# coffee "flow rate" question



## bjj22 (Mar 9, 2013)

Hello. This is my first post. I have a question about our Silvia which has been troubling me for a while. Essentially, when we make 2 espressos in quick succession, the second espresso consistently seems to take longer to make. Eg with the basket filled to the same height (post-tamping), if the first shot took 20s to produce, the second could easily take 30s+. Alternatively, we need to put fewer grounds in the basket in order to make the same amount of espresso in the same time. Does anyone know if a) this is normal, and b) what is the explanation?

We use a variety of different beans, often from square mile, usually fairly sweet.

Rancilio rocky grinder, ground quite fine

Double basket, filled by eye (not by weight)

Basket cleaned either with water or with brush between shots - doesn't seem to make any difference.

I occasionally wonder if there are somehow more grounds in the 2nd espresso even though it looks the same. I could easily be imagining it but when engaging the basket to the espresso machine, the second one sometimes seems to require more force. I suppose weighing the grounds might answer this question.

Would be good to get other opinions on this.

Many thanks.


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## Glenn (Jun 14, 2008)

Its entirely possible that there are more grounds in the second dose if you had cleaned out your grinder previously.

If your grinder retains grinds then this will be the issue, as these will be ejected when you next dose


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## bjj22 (Mar 9, 2013)

Hi Glenn, thanks for your reply. Not sure I totally understand though. The grinder dispenses the grinds directly into the basket whilst pressing the button, and release the button it stops, ie it doesn't dispense a pre programmed amount. We don't clean the grinder out regularly, should we be?



Glenn said:


> Its entirely possible that there are more grounds in the second dose if you had cleaned out your grinder previously.
> 
> If your grinder retains grinds then this will be the issue, as these will be ejected when you next dose


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## bjj22 (Mar 9, 2013)

PS I realise I should've pointed out our grinder doesn't have a "doser" ie it is this one http://www.amazon.com/Rancilio-Rocky-Doserless-Coffee-Grinder/dp/B000AYWU9K/ref=sr_1_1?s=home-garden&ie=UTF8&qid=1362845057&sr=1-1&keywords=rancilio+rocky not this one http://www.amazon.com/Rancilio-ROCKY-Burr-Grinder-Doser/dp/B0007XY7MM/ref=sr_1_2?s=home-garden&ie=UTF8&qid=1362845057&sr=1-2&keywords=rancilio+rocky


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## Glenn (Jun 14, 2008)

Yes, you should clean your grinder out regularly as even with a doserless, grinders retain a gram or 2 of coffee after each dose.

Try giving it a clean then weighing beans in, and coffee out. The difference in weight will be the grind retention


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## bjj22 (Mar 9, 2013)

Thanks glenn. I'll give it a try. It feels to me like it shouldn't be the grinder though as I fill the basket by eye - for example up to the line (post-tamping). Whilst there may well be grounds retained in the grinder, surely I will be compensating by visually adjusting the amount of grounds I dispense? Obviously I won't be spot on each time, but this should be a random error - whereas in this case, the second shot consistently takes longer for the same amount of coffee to be produced, implying a systematic error..

To me this suggests either somehow the second basket looks less full than it is (not sure how that could happen) so I add too many grounds to make it look right, or for some reason the machine dispenses the hot water slower the second time. Maybe something is retained on the espresso head after the first cup?

I'm totally over-thinking this but would be nice to know!


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## Steve_S_T (Dec 7, 2012)

Whilst I've never used a Silvia is it possible that the boiler pressure has dropped whilst dispensing the first shot and doesn't have time to fully build back up before you pull the second so lower pressure = slower pour? I suppose if you wait an extra minute or two between shots you could rule this out (or in).

Steve.


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## bjj22 (Mar 9, 2013)

Will try this too - thanks Steve!


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## mike 100 (Jul 15, 2010)

May be worth temperature surfing to ensure the boiler is up to the correct temp, have a look at http://www.seattlecoffeegear.com video's by Gail & Kat to explain properly, but it invloves running off water from the boiler (hot water tap) until the boiler light comes on,when the light goes out wait 30 seconds then pull your shot, the Silvia should be at the correct temp for coffee.And as Glenn says weigh your doses to eliminate error


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