A modern technique inspired by pour-over bloom — wet the puck, fully pause, let CO2 escape, then extract. Popularized in the Decent Espresso community.
The Blooming Espresso technique is borrowed directly from pour-over brewing, where it's standard to wet the ground coffee with a small amount of water and wait 30 seconds before continuing — letting trapped CO2 escape from the grounds and producing a more even extraction.
The espresso adaptation was developed primarily in the Decent Espresso community (John Buckman's company that builds the DE1 with its advanced profile software). The idea: when making espresso from very fresh coffee (within 1-3 weeks post-roast), the puck contains a lot of CO2 that pushes back against the water during extraction. The result: channeling — uneven flow paths that produce unbalanced cups.
The solution: instead of continuous pre-infusion, the method splits brewing into four distinct phases:
1. Wet (0-5 seconds): low flow saturates the puck. Pressure starts building up to ~4 bar. The puck gets exactly enough water to wet through.
2. Bloom / Dwell (5-30 seconds): the machine fully pauses — no water flow, pressure drops gradually to 0. Over 25 seconds the puck 'breathes': CO2 escapes, the grounds expand and form a more uniform surface. This is the defining stage of the profile.
3. Extraction (30-50 seconds): the machine ramps pressure to 9 bar quickly. First drop appears around the 33-second mark. Extraction happens at constant pressure for about 17 seconds.
4. Decline (50-55 seconds): gradual pressure decline to prevent over-extraction at the end.
The advantage: cleaner cups, consistent sweetness throughout, and dramatically reduced channeling that plagues espresso made from fresh coffee. The downside: requires a profile-capable machine (Decent, Slayer with certain firmware), and it's relatively long — 55 seconds instead of 30.
Many modern baristas working with fresh specialty coffee argue this is the only profile that successfully extracts new coffees without off-flavors.