The legendary long low-pressure pre-infusion ramping up to 9 bar. The Slayer machine's signature control style made this a specialty coffee standard.
The Slayer profile is one of the revolutions of modern espresso. It was developed by Marc Bunch and partners in Seattle in 2007 as part of the launch of the Slayer Espresso machine — the first commercial machine to allow precise manual control over the pre-infusion stage.
The real secret is the Needle Valve: contrary to popular belief, what makes a Slayer a Slayer isn't the paddle itself — it's the needle valve installed in the group head. This is a needle-style valve that physically restricts water flow to a very low rate (~1 ml/s) during pre-infusion, before water even reaches the puck. This allows you to saturate the puck gradually without building pressure — producing the long, distinctive Slayer pre-infusion.
The 2-click Paddle:
- Click 1: engages the machine through the needle valve. Water flows at the restricted rate (~1 ml/s) and pressure stays low (~0 bar). This is the long pre-infusion phase — typically 20-30 seconds.
- Click 2: bypasses the needle valve. Flow is released from its restriction, pressure jumps to a full 9 bar, and extraction begins in earnest.
The revolution: until then, all commercial espresso machines ran at a fixed 9 bar. Slayer let the operator choose a long pre-infusion that saturates the puck evenly before pressure ramps to 9 bar for extraction.
The result: more balanced cups, less bitterness, deeper sweetness, and a more refined aromatic profile. This pattern became the standard for modern specialty coffee — especially for light roasts that require slow extraction to develop properly.
On high-spec machines (La Marzocco Strada, Decent, Modbar) the Slayer profile can today be replicated through software pressure curves — but the classic remains the physical needle valve of a real Slayer machine.