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Bitter coffee can come from:
• Water that is too hot
• Coffee that is over-roasted or stale
• Cheap, low-quality coffee
• Worn burrs or low-quality grinder that makes too much dust
• Brew pressure that is too high
• Not using enough coffee in the portalter.
Sour tastes can come from:
• Brewing temperature that is too cold
• Coffee that is under roasted
• Brew pressure that is too low
• Bad or spoiled coffee
11. Cleaning and Maintenance
As with all fine tools, Vibiemme Domobar espresso machines can give you years of trouble-free service
and better performance if properly maintained. Your Vibiemme Domobar espresso machines does require
a bit of care, but it is not at all difficult.
Although the following guidelines will give you some idea of how often the tasks should be performed,
there is no specific set of rules concerning the frequency of cleaning and maintenance. A machine that is
being used to make two or three drinks each day in a home environment will not need to be cleaned quite
as often as a machine used in an office or restaurant where it is called upon to make fifty drinks a day. If
in doubt, it is better to do cleaning and maintenance chores a little too often than not often enough.
11.1. After Each Pull
KNOCK PUCK After the pull the spent coffee puck in the Portafilter should be knocked out. The best
way is to use a knock box. These feature a cushioned bar with a soft surface that protects the Portafilter
from damage.
QUICK FLUSH As soon as you remove the Portafilter from the Grouphead after a pull, cycle the brew
function for about one second or so. This will help flush out any coffee on or behind the shower screen.
FLUSH PORTAFILTER If you are not immediately going to pull another shot, replace the Portafilter
and repeat the quick flush. Pushing a bit of clean water through the Portafilter will remove most of the
left-over coffee in the Portafilter. Remove and wipe it off after the flush. If the machine is going to be
left on, leave the Portafilter in place so that it can remain warm.
AFTER EACH STRETCHING OF MILK The steam wand must be wiped off immediately after every use
with a damp towel or dish rag after removing the wand from the milk. As soon as the wand is wiped, the
steam valve should be briefly opened and closed to create a blast of steam to force out the remaining
milk that may be in the wand. Allowing milk to sit on (or in) the wand will cause the milk to bake onto the
hot metal. This is not only unsanitary but can also become very difficult to remove. If you do have baked
on milk we do not recommend soaking the wand in a pitcher. This can cause dirty water to be drawn into
the wand, and under certain conditions, possibly into the boiler.
