How Lever and Spring Machines Pre-Infuse
On La Marzocco's Leva-X, the maker says holding the lever position controls the length of pre-infusion. Other lever machines may differ, so follow the manual for your model.
Where the word "pulling" comes from
The act of making espresso is often called "pulling" a shot, and Wikipedia says the term originates from lever espresso machines.1 A barista pulls down a handle attached to a spring-loaded piston. The piston forces the water through the coffee.
Two kinds of lever
Wikipedia lists two types of lever machine: manual piston and spring piston.2 In the manual type, the operator pushes the water through the grounds directly. In the spring type, the operator tensions a spring, and the spring then delivers the pressure. Wikipedia gives the usual spring-piston pressure as 8 to 10 bar.2 That's the main brew, not the soft start.
Holding the lever
La Marzocco's Leva-X is a mechanical machine with two levers. The maker says owners can adjust the spring preload to control peak brewing pressure, and can hold the lever position to control the length of pre-infusion.3
What this means for a newcomer
The saved sources describe this only for the Leva-X. Other lever machines may differ.
Wikipedia describes the two lever designs in general terms, but it says nothing about pre-infusion on lever machines.2 So this page can't tell you how a manual piston or any other spring machine handles a soft start. The only maker statement saved here is La Marzocco's, and it covers one model.3 If you own a different lever machine, its own manual is the place to look for anything about a soft start.
- Read the maker's manual for your model.
- Treat any pressure or timing figure you find online as a note about someone else's machine, not a rule for yours.
- Follow your own machine's manual for how to operate the lever.
Preload and the soft start are separate controls
Read the La Marzocco wording again. Preload is tied to peak brewing pressure. Lever position is tied to the length of pre-infusion.3 Two controls, two jobs. Changing one doesn't mean the other has moved, and the maker doesn't say they affect each other.
Also, the maker adds that the pressure profile is affected by the density and preparation of the puck.3 That's why two shots on the same lever machine can feel different.
One thing the sources don't say
Neither saved source gives a standard hold time for lever machines, so this page doesn't either. If your maker supplies one, it'll be in the manual or on its support page.
For how pump machines go about it, see pump machines. For the basic idea, see what pre-infusion is.
Notes and sources
- Espresso, Wikipedia
- Espresso machine, Wikipedia
- Pre-Brew, Pre-Infusion, and Pressure Manipulation Explained, La Marzocco USA
More soft-start notes
What Is Pre-Infusion in Espresso?What the gentle first stage of an espresso shot is, what it's meant to do to the coffee puck, and how makers describe it in their own words.
Pre-Infusion Versus BloomingPre-infusion and a pour-over bloom both wet the coffee first, but they aren't the same step. Here's how the two terms differ and where each is used.
How Pump Machines Pre-InfusePump espresso machines make a soft start by pausing the pump or by opening a valve to low pressure. Here's how three makers describe their versions.