By Arno Holschuch, Bellwether Coffee
You can spot the copper ones from a block away. Their brilliant hammered bare-metal fairing and the proud La San Marco lion logo stick out like a bird of paradise among today’s minimalist café designs. If you see one, stop by and check in, because with a lot of tech support (and the hands of good barista), no machine yet made can beat the 1970s-era La San Marco Leva 80 lever espresso machines for shot quality. Lighter coffees that might be a little tart or unbalanced in a pump-driven machine come across as sweet and smooth; darker coffees that might taste muddy deliver big-boned milk chocolate. With the amount of R&D and design innovation that’s gone into brewing equipment over the past four decades, that’s kind of amazing. It’s like an old sports car that requires a tune up every hundred miles but can still blow the doors off a new BMW.
First, the basics: It’s a very simple heat exchanger architecture. There’s literally a copper tube that leads in through the wall of the boiler to a heat exchanger that looks like a six-inch sub sandwich. No fancy mixing chambers here; water in from the wall just pushes water out to the group when the valve’s opened. It features the classic “joystick” La San Marco steam handles. The hydraulics are pretty much all braised copper tube. And like an old car, there’s plenty of room to see what’s going on and fix it. It’s very simple in there.
All except for the group, that is. This is where the genius of La San Marco’s design really shines. Everything is different about this group.
To explain we should start with the way everyone else does this. In the “Futurmat” lever group (used by every manufacturer from Astoria to Kees van der Westen), the user pulls on a lever, compressing a single spring to raise the piston. This pulls the piston seals (known as “chevron gaskets”) up above that a passageway is allows water from the boiler or heat exchanger to jet into the side of the cylinder and preinfuse, or sometimes “pre-channel,” the puck. Release the lever, and that piston is driven home by the spring, pushing water through the puck. Levers all tend to make good espresso; common wisdom holds that it is due to the “pressure curve.” As the shot progresses, less water pressure is applied to the puck, as the springs that provide the pressure are closer to their totally relaxed length. Think about it this way – if you compress and spring until the coils are all touching, it’s going to push back as hard as it can. If you let it extend all the way, it will not push at all. Between those two is the springs' “pressure curve.”
In the La San Marco, the lever compresses two springs. Two springs means more brewing pressure – I’ve measured brewing pressures of 12 bars on these using a gauge at the group. The action of the lever also starts opening a valve to allow the water onto the puck. This valve is really at the heart of the group: using the same guts as their steam valve, they have implemented excellent, very soft pre-infusion. Just as steam valves can be opened gradually, this infusion valve gently lets water down onto the puck. And because the water isn’t being injected from the side, it’s more likely to allow for an even extraction of the puck.
One last note on La San Marco madness: They chose a 54.5mm diameter basket for their portafilter, making a narrower, deeper espresso puck. I am not going to claim to know why, but this puck shape seems to be part of the recipe for the sweet, mellow espresso it produces.
Now for the bad news. Like the old car analogy above, these machines are incredibly maintenance-hungry. The infusion valve needs regular rebuilding, and you need to have superhuman hand strength to compress a spring to get it all back together. The expansion valves need regular tuning. The dispersion screens have a nasty habit of popping out during service. The braised joints in the hydraulic circuit are delicate, particularly on the sight-glass assembly. And as with all lever machines, there are legitimate safety concerns – if you got in the way of that spring-loaded lever, a black eye is the best-case scenario.
But for all that, the lasting impression a Leva 80 makes is majesty. What the engineers at La San Marco created with a little brass, steel, and rubber wouldn’t be matched until the advent of modern closed-loop electronic pressure profiling systems like the Strada EP. The eye-catching beauty of the fairing has yet to be paralleled. They are a true artisan’s tool; they require excellent baristas to produce excellent shots, and a dedicated, dexterous tech to keep them in good working order.