Many roasters give preparation recommendations for their coffees. Here is a typical one (for Verve's Streetlevel):

IN: 19.7g // OUT: 29-30.5g // @23-24s

When I try to makes sense of the timing for my L1, I don't know whether to include some pre-infusion in the total. More generally, I wonder if the declining pressure and temperature profiles of lever machines mean that the total time should, in any event, be longer as (presumably) the extraction levels are declining throughout the shot.

Matt

Matt:

I think you're right. I don't know if there is a single conversion because of differences in lever machines. However if you compare my review to others of the first in the Favorite Espressos 2016 series, you'll see how I dialed in compared to those using pump machines. To answer your question more directly for my Conti Prestina, here's what I wrote.

The roaster's recipe was "18 gm dose, yielding 50 - 60 ml in a 25 second extraction with water hitting the coffee between 201 and 204°F." 50 ml of the coffee weighed 36 gm. I dialed in at "18 gm in, 35 gm out, using a 30 sec preinfusion, followed by a shot after releasing the lever of 33 - 35 seconds."

Added: Noting replies that have followed, like them, I'm dialing in by taste. However I think you can get a good sense of a starting shot from a recipe by allowing time for preinfusion and letting the shot run a bit longer to take advantage of the declining spring pressure.

mathof wrote:Many roasters give preparation recommendations for their coffees. Here is a typical one (for Verve's Streetlevel):

IN: 19.7g // OUT: 29-30.5g // @23-24s

When I try to makes sense of the timing for my L1, I don't know whether to include some pre-infusion in the total. More generally, I wonder if the declining pressure and temperature profiles of lever machines mean that the total time should, in any event, be longer as (presumably) the extraction levels are declining throughout the shot.

Matt

Recipes are general guides - and people can get stuck on them , especially roasters recipe ( again the below is not directed at the OP per se but more general ramblings ) .
"I followed the recipe , it doesn't taste good ".
Too many variables to undefined , the biggest one being your personal preference , so kill the shot by weight not time ... Adjust by taste , learn how to adjust based on the balance or lack of you find in the cup .
In the example above you presume they are pulling at 9 bar , but are they , what temp are they pulling at ? Too many things to try and copy , too many things you haven't been told .

Excellent! Can't agree more.

Séb wrote:Excellent! Can't agree more.

+1.

For me it depends on the beans, the roast and what type of drink I am making. I might use a single basket, a traditional double or a triple and anything in between using VST baskets and the "formula" is always changing.

Yep, ignore the recipes. Learn to dial a bean in properly on your equipment, to suit the flavour profile you prefer.

I use the recipes to get a gist of what brew ratio they intend you to taste it at and use it as a starting point, ignoring everything else. Based on the roast and origin I have a good idea on my gear what starting dose, temp, flow rate I'm looking for and then go from there.

Thanks to everyone for answering my original question. I think you all agreed that it's better to dial-in the coffee for your machine than to worry overly about matching the roaster's formula (although it may give an indication of the general intentions of the roaster). Gary's link to the reviews of Caffè Lusso's Gran Miscela Carmo was very instructive and interesting. I wish Caffè Lusso exported their coffees, as I'd like to try this one for myself in London.

Matt