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I've recently bought my first espresso machine (a Rancilio Silvia). I'm now trying to dial it in, but don't know how to interpret the result:

My shot is not too fast (it does not splash out of the machine). It also takes about 5 seconds until coffee starts pouring out. However, the coffee does not flow as evenly as I was expecting. The first drops really shoot out of the machine and then turn into a quivering stream of coffee. In the end, the cup is not clean at the rim but rather a bit sprinkled with coffee drops.

Did I tamp too hard or why does this happen?

enter image description here

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    Welcome to Coffee SE! Nice question. It may be helpful to mention what kind of a machine you have.
    – Ivan Kapitonov
    Commented Aug 31, 2015 at 0:45
  • @IvanKapitonov Thanks, I've edited the question.
    – Niko
    Commented Aug 31, 2015 at 5:28
  • Can you post photos of the coffee puck? That can be very useful for diagnosing.
    – luser droog
    Commented Sep 1, 2015 at 3:52
  • Indeed - a picture of the spent puck still in the portafilter after your brew (e.g., this dialing-in article). See this Serious eats article on dialing-in -- specifically, start with determining the best coarseness of grind. Pre-infusion might account for the delay; portafilter bottom style might affect splatter... but let's start with the grind!
    – hoc_age
    Commented Sep 1, 2015 at 20:24
  • Great picture! I gave a preliminary answer below, but... what else have you tried? Have you varied (one parameter at a time!) your dose weight or grind coarseness? How does the shot taste?
    – hoc_age
    Commented Sep 2, 2015 at 16:32

2 Answers 2

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Looks like you've got too much ground coffee in the basket. What's the weight that you're using? It looks like the recommended dose for the stock basket is 14g, which is a bit lower than the "standard" of 19g or so.

You have an indentation (ring) around the outside of the grounds -- an indentation from the group/dispersion screen (in addition to the notorious protruding center screw on this model). If you're already tamping thoroughly, this could mean you've got too much coffee in there.

Here's a thread from Home-Barista on the Silvia around a similar topic. It discusses another way of diagnosing the dose -- inserting the PF with tamped grounds, then removing while still dry.

That article also talks about aiming for a dose+tamp to leave a bit of space between the tamped grounds and the screen: approximately the thickness of a 5-cent piece of space (1-2mm), which is a general recommendation (not just for this machine), though there is certainly disagreement on this. Another article from Serious Eats discusses this topic and notes that a "sludgy mess" can result, because the grounds will expand a bit when they absorb water. Your picture also looks a little "wet"; it could just be the picture, or perhaps a similar symptom.

Try a lower dose (14g) and do the dry-removal test, aiming for a bit of space between the top of the tamped grounds and the screen.

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  • I hope others have other ideas, too...
    – hoc_age
    Commented Sep 2, 2015 at 16:30
  • Thanks, I will try what you suggest. I was thinking that the indentation from the screw can probably not be avoided, and I just didn't notice the outer ring before. The puck is indeed a bit wet, but not super-soupy.
    – Niko
    Commented Sep 2, 2015 at 16:47
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    Turns out I was alreay putting in about 14g each time. But I noticed that the machine vibrates quite a bit (the cups start moving around).
    – Niko
    Commented Sep 4, 2015 at 17:30
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    Yes, the 'wetness' in the picture really shocked me. Does this machine not have a backflush valve?
    – luser droog
    Commented Sep 15, 2015 at 5:24
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    @luserdroog It does have one. Turned out the problem was the coffee and the grind, and also this overfilling to some degree - everything is fine now, thanks!
    – Niko
    Commented Oct 19, 2015 at 6:45
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Over fill grind basket loosely then skim off excess grind. Tamp grind to 30 PSI, fairly stout push, make sure grind around perimeter is pressed also. Give a finial press and twist. The size and consistency of grind is important too. My grind is almost the right size, but the first 2 seconds it is liquid-y but quickly transforms to a thick foamy look which is what you want. If it is liquid-y throughout the run the grind is too coarse. Note: I happened to have .001 thick brass shim and was able to place shims under my grinders stationary plate in order to finer grind.

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