Vibiemme Domobar Junior - Manual (Page 13)

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7. The Espresso Speedometer
It’s time to actually make espresso! The coffee has been ground and tamped into the Portafilter, and
the Portafilter locked into place. All that is left to do is to place a cup under the spout(s) and switch the
machine into brewing mode (see Chapter 3 for details on how to operate the various models).
Espresso has speeds- more accurately, it has rates of flow while being created. When you switched the
machine to brew, the pump pushed fresh water into the brew boiler which displaced hot water and forced
the hot water through the Grouphead, through the coffee, and out of the Portafilter into your cup.
How it emerged, what it looks like, and hot fast it flows are all indications as to how well the previous
steps were performed.
How Much, How Fast?
There is a range of volume of espresso that should take a certain amount of time to be created. Whether
it is a double or single, the “pull” should be about 25 seconds. The term “Pull” comes from the original
espresso machines that were lever operated and the barista had to “pull” the lever to push the water
through the coffee.
As the espresso issues forth from the Portafilter spouts you will notice that some pulls issue forth too
slowly and other pulls it might flow much too fast. There is a “sweet spot” that is sometimes referred
to as the “Golden Rule of Espresso.” The general parameters that define this (for a double espresso) are
about two ounces of espresso in about 25 seconds. For a single it is about one ounce in the same amount
of time. We purposely state “about” because this is not so much a rule as it is just a guideline- a starting
point. It should be considered just a foundation from which to begin your espresso adventure.
As you get started, don’t get too caught up in timing and measuring. Excellent espresso can be made in
a range of about twenty to thirty-five seconds. A very tasty double can be as little as 1.25 ounces to as
much as 2.5 ounces. Think of these parameters as a bell curve with the greatest percentage of success
to be at the central peak of the curve.
Learning what various flow rates look like so that you can visually identify when things are working
as they should, as well as when they are not, is a good place to begin. Below you will learn how to
differentiate a good pull from bad as well learn solutions to most common problems.
Too fast
A flow of espresso that is issuing forth too quickly will lack viscosity- it is thin and watery. The color of the
stream is quite light in color which is a sign of under-extraction.
Causes of a fast, pale flow can include:
• Too coarse of a grind. Set your grinder to a finer grind. How much finer? It depends on the grinder itself.
As each brand works differently you will need to experiment to learn just how much to change the grind.
The faster the flow the further the grinder will need to be adjusted towards a finer setting.
• Channeling. This is usually caused either by improper distribution of the coffee before tamping or if the
coffee was dosed with voids in the mass of grounds. The force of the water can bypass much of the puck
and flow through without extracting properly.
• Under-dosing. There was not enough coffee in the basket and so there was not enough resistance to
the flow of water.
• Too much force in the flow. This can be caused by steam build up that was not properly bled before
pulling the shot. The blast of steam mixed with water disrupts the structure of the puck. This can also be
caused by a improperly adjusted overpressure relief valve.
• Faulty basket. If a basket develops a crack it can flex open under brew pressure and allow the puck to
be damaged causing a fast flow. If this is suspected, examine the area on the floor of the basket around
the outer perimeter of the perforations which is where most cracks occur.