Cafelat lever group piston seals

- maart 24, 2022

For a while I've used the special custom piston seals that LONDINIUM had available for their lever machines (currently / temporarily out of stock). These are fractionally wider than the standard seals and the inner lip is fractionally higher:

These custom seals are especially helpful in the first generation LONDINIUM which has pre-infusion at boiler pressure. In that configuration it's essential that when raising the lever, after the puck is fully saturated, the lowest seal when sliding down immediately 'spreads' its lips, pushing down on the air pocket and brew water with nothing 'slipping' upwards past the seal. Then all remaining spring pressure is available to initiate the espresso shot.

A friend who currently owns my first LONDINIUM has tried the blue silicone seals that Cafelat produces for a number of lever espresso machines:

https://www.bluestarcoffee.eu/cafelat-group-lever-gasket--kit-11890-p.asp

The same friend later reported that the piston had trouble moving up and down inside the group as the seals seemed to be 'grabby' and sticking to the inner wall of the group. He even had trouble pulling the piston out to check the seals and this only worked after he pushed the piston back in place and switched on the machine to try again on a hot group when the seals became more willing to give. Using a different type of PTFE grease than the one he was used to, the sliding was more smooth.

Curious, I ordered a set of the seals and today I replaced the lowest regular seal with a Cafelat version.

I did use the 'superlube' that was included in the shipment and the lever moves up and down smoothly here, for now.

Will update later if there is a change in behaviour.