Never had a dry puck!

Beginner and pro baristas share tips and tricks for making espresso.
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#1: Post by LondonBunny »

Grinder: Niche Zero
Espresso Machine: La Marzocco Micra (brand new)
Beans: medium to dark roasts
14g basket

Failing Barista, wanting to be better :-(

New machine owner (coming from a Micra Casa Lever) trying to tame my brand new La Marzocco Linea Micra - whatever I seem to do, I always get a messy wet puck after brewing; in fact, I have never had a dry puck! More importantly, the end coffee has only occasionally been good, usually not great. Sometimes under-extracted sour and still wet.

I have tried:

- 14g, 15g, 16g in the 14g basket
- Grind fine enough for 20sec, 30 and 40 sec extractions
- Ratios 1:1.5, 1:2.0 and 1:2.5
- Pre-brew 0, 3+3 and 5+5
- Temp of 93 and 94°C.

And following best-practice puck prep - stirring to reduce any clumping, using a distributor, and then a tamper (no polish).

What might I be doing wrong? What am I missing? (before I put the Micra in the bin and go back to just my nice simple lever)

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#2: Post by Jeff »

Ignore water on the puck after the shot had been pulled. It is usually due to the geometry of the machine and how the exhaust valve works.

A puck screen, such as the 1.7 mm sandwiched screen ones can make things look better. It can also help keep your group screen cleaner, though does need to be cleaned itself. It will reduce the available dose in the basket slightly as well.

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#3: Post by cafeIKE »

Pucks are compost and as reliable an indicator as tea leaves.

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#4: Post by espressoren »

I can get a dry puck on the Micra if I stuff the portafilter to the max and grind a tad coarser, but that's not how I normally use it.

Even a puck with standing water on it after the shot will 1) - absorb most of the standing water on top of I count to five after pulling the portafilter, and 2) still pop out whole or nearly whole with a tap or two.

Since I generally only care about the post shot puck in terms of the cleanup, the moist puck doesn't really bother me. I certainly wouldn't toss out a machine that makes great espresso for an aesthetic reason like dry puck. Focus on improving the results, the post shot puck is a distraction unless you're checking it for channeling or something.

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#5: Post by Jake_G »

Also, be careful about the recommendation to use a puck screen.

I am all for using one, but the screw can damage the screen if you don't first verify that you have enough room for it. I recommend the "Nickel Test" as a sure-fire way to ensure the puck screen will fit before you risk it.
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#6: Post by erik82 »

What beans are you using? Darker roasts tend to have a greater chance of wet pucks then lighter roasts. Also did you test if there's enough headspace as putting 16gr in a 14gr basket is asking for problems. This can also lead to a muddy puck. But in the end the muddy puck will tell you absolutely nothing about the shot as others have already written.

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#7: Post by baldheadracing »

LondonBunny wrote:What might I be doing wrong? What am I missing? (before I put the Micra in the bin and go back to just my nice simple lever)
FYI, in general, a pump machine's puck will not be as dry as a puck from a lever machine.

In almost all spring lever machines, including the MCaL, a column of air is pushed downwards through the puck at the end of the shot by the spring - so the remaining water is pushed out with gravity combined with the spring's remaining force. (In a direct lever, you somewhat control the size of that column of air; gravity remains the same.)

In a pump machine with a three-way valve, air is pulled up through the puck at the end of the shot - so against the force of gravity. Thus, the action of the three-way has to be stronger than a lever machine's spring. However, it does take a combination of coffee, dose, grind, basket, headspace, and dispersion block/screw to pull enough air through the puck to suck most of the remaining water past the dispersion block/screw. The location of the three-way valve also makes a difference. If the combination of all of those isn't just right, then you are usually left with some water at the top of the puck. If the combination isn't really right at all - typical of some single baskets - you are also left with a mess in the basket.

As I am used to dry pucks from lever machines and don't want to fiddle about, what I have done with the Micra is use a 0.2mm thick puck screen (ETA: 14g/15g in the stock LM 17g basket). After removing the portafilter I can use the puck screen to squeeze out water from the puck to give a dry-enough puck for easy removal.
-"Good quality brings happiness as you use it" - Nobuho Miya, Kamasada

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#8: Post by Espressmyself »

Have you tried a larger 18g-20g basket with an 18g dose in it? Also, are other LM Micra owners having similar issues?

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#9: Post by LondonBunny (original poster) replying to Espressmyself »

Yes, I have a VST 22g basket and that also is wet.

I am not going to stress about it (following advice here), but it does feel odd - I am not sure if other owners see the same.

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#10: Post by NelisB »

With my lever machines I got dry pucks. With the Micra they are not as dry. With some coffees they will come out in one piece, others fall apart. I don't care, the extractions taste so much better.