Hello everybody

I have found several existing threads on the subject but I thought it was better to open a new one since it is referring to a different coffee machine, a professional Fiorenzato Ducale, bought second hand.

I have been learning a lot of tecniques and theories about coffee and cappuccino and I have been trying to squeeze the most from my espresso machine.

I have another thread open here if you want to have a look.

I have been trying different grinder settings, different weights, different temperatures and pressure: the common issue is blonding. I have blonding after 12/15 seconds all the time. I also tried to overdose, still blonding.
I can see what I think are "tunnels" after the shot on the coffee puck but I didn't manage to get rid of them despite all my efforts.
The coffee is grinded fresh all the time, the dose is between 7 and 8gr (tried different doses), and I understand that tamping is very important. I think I am doing it correctly, trying to be as even a possible and tamping with 12 chilos.

I preflush the machine until it stops boiling, and the water pressure reads 8.5atm.

Everything else "works" as the "manual" says: I can have an over/underextracted coffee depending on dose, grind, time... but ALL the time after 15s I have the bloody "white button" on the cream, even though the cream looks like tiger fur.

I do not have tunnelling with 9gr of powder (that should be actually 10gr according to my scale, but a more exact one is on its way) and with 9grx2 I then overfill the double filter.

Here are some pictures
coffee puck after extraction with 9gr on the grinder (it should be actually 10gr)



Quantity of powder used


Tamped powder


Result, 15s.


According to the manual, I should make the powder coarser, but anyway I would have blonding after 15s anyway.

Here is with 7-8gr of powder


Anything I am missing?

Ok, next time I'll use my reflex

Thanks everybody!

Tony

But how does it taste?

Tamp is important, but not super important.
Grind, dose, distribution.

If I set the grinder for 25s extraction, it tastes burnt. It is much better in 15s, with a coarser powder, but then it's a "blondie"

What kind of coffee are you using?

First thoughts: How old is the coffee? I find most coffees start to loose their peak flavors about 3 weeks after roasting. Channeling and wet pucks usually means too fine of grind and yours does look powdery. I think everyone "fines up" the grind as the coffee ages in order to extract flavor but at some point you get wet pucks. So how old is your coffee? And are you getting the same results with different coffees and different roasts?

We are still trying coffees, we have been using the same type for a few weeks. The beans are bought and then used within days. Hopefully the beans are freshly roasted when I buy them.
The coffee is this one http://www.iow-espresso.co.uk/product.aspx?id=7

I adjusted the grinder looking at the extraction, trying to achieve the 25ml in 25s with good cream, no blonding etc etc but I always have blonding after 15s. Yes, the puck is usually very wet.

I am also concerned that the single filter we've got with the coffee machine is a bit too big. The grinder is now set for 9gr, and the powder fits confortably in the filter but two doses do NOT fit confortably in the double filter. I reckon the two filters are mismatched. Shall I get a 7gr filter to start setting some "known points" in the chain?

Single baskets can be difficult to work with. It sounds like you are using the doser on the grinder to meter your doses? If that is the case, don't. They are inaccurate, to get a reliable dose you will need a scale. After a few months you could do away with the scale when you have a hand on the dosing. Most double baskets will hold 12-18 grams of coffee. To make sure you are getting the proper headspace between the coffee puck and the shower screen you could try the nickel test. Was your grinder purchased new or used? If used did you replace the burrs? Stale coffee and/or worn burrs will do exactly as you describe. Massive channeling will also cause early blonding along with a bitter/watery cup. Fresh coffee is defined (to us) as roasted between 3 and 14 days ago.

I think Dave is on the right track here. You may not be using enough coffee or the coffee is past peak. This latter point is critical. Old coffee will rarely yield good results. I don't have a scale. I use a little 7 gram coffee spoon (2 scoops for a double.) But here is a way to get calibrated without doser or scale:

1. Get some freshly roasted high quality coffee. (Do you have anyone local?)
2. Set grinder in the "neutral" position so that the grind is a little finer than beach sand (not powdery)
3. Dose from the grinder till the portafilter has a nice conical mound (about 1 inch above the edge of the portafilter.)
4. Tap the portafilter till the grounds settle and then tamp at 30lbs. The portafilter should slip into the grouphead with clearance to the screen. (If you remove the portafilter and the coffee is disturbed then you have too much coffee. Go back to step 3, tap and then use your index finger to create a small concavity in the coffee and then tamp.)

There are lots of videos on HB that you can look at. But I would move away from dosing till you get good results. And coffee freshness is the most important factor since you can control everything else.

Thanks everybody.

The grinder is second hand and I haven't replaced the burrs. Looking at the coffee machine that was supposed to be "serviced" I guess that this could be the trick.

Unfortunately my business partner is a strong believer in "coffee machine should never be cleaned nor touched" and I was unsuccessfully in trying to explain him the very basics, including flushing the groups before the shots - no matter if I was showing him the temperatures with a precise thermocouple. I won't even try to mention him something more complex like burrs or weights, it would be pointless
A precise scale is on its way, I will check the weights later.

Thanks!!!

I suspect the coffee before anything else.

A cheap and easy thing to try would be to order some known fresh coffee, for example from http://www.hasbean.co.uk or http://www.squaremilecoffee.com (note: there are others, but I don't have time to find links!). This would be cheaper than replacing the burrs!