Guido,
I am going to respond to a couple of your points now and will address the
others in about 12 hours (if I can keep to my schedule for the day.)
At the risk of being verbose again, please tolerate an introductory remark.
When I trained with two of the top professional baristas in the world ("top" as
measured by the guidelines and rules imposed by the industry associations and
demonstrated in public competitions) and when I subsequently interacted with
many other highly regarded baristas and with other coffee industry
professionals during my training as a judge and subsequent judging, I acquired
some principles that my experience has tended to reinforce as truths to live by
with regard to espresso. My suggestions below reflect these. I don't claim to
be self taught.
Yes, your steam boiler pressure should be raised to hover between 1.2 - 1.3.
You could jack it higher safely, but you are then screwing up the engineers'
design parameters. Don't! (Wait until you get everything stable and happy ...
and you know what the f you are doing.)
RE the frequent heat requests: Your B4 is a PID controlled brew boiler and
heats with constant short little jolts of current rather than an analog
controller that lets the temperature drop ~ 2 degrees below the target and then
jacks it with a long burst of power to 1.5 degrees above and lets it slowly
fall back to the trigger. The reason we all pushed Todd to get the PID from
the Spaniards was that it holds temperature in a tighter range, so the time
from last heat request becomes irrelevant.
Gauges are sometimes wrong. When they are horribly wrong, it will usually be
obvious. Let's assume that your gauges are reasonably accurate and go with
their data report until all else fails.
Different coffees and roasts may require slightly different treatment, but you
manage those with your excellent grinder as the primary lever ... hold all
other factors constant.
(Up dosing is acceptable and sometimes necessary in order to get the very best
from a particular roast or blend. This was the subject of vigorous debate
among professionals back about 12 years ago. The 14 gram spec for a double set
by the Italian government is a nice starting point. But today, the top shops
are often dosing closer to 20 grams and using a coarser grind setting.)
Baristas around the world generally agree that the best tasting results are
achieved at about 8.5 bar at the puck. Anything between 8 & 9 will produce
good results. You should go back to your previous pressure and then leave it
alone.
Many baristas can set all of their gauge measurable items to the right level
and still get poor results because they get Channeling. I have never heard of
channeling attributable to an espresso machine's performance as long as its
pressure profile is within normal ranges (Love those OPVs)
Channeling is usually attributable to poor grinder performance, distribution or
incorrect tamp. I do not recall your mention of what grinder you are using,
but the reason good grinders are so expensive (and the reason competitors often
bring their own grinder to competitions) is that uniformity of grind is an
essential element of a good puck. Your frequent experience of channeling is a
variable we need to change. It is why I asked you to pull with a naked PF and
why Ben gently raised the suggestion that you work on the Weiss technique. If
you can not eliminate it, all the tinkering in the world with your machine will
not get you consistently good espresso.
On a related note, one of the reasons that the Gaggia is so nice is that it is
designed from the start to be as idiot-proof as possible. (I find myself
thinking of it as analogous to spears which were the principle weapon of
medieval armies despite movies today ... They took less training to use than a
bow or a sword. The Expobar is a rapier.)
I will address the basket issue later, but it is important.
Sent from my iPad
On Mar 25, 2012, at 4:01 AM, guido <[email protected]> wrote:
> hello kitt,
>
> here my reply to the first of your mails, the other will follow later.
>
>> Pressure against a blank,
>
> i've tried different settings, haven't settled definite yet, it was just a
> notch above 9, say 9.2. i have set it to 9.5 now, but this might be too high,
> i'm not sure here. the previous setting ramped up to 9 bar (with coffee) and
> the dropped to 8.5 as soon as the espresso has started to flow properly.
>
> in the beginning, it was set much higher. that was not good. i've gone a bit
> lower than i am at now, but that did not help. i've been testing as low as 8
> bar with coffee, measured after the drop following the ramp up. i don't think
> i should go lower, unless the gauge is giving faulty readings. i suppose
> that's not very likely the case.
>
>> Temperature after a four oz flush and five second pause,
>
> i can't measure with a styrofoam cup, i don't have one but will try to find
> it. for the display reading, it does not seem to matter much whether 4oz is
> pulled or not. it just behaves the same as when i hadn't pulled the shot,
> this time it stayed where it was, at 94.
>
> what i should mention, however, is that the 'heating request' dot is always
> flashing, idle or not, in an interval of estimated about 1.5 seconds. it
> takes all too often (but certainly not always) more than a minute to get back
> to normal after an 1 degree celsius drop, even if the steam boiler is not
> requesting heat.
>
> these drop occur rather often. i would estimate that the display shows the
> requested temperature value for about 3/5 of the time, 2/5 of the time it is
> lower than it should be. it seems to be always requesting heat.
