Mail Bag

[HB]

The term "lurkers" refers to those who prefer to read online bulletin boards but never post. Occasionally one of these invisible fans writes me to ask for advice. I encourage them to share their query in the forum, but usually they beg off, citing either lack of time or disinterest in public exchanges. With the permission of the writer, I am posting a few of these notes to give you an idea of the offline questions I receive with the off-chance you might have the same idea / problem.

[HB]

Hi Dan,

After reading many reviews on CG and your buyer's guide, I purchased the Andreja Premium a few months ago. I've been a bit disappointed with the temperature stability and have been getting quite sour shots with a lightly roasted espresso blend (full city roast I think). I hope you don't mind me e-mailing.

My problem seems to be maintaining temperatures at around 206 to 209 F. I've done a lot of tests with a thermocouple in the PF. The tests show that a flush of more than 2 or 3 seconds means that the temperature in the last half of the shot decreases dramatically. With longer flushes I can get the right starting temperature (and hump) by adjusting the recovery time, but can't seem to find a way to achieve stability in the last half of the shot. As a result, I get sour shots with the lighter roasted espresso blends (which I like the best).

The only way I have managed to get consistent temperatures throughout the shot at around 206 to 209 is to have long idle times (i.e. 12 minutes) followed by a short flush of 2 seconds and a long recovery of about 55 second. With the Pstat ranging from 1.3-1.4 this gets the temperature to peak at 208 and drop to only about 206. However, even this quite long procedure eventually results in a general cooling of the HX after a few shots requiring extended idle times to maintain shot temperature.

I have two theories as to why I get this problem: 1) my machine is defective; or 2) the Andreja's vertifical HX construction. The vertical HX would explain why 2 second flushes seem to work for me, as only the first 10 to 15 mls of the HX would be overheated. In contrast, I imagine that if I had a horizontal HX machine, then all of the HX would be overheated, and a much greater flush required.

I'm wondering whether you encountered anything like this during your testing of the Andreja?

I have never tried brewing at such a high temperature, so I cannot speak from experience (highest I brew is 204F, which Andreja does without problem). I've never heard of anyone brewing anything about 206F (Malabar Gold). Keep in mind that the HX water is a mixture of the idle water and incoming water, which is at room temperature. Depending on the mixing of these two, there is a natural limit to the brew temperature. Also the thermosyphon plays a role, since it only has so much efficiency. For example, if the group idles at ~195F (which is typical), it will be very difficult to brew at 209F no matter how much flushing you do (i.e., the flush warms the group and cools the HX at the same time).

Frankly I don't know that a stock Andreja is designed to put out the extreme temperatures you describe. You could add an HX preheat coil, which would increase the inlet temperature considerably, or modify the thermosyphon loop (I haven't tried it, but as an example, I would expect that heavily insulating the TOP line would effectively raise the temperature of the grouphead because of the higher differential). Shortening the HX injector would also raise the natural setpoint, but again, I've never tried it, I'm speaking only hypothetically.

Dan,

Just thought I'd let you know that I solved my problem. It's quite embarrassing actually - my grinder burrs were blunt! This meant I had excessive fine particles giving sour shots. After this revelation, I switched to my old Rocky grinder and the sourness disappeared. I had bought the new grinder (Mazzer Super Jolly) second hand from a cafe - figures!

Thanks for you help anyway.

[HB]

Dan,

Re. your thread on HB for tamper specs starting with your own initial list, the following.

The way you are approaching this seems like you are collecting functional design parameters... I can give you a few but they would be meaningless outside the context I use them in, to a certain extent.

My context - I have three tampers.

a- a cheap Italian spring-loaded one I got as a present with my grinder - anodised aluminium hollow handle, steel mechanism and steel base covered in ABS;
b- Schomer's bare aluminium handle/convex base tamper;
c- Reg Barber's anodised aluminium handle with flat stainless steel base.

My context - my technique & history.

I started with a-, however it was too small in diameter and I suffered from (side) channeling a lot with it. Also, the mechanism does not allow to rotate the tamper whilst a force is being applied - essentially the base/stem rotate freely in the handle. Next I bought b- and c- and initially used RB's c- since it has better ergonomics.

After 10 months of practising with my Andreja Premium, of which the most part of the time I have been using the same coffee from Italy (imported from a small Roman roaster), I have evolved the following technique.

1- I use a- to even out the ground in the basket, just rotating it - the ABS has much more friction with the coffee and takes it along, so a careful rotation is enough to level and have an even distribution, I guess top to bottom through the layers of coffee. I finish a- knocking the side of the portafilter. This is faster than N-S-E-W finger levelling.
2- Next I give a quick 180 degrees tamp with c- at about 30 lbs or so reference force.
3- I finish off with b-, again at about 30 lbs force.

The 2- 3- combination may provide a different packing profile across the diameter than flat or convex only - and I think it works very well for me. Another observation is the surface structure.

