Strange changes in extraction timing

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#1: Post by roccster »

Yesterday morning i did my "regular" latte. The extraction was really good, approx. 20-25 sec. When I got home later that afternoon I turned the machine on (Fiorenzato Bricoletta E61), waited for 30-40 minutes and prepared for extracting my afternoon espresso. The coffee in the grinder was the same bean as I ground in the morning. I ground the same amount as I always do, tamped it, flushed the Bric. and started the extraction. Pretty much nothing happened. After maybe 20 sec. a few drops started to emerge, and after another 20 sec a very slow extraction. I didn't wait for it to finish. I did another try and that was probably worse then the one before. A bit worried that the machine had broke down on me again I now changed the coarseness on the grinder (4 steps), and now the extraction went fine. The espresso looked, and tasted as it should.

So here is where I start to wonder. Can the roast of the coffee be so different so that all of sudden you need to change the grinder coarseness? Or is it perhaps something wrong with the pressure?

I made my latte this morning, and I had to go down a step on the grinder, still I am a bit worried though.

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#2: Post by Carneiro »

I've never experienced something like that, but a lot of home and professional baristas have problems with climate changes during the day, mainly humidity.


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#3: Post by HB »

Are you weighing the coffee dose? Because a variation of a couple extra grams of coffee could cause unexplained changes in extraction timing. This is especially problematic for grinders that compress the grounds as they exit the chute (e.g., Rancilio Rocky). Digital espresso or a way to consistency elaborates on this point.
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#4: Post by JonF »

I can have the same type of changes in grind. As mentioned above, I also blame it on changes in humidity.

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#5: Post by cannonfodder »

Environmental changes will have some effect but I have never had that extreme of a shift. It sounds like you simply had a higher dose.
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#6: Post by cafeIKE »

A drop in humidity, coupled with stales from the morning grind, could cause the change.

When the humidity drops, beans fracture more readily and create more fines, slowing the flow. A 10% humidity change is about 1 tooth on the grinder or about 0.5s on the timer or about ¾g in a single

roccster (original poster)
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#7: Post by roccster (original poster) »

No I am not weighing the dose, so that sure can vary up and down a bit.

The change of humidity, and the explanation on the grinder (I have a Rocky), sounds logical. Spring here in Sweden sure has raised the humidity inside the house, compared to just a week ago.

Thanks for your input!

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#8: Post by another_jim »

Did you grind with a nearly empty hopper in the morning and refill it in the afternoon? This is one of the major and least known causes of dramatically changed grind settings.
Jim Schulman

roccster (original poster)
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#9: Post by roccster (original poster) »

I usually tap the grinder properly when finishing the grinding, but since this was done in the morning my mind might have been in some other place.

Just finished a double and it seems to work as usual. Very strange behavior but atm my money is in the humidity.

Thanx again!

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#10: Post by Javacat »

This is a common phenomenon due to a change in humidity. I see it all the time. My shots vary from 30 seconds in the morning to 45 seconds in the early afternoon, or sometimes just a drip as you mentioned. If you want to test this yourself go to any Wal-mart or Target and get an inexpensive hygrometer and monitor the humidity yourself. Fresh coffee is very hygroscopic meaning that is absorbs or repels moisture very easily like a sponge. If you are in a room with lots of windows then just the opposite may occur if it happens to be sunny out where the shots that had been dialed in the morning could flow way too fast later in the day. It is also true that a shot will appear to have a much slower flow rate if the grounds are not fresh, i.e., if they were left in the grinder from earlier. This is due to less crema in the shot. If you want to test this then about the only way is to weigh your shots and compare them. Then if there isn't much of a difference then you'll know that you are probably getting stale ground in your shot and should probably do a more thorough cleaning with a brush and shop-vac and purging prior to pulling your shots in the afternoon.