>
> is all this normal?
>
> and what do you make of the steam boiler pressure, it gets never above 1 bar.
> when it heats up it stops around 0.95 bar. i read that i should be 1.2 bar.
> it has never been 1.2 bar. could this bear a relation to the difficulty to
> get to the right temperature of the brew boiler, as these two are linked? or
> in any other way contribute to the problems i'm having? that's just a thought
> that has occurred to me.
>
> is there a way to adjust the steam boiler pressure?
>
>> Shot pour time,
>
> variable, haven't set for anything yet, see my mail from yesterday about the
> very long pre-infusion time vs flow rate. what do you think of this theory?
>
> when i started, i aimed for about 27 seconds. i've experimented with longer
> times, up to 35 seconds. i'm still on the fence on what works best. when i'm
> not experimenting, i still aim for 27 seconds.
>
>> Basket used.
>
> both the standard brewtus basket and one that's exactly the same (shape,hole
> density/size), but slightly smaller. with the standard basket, i think the
> amount of coffee that worked best was around 15 or 16 grams, not entirely
> sure (my memory fails me) and the smaller one just a little over 14 grams
> (this does depend on the coffee, and the roast type in particular.)
>
> same faults with either basket.
>
>> Presence of channeling
>
> when i started with this machine, a LOT. really, just an awful lot. i have
> worked and worked to reduce this. got a new tamper, started to do the wdt,
> methodically tuned the fineness of the grind vs the amount of coffee.
>
> i have been able to reduce it a great deal, but not completely.
>
> i have to admit, the problem i have do taste similar to over-extraction or
> channeling. but i wouldn't know what to do about it anymore than i already
> did. i've read all i could find on the subject of channeling, tried every
> suggestion i could find.
>
> if there's still channeling going on, and this is the cause of my problems, i
> wonder what is causing this problem. i don't think this would be normal.
>
>> BTW ... Have you confirmed that the water from each boiler is untainted. I
>> had that problem once.
>
> i have tasted the water. before, it tasted fine. in time, it has gotten some
> *very* subtle tarry accents. i have cleaned the grouphead (taken the shower
> screen off.) i clean the showerscreen and it's sides after every shot. i do
> backflushes regularly, once in a while with a cleaner made for this purpose.
>
>> I will confess that I am extremely uncomfortable with three of your data
>> reports:
>> Baskets
>> Channeling
>> Verification of data accuracy
>
> what did you mean with the third part, 'verification of data accuracy'?
>
>> First, the change in baskets makes me uncomfortable. There is
>> nothingsacred about the Expobar filter basket, but using something "smaller"
>> is a little unnerving.
>
> why is that?
>
> the problem is exactly the same with the bigger basket in any case. no
> difference at all.
>
>> I use all Gaggia baskets because I dose directly into the filter
>> basket and tamp before inserting into the portafilter. I do not want the
>> snap of the Expobar basket passing by the retainer ring. That is just my
>> particular choice, it gives me more confidence that one more variable is
>> probably consistent from shot to shot.
>
> i dose directly into the baskets, too, leave the portafilter into the
> machine. i have removed the retainer ring to avoid the snapping. this
> couldn't be causing any trouble, could it? (i have to look at every
> possibility now, every little detail)
>
>> How do you determine the weight of your quantity of coffee in the basket?
> > ( I weigh every dose.)
>
> just the basket on my scale (a very accurate one) zero it and then weight the
> full basket. i always work with the exact same amount for the same batch of
> coffee, unless i'm trying something out of course.
>
>> What is the color of the shot ... Is it the same for both the Gaggia and the
>> Expobar?
>
> yes, getting the right shot color is easy. but sometimes with the brewtus, i
> see a drop of that all-too-blonde crema in the further fine colored cup. i
> assume this is a sign that channeling has occured. i never noticed that with
> the gaggia, by the way, and it's not always there with the brewtus.
>
>> Have you measured the water temperature of the pour ... Do you have a Scace ?
>> do you use the Styrofoam cup technique?
>
> i have neither, but i will find a styrofoam cup sooner or later. there aren't
> very commonly used where i live, haven't found a place to buy them unless i
> get thousand pieces.
>
>> The fact that you can not reproduce the results of your Gaggia unit,
>> even though you are using the same roast, the same filter basket, the
>> same tamp, and have no channeling is disturbing.
>
> i agree. very disturbing. it took me a little while to really admit it to
> myself that the gaggia works much better than the brewtus, even after all the
> effort i have been putting in. months of work, and the first shots i made on
> the gaggia were already better than anything on the brewtus so far.
>
> that's why i called for help. this needs to be resolved, it just can't be.
>
> i want to thank you again for caring. i appreciate it a lot.
>
> all the best,
> guido.
>
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