I’m seeing more shops flip to low-pressure preinfusion on their volumetrics — around 2 bar for 5–7 seconds — after recent firmware tweaks from a couple machine makers. I’m updating my extraction workshop this week and want to hear what you’re teaching bar teams about dialing with softer starts and how it’s changing puck prep and service speed.
We flipped our PB to a “2 bar for 6 s” preinfusion and now coach folks to grind a touch finer and tamp just to level — like easing the clutch instead of popping it. For speed, we shave about 5 s off the programmed shot time so total workflow stays even, but caveat: with super-dense light roasts we still keep full shot time or add a puck screen. If blonding creeps early, bump dose +0.2 g before chasing grind.
Agree with @victoria_s25 on the gentler tamp — one tweak that sped us up with 2 bar/6 s was adding a touch more headspace (drop dose about 0.3 g) so the puck won’t kiss the screen and stick after the prewet; on denser light roasts I keep the dose and shorten the prewet instead.
Small tweak that helped us: we recalibrated our volumetrics to bake in about 4 g of “soak loss” from the gentle start so a 36 g target lands in-cup without babysitting. @fred_smith1978 it sped service up, but ultra-fresh coffees need a smaller allowance.
Piggybacking on @emilyb27’s headspace point, we kept our 18 g recipe but swapped to a 20 g basket so the gentle preinfusion doesn’t kiss the screen; service stayed snappy and clarity went up. Small caveat: do a quick “sidewall sweep” with your WDT or you’ll get edge rivulets. Anyone else finding baskets an easier lever than dose?
Quick tip: with softer starts we add a thin puck screen so we can grind a hair finer without extra WDT; it steadies the ramp and kept service snappy, like giving the puck a tiny umbrella. @fred_smith1978 worth noting the screen retains about 1–2 g, so if you’re targeting a specific in-cup yield you’ll come up short unless you account for it.
With ‘2 bar for 5–7 seconds’, we bumped brew temp 1°C; keeps clarity, but darker roasts flatten.
But after flipping firmware, we found ‘2 bar for 5–7 seconds’ made our volumetrics under-pour by about 4 g because the flowmeter counts preinfusion water that doesn’t hit the cup, so we reprogrammed doses by weighing in-cup and nudged the target up until the ratio matched. Small caveat: on darker blends we cap PI at about 4 s during rush or they choke and slow service.
We ran into under-pours after adding soft prewet; @oliver_west21, turning on the firmware setting to exclude prewet from the flow count fixed it, and on older groups we just reprogrammed with a +3–4 g offset by weighing in-cup… > caveat: on darker blends we cap PI at about 4 s during rush or they choke Agree; we trim to about 4 s on our house blend during rush to keep flow predictable.