Same thing as this whole thread is about....the off taste, which I think is bitter and ashy - maybe burnt..but I do not think my taste is trained enough to pinpoint it. I get the exact same "looking" shot every time, a nice even pour, very "gloopy" and thick, tons of crema etc. Everything "visually" looks great. Getting about 2oz in 25 seconds with 16-17 g of beans. Did the bottomless PF thing...and it seems to confirm a decent shot...no channeling...nice and even extraction across the entire basket...not too much early blonding etc. etc.

But, I have just noticed I am often getting a dark, oily ring on the espresso, which tastes like charcoal and is a nasty bitter. Seems to come through in the first few drops of the extraction. Adding milk, it seems to push this oil to the sides of the cup, where the first sip is quite awful. I have done cooling flushes up to 8 or 9 "mississippi" past where the hissing/bubbling stops and it still often appears....I thought this was an indication of too high a temperature.

I am not saying that the machine is malfunctioning (though maybe it is), but this is not rocket science either. So, I was just hoping to at least be able to confirm that I am in the ballpark for temperature, without going out to spends hundreds on a TC/Meter setup etc. If I can confirm temperature repeatability using a simple test, than at least I can move on from there. Does that not make sense?

Grant

Your brew temp is too high on those shots.
You need to flush longer.

At present - what is your boiler pressure at?

The boiler (but none of the tubing going in/out of the boiler) is insulated....in case that might a difference.

The boiler gauge cycles from about .95 to about 1.1 (just approaches 1.1..doesn't quite get there).

Grant

Grant wrote:..and if this will give me a close measurement, what should be the approximate temp in the cup to give me the needed temp in the basket?

Yes, if you hold the cup tightly against the group and pull the requisite amount, it will give you a ballpark estimate. Generally it runs cooler than the actual brew temperature because the water spends less time in the heat exchanger during an unrestricted pull.

Grant wrote:But, I have just noticed I am often getting a dark, oily ring on the espresso, which tastes like charcoal and is a nasty bitter. Seems to come through in the first few drops of the extraction.

I'm with Chris, you're over-temperature, I'll guess that you're allowing too much "rebound time." Overextraction is another possibility, but judging from your description of the bottomless portafilter, I doubt it. A video of the pull would confirm.

Grant wrote:The boiler (but none of the tubing going in/out of the boiler) is insulated....in case that might a difference. The boiler gauge cycles from about .95 to about 1.1 (just approaches 1.1..doesn't quite get there).

Sounds fine to me. Now let's back up for a moment and review...

Getting a good shot really isn't that complicated, and you don't need a thermocouple or even a thermometer. Consistency is the key, whether by intuition or measuring. There's different ways of assuring your consistency during the flush (volume, timing, observation).
I don't want to fuss with measuring cups or watching the clock, so I observe the flush and count off the temperature. The hissing and sputtering stops at 206F and the temperature drops one degree per second from there (look for "video clip"). Again, the key is consistency from shot-to-shot so you can adjust by taste.

You may find it easier to streamline your routine by removing the retainer clip from the portafilter so you can tamp the basket directly on the countertop. Specifically the routine I'm proposing is:

1. Fill and tamp the puck / basket,
2. Draw water for the cooling flush (e.g., end of sputtering + n seconds),
3. Remove the portafilter,
4. Drop in the basket,
5. Lock the portafilter back in,
6. Once 15-20 seconds has passed since step 2, pull the shot (adjust rebound time to taste).

(It's easier to assure the rebound time is consistent if you're not relying on your ability to fill and tamp in less than a minute). If you want to confirm the temperature using the Styrofoam cup and thermometer technique, keep in mind that is an "average" of the shot temperature, and the reading depends on the reaction time of your thermometer. That is, it's more for confirming consistency than targeting an absolute temperature.

AAARRRGH! Apparently it's my coffee causing me so much grief - not the machine (as you suspected), and not me or my technique (I am glad), and not the cooling flush/temperature either.

This weekend, I popped over to a local roaster here in St. Albert, and picked up a few pounds of beans. I tried some Mexican Organic Ismam, freshly out of the roaster...and I can do no wrong with it. It should be even better in a few days as I rest it. Makes an deliciously mellow and very low acid shot with anywhere from a 3-7 second flush past the water dance. A little too mellow for milk though.

Next, I tried their Organic Espresso blend, and while I found I would have liked it roasted a little less, again, no trace of that horrible bitter ashy taste I have been getting.

So, I now have to address this issue I think as a bean roasting (or bean quality) issue. Now that I have at least some baseline professionally roasted coffees to compare against, I can try roast some of their greens and compare results.

Thanks all for the support and help. I greatly appreciate it. I learned a lot about my Bric from dealing with this.