The stainless steel bottom is very smooth and gives a different surface to the packing process and the packed coffee than the aluminium or ABS surface. Between the ground and the aluminium base seems to be more friction and as a consequence the surface looks smoother. With many variables involved this seems over the top - I guess you would need Versalab-precision tools to be sure about my approach to be detectably different, taste-wise. However, this technique gives me extreme consistency and a very low chance of (side) channeling.

Also, I presume a degrading pressure profile radially from the center of the shower screen to the edge - again, may not be detectable taste-wise.

My grinder is doser-less and I grind into a small cylindrical glass about 58 mm diameter. I use simple (electronic) scales to weigh 17.4 grams of coffee - the optimum for this type of coffee and my technique. While I flush my machine, I "dose" and grind. Next, take off portafilter, wipe dry basket, pour over ground, tamp, put PF back into machine. The whole process takes about 15 seconds.

Conclusion

For me, there would be a market for a 58mm ABS base, at least for levelling and evening out. Also, I have wondered if it would be possible to have a stainless steel base with radial polishing pattern. The disadvantage of aluminium is its initially polished surface looses its smoothness quickly - acids in coffee, etc., probably. However, the (sub?) microscopic roughness this introduces may be a blessing in disguise, in the light of the previous.

So, I would prefer a stainless steel base with the property of the aluminium to have more friction between it and the coffee.

Keep up the good work.

Best regards,

Peter in the Netherlands

Peter,

Wow, you've given this some serious thought! I'm copying DaveW from espressoparts and suggest you post your note below on the forum for others to comment on.

[HB]

Dan,

Thanks/OK.

I would not have time to frequent HB and register. If you want to, you can put my text on it, provided you remove my personal data. You could do something like: I received this email from Peter in the Netherlands, or Peter in Europe, and put the body of my email in it.

One thing that would add great value to HB is a discussion of flaws and faults and how to recognize them.

I guess photos would add a lot, however with many photographic variables involved, it would be very wise to include a reference grey/color card (graphics adapters, video cards and environmental light, etc. - so many variables influence perception whereas such reference would help greatly).

Side and top photographs of shot glasses... And, coffee 'puck' analyses: like in one piece, broken, layered, etc. Both will give clues to under- and over-extraction, under- and over-temperature, etc. I guess a relation exists between temperature and puck coherence. Probably at too low a temperature, no or little oils will be released and the puck might still be wet and easily fall apart (if not too wet). However, when temperature gets too high it may be that all oils are extracted and the puck would be dry and easily break up in layers that still have some coherence.

And then you could still have under-/over-extracted (too short/long or too much/little coffee) with all other variables OK. Whatever - just a few reflections without any underlying research. Why bother? It helps in the learning process and in getting the next shot better. In this respect it would be nice to try and make bad espressi on purpose, hopefully with deviating variables well known and documented.

Another thing I noticed in using Andreja Premium (AP) that is probably universal to E/61 groups is it is very difficult to get a really great espresso from the first shot in the morning.

a- It seems the first flushing ritual in the day after the machine had cooled down has a different temperature cooling profile. (My AP is on a timer.)
b- Next, it seems very easy to get a really great espresso from the first and consequent cups of espresso later on the day after the machine has been idle for considerable time.
c- However, after, say, half an hour idle it seems difficult again.

The former (a-) I attribute to overnight cooling and probably more air getting into the group head than in case b-. In case b- it seems the stalling of water flow is much more recognizable than in case a- and c-. I have seen a graph on the web of flush time as a function of idle time - my first impression was the graph is workable, at present I am in doubt.

Another thing just entered my mind. I think it was one of your own postings (it would take some time to locate it again) that told a travel story with a few pictures.

One of the photos held a toy cabriolet car of which you wrote you lost it later on the trip - assuming you were not aware of it and wanted to try to give your child one exactly like that: it was an Alpha Romeo "Spider" (from the most recent design series), however when you are into Italian coffee your way, I actually should assume you know this.

Peter in the Netherlands

This is the photo Peter mentioned:

This photo was taken at Cafe Marly in the Louvre while visiting Paris with my oldest son several years ago. We had just come from a toy store near Rue Rivoli where we purchased the car shown below. I setup this composition on the spur of the moment. There are a lot of unplanned but interesting reflections. I especially like the tourist caught mid-stride in the background. The espresso was so-so but the gateau moelleux (not shown) was fabulous.


Cafe Marly composition (sadly the car was lost only days later)

[HB]

Hi Dan,

My wife wants an espresso maker. Something really nice but not too expensive (under $300, but preferably under $200). Can you make a recommendation?

Mitch

Mitch,

To be honest (and you're gonna think I'm crazy), I would skip the espresso machine and invest the whole lump sum in a top-end grinder like a Rocky Rancilio and a French press. No convinced? Take for instance my Dad's recent experience. I bought him what is an upper-entry level grinder instead of the blade grinder he's been using for years. Over and over again he's said how much a difference it's made. Problem is, to get the same effect for espresso is a lot lot more expensive.

That's my recommendation: Enjoy the greatly improved coffee from Rocky, then decide later if you want to invest in espresso gear.