In general, extraction is the process by which hot water, inside the machine, passes through the ground and blends the coffee into the cup we all know.
The entire operation oscillates with a time frame ranging from 20 to 30 seconds. During this timing of espresso coffee delivery, the over- and under-extraction, can tell us many things about our coffee. When these times are too short, i.e. under 20 seconds, the under-extracted coffee appears less full-bodied than the classic espresso; the cream tends to dissolve and the taste is too light and not very aromatic. On the contrary, when the extraction operation exceeds 30 seconds, a coffee with a rather dark colour, excessively bitter and with little aroma is produced. The cream tends to be placed on the edge and has a hole in the centre.
Therefore we list some causes and solutions that can cause over-extraction, under-extraction, and other types of problems that do not allow us to obtain a perfect coffee. Starting from questions that we often receive:
1 -> possible causes MILLER
1.1-> MILLER solution
2-> possible causes MACHINE
2.1-> MACHINE solution
Why is there no coffee delivery?
2 - The filter may be clogged due to too fine grinding
2.1 - Clean the filter well. Grind the coffee again in a larger size.
Why does the coffee come out too quickly?
1 - Grinding coffee too coarse
1.2 - Grinding the coffee again at a smaller size
Why does coffee drip down?
1 - coffee grinding too fine / over-pressing coffee
1.2 - Grind the coffee to a larger size again / Reduce pressure when pressing the coffee
2 - clogged showers
2.1 - thoroughly clean the hand showers
Why is the cream too light?
1 - coffee grinding too coarse / weak coffee pressing / low dose of coffee in the filter
1.2 - Grind the coffee to a smaller size again / Increase pressure when pressing the coffee / Check the ground coffee spout for the correct dose of coffee.
2 - water temperature lower than 90° / pump pressure higher than 9 atmospheres / clogged showers / expansion of filter holes
2.1 - increase the temperature of the water, bringing it up to full capacity / decrease the pump pressure to 9 atmospheres / thoroughly clean the hand showers / replace the filters
Why is the coffee cream too dark?
1 - Robusta coffee blend / coffee grinder too fine / high dose of coffee in the filter / excessive coffee pressing
1.2 - this may be a voluntary choice in mixing. If not to your liking, replace the blend with a higher percentage of Arabica coffee / Grind the coffee to a larger size again / Check the grinder's spout for the correct amount of coffee / Reduce pressure when pressing the coffee
Why does coffee have so little cream?
1 - low dose of coffee / weak coffee pressing
1.2 - Check the ground coffee spout for the correct dose of coffee / Increase pressure when pressing coffee
Why does the coffee cream have a poor hold and lasts for a short time?
1 - wrong grinding
2 - water temperature higher than 90°
2.1 - decrease water temperature, bringing it to full capacity
Why are splashes coming out of the spout?
1 - old ground coffee
1.2 Remove the leftover ground coffee and replace with freshly ground coffee
2 - pump pressure less than 9 atmospheres
2.1 - increase the pump pressure to 9 atmospheres
Why do the spouts deliver differently?
2 - incorrect pressure / obstruction of the nozzles
2.1 - check the pump pressure up to 9 atmospheres / thoroughly clean the nozzles
Why is coffee dripping from the filter holder?
2 - the underbody seal is leaking / there may be coffee residue on the filter holder / the filter holder may have been inserted incorrectly
2.1 - replacing the underbody gasket / thoroughly clean the filter holder / release and insert the filter holder correctly
Why are coffee grounds left in the cup?
1 - grindstones may be consumed / coffee ground too fine
1.2 . check grinders for wear and tear and replace if necessary / regrind coffee to a larger size.
2 - expansion of filter holes / lack of cleaning between filter and filter holder
2.1 - replace the filter / disassemble and thoroughly clean the filter holder