps caused by poor distribution?

    Leave a comment:


  • artman
    replied
    Re: Early dark drops - Why?

    My machine always needs a cooling flush, I backflush after each session, and I am using a naked handle, the cause wouldnt be "dirt" in my case.

    Cheers

    Leave a comment:


  • Yash
    replied
    Re: Early dark drops - Why?

    Hi askthecoffeeguy,

    Thanks for all the advice. Do you mean flush out stuff from the group handle (i.e. the area under the basket) or in the group head itself (i.e. above the shower screen)?
    I always do a clean-out/cooling flush before pulling a shot. Generally Ill do this without the handle attached. Not sure about my friend.

    Thanks

    Leave a comment:

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