I'm new to making espressos. But one thing I struggle a lot with is channeling. Or at least perceived channeling. I don't know if the bitterness is from channeling or just over extraction or just how the bean is supposed to taste. I also don't have a bottomless. But the puck I get afterwards is full of holes and not consistent.

That's where I came across an item called puck screen, explained here according to him the puck is much more consistent and dry, and less channeling.

Is this true? If so, which brand/product is best for this?

TL;DR

In my opinion, most problems with channeling are due to puck prep, assuming an adequate grinder and fresh coffee.

Entry-level machines and at least one high-end machine can put greater demands on puck prep.

Unless your prep is already "on", a puck screen isn't going to magically resolve issues.

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I find the BPlus screen definitely makes my cleaning easier.

Some, with high-end gear and skills, report subtle improvements in EY. These are people who already have resolved their basic prep issues.

Some, who pull "turbo" (coarse-grind, high-flow) shots with modern flats, believe that it helps a bit with puck integrity under those extreme conditions.

I use a BPlus for the first reason, and haven't confirmed the second.

The Flair 58 screen is supposedly the same OEM as the BPlus. I haven't tried any of the newcomers.

Can you elaborate on the entry machines being more demanding on the puck prep? Is it putting out too much pressure?

Some entry-level machines do a very poor job of spreading the water over the dry puck. Some are to the point of having a jet of water that effectively drills a hole in the puck. Others just aren't very even. A hypothesis is that if the puck is not evenly wetted before ramping up pressure that the wetter areas will tend to have greater flow than the drier areas. In the worst cases, this would lead to visible channeling. In lesser cases it suggests that the drier areas are not as well extracted as the wetter areas, impacting the flavors in the cup.

My experience is that lower pressures (6-8 bar, in the basket) can improve the flavor in the cup for some coffees and machines. There are some funky things that happen with a coffee puck above somewhere around 9 bar, where increasing the pressure doesn't increase the flow the way you'd expect. It is as if the puck gets "over-compressed" at those higher pressures. I have no idea if this makes a puck sturdier or more prone to channeling. I adjust my pressure for taste.

Jeff wrote: The Flair 58 screen is supposedly the same OEM as the BPlus. I haven't tried any of the newcomers.

I have confirmed by testing both screens side by side (Flair 58 and B-Plus), using three different coffees that they function exactly the same with respect to extracted amount in the cup and time to extract.

Thanks which is more affordable do you know?

Flair 58, the B-plus screen has to deal with a massive shipping charge, even on Amazon.

yalag wrote:Thanks which is more affordable do you know?

The Flair 58 screen will save you about $20.00 after shipping, last time I looked.

There are other brands available for much less. I've no idea how good they are. I expect that any screen of the same mesh size would work the same. The mesh sizes I've seen are 50, 100 and 150 um. From photos, it would appear that all of them have multiple layers and are around 1 to 2 mm thick. One exception would be the one from Coffee Sensor, which is single layer, like the ones sold for Aeropress.