Grant

Was reading this thread for my own enlightenment. - I learn a lot that way.

I would still suggest you meter the screw on the showerhead. I think you'd be surprised as to the temp during the pull. Cost for some k-type fine wire is 5-10$ and an adequate meter cost me 17 incl shpg from Ontario. Ebay is your friend! See my link in my sig.

Grant wrote:AAARRRGH! Apparently it's my coffee causing me so much grief - not the machine (as you suspected), and not me or my technique (I am glad), and not the cooling flush/temperature either.

This weekend, I popped over to a local roaster here in St. Albert, and picked up a few pounds of beans. I tried some Mexican Organic Ismam, freshly out of the roaster...and I can do no wrong with it. It should be even better in a few days as I rest it. Makes an deliciously mellow and very low acid shot with anywhere from a 3-7 second flush past the water dance. A little too mellow for milk though.

Next, I tried their Organic Espresso blend, and while I found I would have liked it roasted a little less, again, no trace of that horrible bitter ashy taste I have been getting.

So, I now have to address this issue I think as a bean roasting (or bean quality) issue. Now that I have at least some baseline professionally roasted coffees to compare against, I can try roast some of their greens and compare results.

Thanks all for the support and help. I greatly appreciate it. I learned a lot about my Bric from dealing with this.

Grant

Wow...I am yet again humbled by the number of variables that go into a good espresso and how each one can individually effect things. After going through all the pain and suffering trying to resolve this temperature problem (that I never had other than some flushing problems), and then thinking I had resolved it by changing beans (a bean age or roasting problem), I have since come to realize that it has been the grinder causing the problem all along.

Here's how it has all come to play out thus far.....

At some point just before I got my new Bricoletta, maybe it was the excitement, I got lazy with cleaning my grinder. Backtrack 1 year.....ever since I got my Silvia and Rocky, I cleaned both religiously, including the Rocky every 2nd weekend....and my Rocky has sloppy Burrs, which I have now learned appears to cause some serious problems if not addressed. I never realized it before because as part of the re-assembly procedure, I always re-teflon tape the burrs to keep them nice and tight. Since I so regularly cleaned and taped the burrs...I never noticed any problem previous to the Bricoletta showing up.

Anyways....the new Bricoletta shows up, and soon afterwards, I started getting the horrible ashy, burnt or overextracted oily shot problem this whole thread started with. I immediately went to work trying to figure out temperature, flushing, etc. etc. A couple weeks of bad coffee and frustration. i.e. New machine...new problems...must be a machine usage problem...common sense right?

As time went on, I began to suspect something else (with Malachi's help), and when he suggested getting a "standard" well known bean to compare against, I started to suspect the home roast may be a problem. I then had the opportunity to get some from a local roaster, so picked up a batch. Here's where my stupidity kicked in. At the same time I started using the new beans, I had remembered I hadn't cleaned Rocky in a while, and cleaned and taped the burrs again. It's here when the problems all disappeared...great espresso again....but I wrote it off as the new coffee supply...not the grinder.

I have since gone back to the old beans as well....and they are all full of chocolately goodness that Silvia was so good at extracting. Anyways...last week, I also got some new roasted beans for the drip machine (I rarely ever use this), so I have been bouncing Rocky back and forth between drip and espresso settings...and the horrible ashy, burnt taste is back...without any other changes in coffee or technique. Then it dawned on me! I cleaned the grinder and re-taped the burrs, and like magic, the problem is gone again.

TA DA! Grinder problem....woo hoo...guess who's getting a new grinder as soon as I save up some play money!

Grant

Nice catch!

Grant wrote:The previous week of "playing" has resulted in a couple questions though....

1) How do you time the 2nd or 3rd shots if you are pulling multiple shots. For example this AM, I get up, prepare everything, pull the cooling flush (up to about 7 seconds now past water dance ending), and and then load and shoot. Then, I dump/clean the basket, re-load and tamp the basket...but then am unsure how long (if at all) I should flush for. If I manually start a flush, I do not see any water dance or hear any boiling/hissing, but am unsure if I should flush a couple ounces anyways? Time to clean the basket, re-load etc. is probably about 45 seconds - 1 minute past the end of the first shot.

This same question drove me crazy a while ago. By using the themometer in a styro cup technique, I found that my machine needed a substantial flush (8+ oz) to get to optimal brew temp. The first flush was easy to measure due to the hissing, but subsequent flushes did not exhibit the telltale signs of overheated water unless there was 5+ minutes between shots. Click the link in my sig below to see how I tapped and probed my grouphead. Now I can regulate my flushes to a precise temp, and even monitor brew temps in real time.