Londinium profile

Londinium is a brand of coffee machine that hail from the UK.

They primarily focus on lever machines.

These machines have become famous for their unique style of shots

to the point that many baristas have tried to emulate the 

"Londinium shot" on other machines.

My moddified Gaggia Classic has a "Londinium Profile".

The Decent also has something similar.

So what is it?

It's a spring lever machine that uses pressurised pre-infusion at the beginning..

The technique it uses is something like a GS3 puck slam.

It really slams the puck with something like 25mls of water.

This very fast and early saturation of the puck compresses it much faster than is usual leading to a denser & thicker starting pour.

It's sometimes called a "water hammer".

The adapted "Londinium profile" for a standard lever machine involves

quickly hitting the puck with pressure (about 3-4 bar) and holding it there.

3 Bar appears to be the perfect pressure to balance capillary preinfusion with pressure preinfusion.

(3 Bar is also common in "Blooming profiles").

This gets the water through the puck evenly & quickly will minimal channeling.

The initial flow rate will be really low ... about 8ml/s (0.3 to 0.5g/s) range.

This will give you a beautiful thick top to your espresso.

After this, ramp up to 9 bar, then gradually drop back to zero

as the puck degrades.

Try to keep the flow rate constant during this second stage.

This second stage has much less body.

When you drink a shot like this it feels super creamy due to the thick top of the preinfusion.

In summary:

1. Pre-infuse:  8 ml/s, low pressure & hold at 3 bar.

                   (About 13 secs)

2. Post infusion: raise pressure and hold at 9 bar.

3. Final stage: decline to 3 bar.

You need to monitor the flow in these last stages.

Your aim is to keep the flow at about 2g/sec (2ml/sec).

This profile works really well on dark to medium roasts.

Usually, I aim for a 1:2 ratio

One important think to note is that although I use the measurement of pressure alot, what is also important is flow.

Pressure = flow x resistance

This type of shot is really tasty with milk based coffee like Latte