takeshi Senior Member Joined: 12 Oct 2002 Posts: 989 Location: Houston Expertise: I live coffee
Espresso: Alex Duetto 3.0 Grinder: Super Jolly Roaster: Amaya Roasting
Posted Tue Mar 1, 2011, 2:09pm Subject: Re: Stumped with my Rancilio Silvia
So as i understand it, if I increase the coffee i should see a slower flow rate? I've also heard that it should be easier to get the desired results from the double basket so I have been experimenting mostly with that. Is this correct?
The problem in your specific case is that Silvia prefers to be underdosed so you're really limited in how much you can updose. Increasing tamping pressure can also help but not by the margin that you need.
As others have said, you really need a good grinder. It doesn't matter how good Intelligentsia's grinder is. The grind needs to be tuned specifically for your machine, your beans, etc. They can get the grind to roughly where you need it but you can obviously see what "roughly" means in this particular case (8-10 seconds pull versus 30).
You also need a good grinder because your grounds are probably stale by the time they make it into your home. Stale grounds make it extremely difficult to get a good shot. Fast pulls are a common symptom of stale grounds. Your beans should be ground and used immediately.
Glad to hear it! Not to pile on, but I would be really surprised to hear anything was wrong with your Silvia. It's not that your grind was BAD, per se, just that it wasn't right for your machine. You have to dial in your grind and a generic grind, even with the best commercial grinder, is unlikely to be just right. Very small adjustments with my grinder have produced dramatically different results in my Silvia. From not pouring at all, to pouring quick and watery, with just a few clicks.
Posted Tue Mar 1, 2011, 3:57pm Subject: Re: Stumped with my Rancilio Silvia
The whole thing is simple physics really. The water flows from your machine at a certain rate depending on the pressure. The flow rate you are currently experiencing through the bed of coffee is giving you 2-2.5 oz in the cup 8-10 sec. Therefore, in order to slow the rate at which the water is flowing through the bed of coffee...you need create more resistance. There are three ways to do this...
Grind finer (absolutely cannot do espresso without one of these by the way)
Increase the dose (i.e. more coffee in the basket)
Tamp with greater pressure
You said that you are already filling the basket to the top before you level and tamp; as a result, you really can't (shouldn't) increase your dose. Chances are, the bed of coffee is probably already hitting the shower screen. You can check this however...fill your basket like usual, level, tamp and then lock the pf into the group head...then remove...if you can see an indentation of the shower screen (the screen, not the screw) on the bed of coffee, the basket is over dosed...i.e. already has too much coffee in it.
Regarding the tamp...you could probably run over the bed of coffee with your car...but I still don't think that would give you enough resistance for a flow of 2-2.5 oz in 25-30 sec. That's simply too much ground to make up with the tamp alone. Even if you could, you still wouldn't have a good coffee extraction.
This, my friend, is why you need a grinder. Very simply put, the grinder is the tool which allows you to have control over the extraction rate of the coffee. Without that tool...there really isn't much you can do. To really get this correct without a grinder, you would have to take your machine to Intelligentsia so they could dial in the correct grind for your machine, using your coffee, and your tamp. Sorry.
Now, before anyone chimes in regarding my gross oversimplification of the extraction process...I will say that you should also check out the site below for a much more detailed explanation of the extraction process and how the grind affects that process.
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