A blooming shot is a technique that consists of three distinct phases: pre-infusion, a long "bloom" period, and a subsequent flow profile.
The shot starts with pre-infusion at a very high flow rate until it reaches a specific pressure, typically between 4 and 5 bars.
Once the target pre-infusion pressure is met, water introduction stops, allowing the pressure to drop slowly. No new pressure is applied, and the coffee puck is allowed to "bloom" for 30 seconds. This is similar to the bloom phase used when brewing with a V60.
After the 30-second bloom, pressure is ramped up—ideally to around 9 bars. The espresso machine then executes a flat flow profile, causing the pressure to peak and then slowly decline.
The extended 30-second blooming phase helps dissolve more soluble compounds within the puck. It also leads to a more even extraction because the bottom of the puck becomes hotter and gains significantly more access to clean water than it would on a standard espresso machine.
The blooming espresso profile starts hot because it was created by Scott Rao, who prefers pour-over flavors and long extractions. Scott's profiles typically start around 94 to 98 degrees Celsius.
No, it is ultimately a matter of preference. Because different coffees extract differently, you should adjust and go with a lower starting temperature if that matches your taste preference.
Lightly roasted beans are inherently less soluble and do not give up their flavors or materials as easily to water as darker roasts do. To overcome this low solubility, light roasts require increased water contact. While a standard espresso typically flows at a rate of 1 to 2.5 ml per second, an Allongé pushes a much higher volume of 4 to 4.5 ml per second to continually flood the puck with fresh water. A Blooming profile accomplishes a similar goal by holding water on the puck and letting it sit without adding more pressure.
John states that the Allongé profile is significantly more difficult to dial in than the Blooming profile. Because the Allongé relies on incredibly fast flow rates, even minor, microscopic adjustments to the grind size will trigger massive, volatile differences in overall extraction pressure.
Yes, John explains that while Blooming is heavily optimized to open up light roasts, it also works very well for extracting medium roasts. However, he strongly advises against using a Blooming profile on dark roasts, as it would cause them to over-extract and turn overly bitter.
Some users struggle to pull smaller, single shots out of a 10-gram basket on the Decent machine. John explains that 15 grams is generally the most common and reliable dose used by customers. When utilizing a 58mm basket with low doses like 10 grams, the coffee bed layout becomes flat and thin, which causes it to lose structural integrity. Traditional 53mm baskets (which are half a centimeter narrower) provide a deeper, thicker coffee bed for smaller doses, allowing them to resist water pressure much more successfully. For those trying to use a 10-gram basket on a 58mm group head, John recommends lowering the machine's extraction pressure to compensate.