I just picked up this machine and I have been pulling some of the worst shots known to man. My grinder is an Ascaso Steel i-2.

I've gone so far as to measure beans to 16g of both Intelligentsia Black Cat and Stumptown Hair Bender, tamp on a bathroom scale to 30-32lbs, and I'm using an electronic timer into a measured/marked Bodem shot glass. I can consistently pull 1.5-2oz shots in 26-29 seconds.

However, I've never pulled a shot that didn't blond later than maybe 12 seconds into the pull (4-5 seconds after beverage started to come out of the portafilter) and I've never tasted anything so sour in my life.

Now, this lead me to believe that the temp is the issue. I've tried a number of ways of warming up the machine.

I've measured temp both with a styrofoam cup and water straight from the brew head and through a warm portafilter into the insulated Bodum glass that was pre-heated with water from the other boiler.

The highest measured temperature was 180F with most water at 172-175.

I've contacted the place where I bought the machine (a well known purveyor of "gear"), and they are telling me that 180F is perfectly acceptable out of this machine, and rather normal for a machine that isn't "Professional" (which *is* in the name of the machine, but I know what they mean, it's no GS/3).

I tend to think that I'll never get a decent shot out of any machine at 180F and that they are trying to pull a fast one on me. I'm supposed to call back Monday to talk to their tech who is most familiar with this machine.

Thoughts?

RobotDeathSquad wrote:However, I've never pulled a shot that didn't blond later than maybe 12 seconds into the pull (4-5 seconds after beverage started to come out of the portafilter) and I've never tasted anything so sour in my life. Now, this lead me to believe that the temp is the issue.

Blonding in 8 seconds? Sure sounds like channeling to me. Here's my recommendations, recycled from one of my recent posts:

• Study the Home Barista's Guide to Espresso (or Randy's EASY GUIDE),
• Get a bottomless portafilter and read Perfecting the Naked Extraction,
• Get an accurate scale (0.1 gram) and weigh your doses,
• Practice the WDT,
• Employ the Stockfleths Move for Dummies.

BTW, the styrofoam cup temperatures you report are not wildly out of whack, though they do sound a bit low. But the first step is to get reasonable extraction times. A pour lasting 26-29 seconds as you report should not blond sooner than 20 seconds. See When did this espresso extraction go blond? for discussion.

Also high brew pressure in excess of 9 bars, say 12 or more, will cause early blonding and "sharp" tasting espresso.

I have heard steam come out of the "blow off tube" (no idea what this is actually called) *while* pulling a shot, not just after I turn off extraction. Could this be indicative of too much pressure? Could too much pressure be caused by a new pump and go away as it's used?

Like tekomino said, brew pressure too high will blonde anything...
if you are discharging pressure back into the tank while brewing, you are activating the pump over-pressure valve.
sounds like your brew pressure is definitely too high. if it blondes right around ten seconds, thats when the pump is creating the most pressure... it builds and builds, discharges a bit (maybe) and finally busts through the puck somewhere, giving you a blonde shot.



im not certain if you can adjust the opv on the Ascaso.

I'd reduce the tamp or coarsen the grind.

jbell wrote:sounds like your brew pressure is definitely too high... im not certain if you can adjust the opv on the Ascaso. I'd reduce the tamp or coarsen the grind.

The FAQs and Favorites notes several discussions on OPVs under Vibratory pumps; in particular I draw readers' attention to I still don't get it: Why adjust the OPV, specifically the comments below:

another_jim wrote:You can adjust your grind and tamp to pull a 9 to 10 bar double; but for singles and ristrettos, you can't. The Italian spec for vibe pumps is to set it to 11 bar on a blind filter. If you can see the pressure during a shot, adjust it while pulling a single or ristretto, so you get 9 to 10 bar.

HB wrote:If you do some calculations to determine the flow rate / pressure intersection for the vibe pump, you'll find that it conveniently works out to around 9 bar -- if you're pulling doubles. As Jim notes, an OPV acts as a "safe release" for ristrettos where the pressure would otherwise rise to 10+ bar given the slower flow.

For even more details, see purpose of adjusting OPV?

For less experienced baristas, lowering the brew pressure increases the margin of error. While that's not a bad short-term solution, the better solution is correcting the technique errors through practice and extraction diagnosis via a bottomless portafilter.

As for the tamp, I put it near the bottom rung of probable causes. Even newbie baristas master the basics of tamping in short order; keep it consistent, level, and move on. The only tamping technique I've found makes a significant difference is nutating, though I hesitate to recommend it to new baristas since it will make a bad pour disastrously worse if done incorrectly.

RobotDeathSquad wrote:The highest measured temperature was 180F with most water at 172-175.

The basic rule of thumb on machines that allow you to adjust brew temperature is to lower the temperature if the shot is bitter and to raise the temperature if it is sour.

Black cat prefers cooler temperatures around 195 degrees F. Most espresso blends recommend around 200 degrees.

It sounds like your machine 175 - 180 is much too cold to pull good espresso.

How long do you let the machine pre-heat before you pull shots?
I would guess that since you have tried a lot of variations, that you pre-heat at least 30 minutes. Try an hour. If it is still too cold, return the machine.

Right, this is precisely my question. If the water that comes out of the dispersion screen directly into a foam cup is 172F, how could I ever pull a decent shot? Isn't the 195F they suggest the temperature of the water coming out of the brew head?

If I let the machine warm up for 1+ hours, I can get 180F (maybe 182F tops), but if I only give it 20-30 minutes it's 172-175F.

I thought that usually home machines like this (and the Silvia and the Gaggia Classic) are usually too hot, and you have to temp surf them down? The place I bought the machine from tried to feed me a line like "Well, you're never going to get 200F water out of a home machine."

Without a standard means of measuring, it's difficult to judge whether your machine is running cold, though it sounds like it. Again, channeling produces the same taste defect and is more common among new home baristas than equipment failures. You reported an 8 second extraction before blonding, which I would fully expect to taste sour, thin, and generally disagreeable (e.g., wet cardboard), even if the brew temperature was ideal.

An easy test of your temperature theory is to turn on the steam button for 10-20 seconds prior to pulling a shot and tasting. That will push up the brew temperature in a hurry. Despite our frequent reliance on thermometers and whatnot, your own ability to taste is the ultimate measurement.

HB wrote:An easy test of your temperature theory is to turn on the steam button for 10-20 seconds prior to pulling a shot and tasting. That will push up the brew temperature in a hurry. Despite our frequent reliance on thermometers and whatnot, your own ability to taste is the ultimate measurement.

on a duo, the coffee boiler is single purpose. steam is from a thermoblock.
the temp is controlled by an electronic thermostat. sounds like yours is out of whack.
they're cheap. if it's under warranty- it's most likely free.