Dry vs. wet portafilter

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#1: Post by LittleCoffee »

I'm having trouble getting consistent shot timings. I'm wondering if the issue is that a dry portafilter behaves differently to a wet portafilter and therefore grind setting and tamp need to be calibrated differently?

My set-up
Alex Duetto IV
Baratza Sette 270WI
A double sided tamp/distributor thing which tamps to a fixed volume

Here's what's happening. Most days I only make one shot. I don't bother flushing water through the portafilter before I pull (I probably should, but I don't), so it's dry. I'm grinding 18g through my calibrated Sette and distributing/tamping with my calibrated tamper thing. The coffee starts coming out 4-5s after pump start and I get 36g of great espresso out in 25-28s and I feel good about life.

Some days though I decide, man that shot was good. How about another one? And then the portafilter is wet. I repeat the process exactly. This time, without fail, I get 36g in 15-20s. Coffee still starts 4-5s after pump start.

The only difference between these two is whether the portafilter is dry or wet - unless there's some other variable I'm missing?

I don't have an open portafilter and I am just too beginner to be able to tell whether the puck has channelled or not - there's nothing obvious to me.

So I guess my questions are:
1. Is it possible that a wet portafilter just needs finer grind and more tamping than a dry one?
2. If not, does that mean channeling is the likely culprit in the wet portafilter case? in which case should I be grinding finer/tamping more or the opposite?

Many thanks in advance for any help!

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#2: Post by henri »

A wet basket may cause the puck not to adhere properly to the basket walls, or so I've read - in this case, some of the water is just going to bypass the coffee, which would explain the quicker shot time. You should always wipe the basket dry with a towel before preparing the puck. But maybe you are already doing this? (If so, then I am at a loss to explain what's going on, especially if the effect is systematic.)

I put off buying a naked portafilter for a long time as I didn't see the point. But ever since I got one, my extractions have improved considerably. It really is a valuable diagnostic tool, and also has the added benefit of heating up quicker than a conventional portafilter with all that extra mass.
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#3: Post by Nunas »

There is another variable, the grinder. While the Sette is low retention, it's not no retention, especially on darker roasts. On my Sette, I have one of the buttons programmed for a 5-gram shot, which I use to purge if the grinder has been sitting for a while. Try that and let us know if this makes a difference. It certainly does here, although the results are usually the reverse of what you're experiencing. That is, the second shot is usually slower, not faster.

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#4: Post by BaristaBoy E61 »

Based on my experience, I would advise always drying a wet/damp portafilter basket, using a naked portafilter to monitor shot development and to use a shot mirror to easily view the bottom of the naked portafilter.

Other than also having direct plumbing and draining, the above mentioned procedures will deliver consistently better shots. Continue using your distribution/levelling tool well.

"You didn't buy an Espresso Machine - You bought a Chemistry Set!"

LittleCoffee (original poster)
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#5: Post by LittleCoffee (original poster) »

Really helpful tips - thanks everyone.

The drying with a towel goes exactly the opposite to what I would have tried as I've never seen that done anywhere - I would have tended to wet the portafilter first time round and try to calibrate for that rather than dry the portafilter for the second shot and keep everything as is. Well for sure using a towel will mean less calibration! And now that I think about it, the Duetto did come with a strange black towel I never figured out what it's for - could it be that that is its function?

Also good shout on Sette retention potentially contributing. Will play around.

As for the open portafilter - waiting for the bank balance to rebuild after the initial purchase :-)

Thanks again everyone.

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#6: Post by Davi-L »

An elegant solution might be to buy a 2nd basket for your portafilter. Then it's clean, dry and ready to go. I have a dozen that I cycle through the dishwasher every few days.

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#7: Post by thesharpener »

I use a microfiber barista towel to wipe the basket dry before dosing.

When you distribute grounds, are you stirring with a WDT tool, or is it a chisel-type leveling tool?
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#8: Post by LittleCoffee (original poster) »

I can confirm that it was indeed the wet portafilter causing this issue - drying it for the second shot makes this issue go away 100% of the time so far. Thanks for all your helpful suggestions.
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#9: Post by Mat-O-Matic »

Yes, always wipe dry and clean with microfiber before grinding coffee into the basket. Perhaps what you've seen is an older practice of rinsing old grounds off a used portafilter while flushing the group. That was a bar method of keeping basket and group clean-ish during volume, though it still should be dried before dosing.
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#10: Post by Flannelsec »

I can never seem to get the portafilter dried well enough to keep the shots consistent on the second shots so I ended up buying a second basket and portafilter to keep my shots consistent.