I am using the Londonium L1 from 2013 and here is my question -
I did the following try -
I dose 18.5g on a 22g IMS basket. The coffee is a medium - dark Brasil cerado roast. I did pre - infusion of 20 seconds - yes really long PI and didn't had even one drop of coffee then i released the lever and had a 36g drink in 25 seconds. The espresso was quite nice and the Extraction was looking good however it seems strange that after 20 seconds of PI there was no drop of coffee.
Now if you will say that i should grind coarser i will have too fast Flow so...
Ziv Sadeh wrote: The espresso was quite nice and the Extraction was looking good
1) then there is no problem whatsoever ;-)
Ziv Sadeh wrote: however it seems strange that after 20 seconds of PI there was no drop of coffee.
Not at all strange. With the relatively low pre-infusion pressure, the wet and infused puck can more easily resist the boiler pressure and you also get a lower initial extraction pressure which, as you may notice, can yield delightfully subtle taste profiles.
The "wait for the first drop" rule is not always for the first generation Londinium, in my experience.
In my view it's best to use the first generation Londinium within the specsand as the specific tool it was designed for. Raising the boiler pressure a bit to, say, 1.35 bar is probably very possible but move it higher and the water flowing from it will get very hot, introducing more fuss than the advantage of a little more pressure is worth.
If you enjoy the current shots, enjoy these to the fullest as I did when I had the first gen version.
If you feel you want to move to the wider range of the L-R and vary the pre-inf pressure way up there, sell the machine and upgrade.
pre-infusion pressure greater than boiler pressure is really only useful for medium roasts and lighter
why? because the medium and lighter roasts are less soluble you need to use more coffee, hotter water, and push more water through the coffee
in addition the lighter roasts are drier because the roast has not been taken to the point where the moisture in the bean ruptures the cell structure of the bean to the extent that the oil in the bean can run out of the cell structure, so the light roasts need to be ground quite a bit finer than a traditional dark roast otherwise the water just shoots straight through the puck
traditional dark roasts are more soluble so all the parameters above move in the opposite direction
be aware that poor distribution is often compensated for by grinding finer than is optimum
unless you are a pretty hot shot barista it is critically important to use our distribution tool if you want to protect against poor distribution so be sure to use it thoroughly every time for consistent results
observe the sweating of the coffee on the face of the bottom of the basket during pre-infusion - you want the sweating to occur evenly over the entire surface of the basket ideally - if it is only sweating in some areas of the basket face it suggests the distribution could be improved
if the distribution is optimal you are likely to be able to grind fractionally coarser
the other thing i would try is to tamp lighter than what you currently are and keep the grind the same - this should allow pre-infusion to complete in a shorter time without changing the flow rate during extraction
i would be more than happy to sell you a machine, but my understanding is you like a fairly dark roast and a large shot volume
the elevated pre-infusion pressure will solve the issue you are trying to solve, but my concern is your darker roasts are going to taste a bit charred
for example, why not try a 17g dose in the 18g VST - i think this might take you in the right direction and the experiment will be a lot less expensive than buying a new machine
personally i would upgrade your grinder before your machine - i understand you have an E10/K10WBC and while it is a good grinder it isnt the ideal tool for a home environment - perhaps look at something like the Niche Zero if you like a darker roast as it has conical burrs and whilst it is new to market it looks like it will redefine the value equation for home grinders. the K10 has relatively high retention for home use which holds you back from accessing optimal tastes in your coffee
ps - i am no way connected with the Niche grinder project - i dont even know the name of the guy, far less traded emails or any other form of communication, i just think it looks like it is going to redefine that particular niche in the market at that price point.
You can do a lot with the original L1 machine if you pair it with a good grinder and dose it at Italian levels (7g singles, 14/15g doubles). In my case, using a Monolith Flat grinder and 1:2 to 1:2.5 brew ratios, I have no trouble pulling tasty shots from medium-light coffees, with extraction yield levels of ~22% and greater. (I run my boiler pressure at 1.2 bar throughout the year.)
RE the Niche - I bought one (although not yet a Londinium owner) and I am now sellling the wega grinder it replaced.
consistently good grind and now i almost never get any channelling on my rancilio silvia.