The coffee extraction depends largely on the coffee grind size and therefore on your coffee grinder settings.
The grinder’s blades wear and tear can affect the grind but less obvious and more often, the weather conditions is the main factor that affects the grind of the coffee and therefore, the extraction’s speed.
Coffee beans are highly sensitive to humidity. When the weather is hot and humid, the coffee beans absorb the humidity and they ‘sweat’, releasing their natural oils. The oilier coffee grinds tend to clump together making the extraction slower.
On the other hand, when the weather is dry, the coffee grinds remain dry and separate enabling a quicker flow of extraction.
Therefore, adjust your coffee grinder to coarser grinds when the humidity is high and finer on cool and dry weather conditions.
Test the extraction rate. The rule of thumb for the extraction rate is 1 ml per second. So, as a guide, it should take 28 to 30 seconds to pour a full espresso, using a double portafilter and dose size of no less than 18g of coffee.
If the coffee extraction is too fast, your grind calibration is too coarse. So, for most grinders, move the collar anticlockwise to bring the burrs closer together.
If the coffee extraction is too slow, move the collar clockwise to bring the burrs further apart. Remember little movements do big things.
After adjusting the grind, wait after three shots before making another adjustment because the dosing chamber may still have a small amount of coffee left from the last grind calibration. Check your extraction speed again and adjust accordingly.
To provide consistent perfect espresso to your customers, adjust your grinder to changing weather and temperature conditions not just once a day but all throughout the day.
Tip for remember in what direction to dial the grinder: