You have a DeLonghi Dedica, a KitchenAid Artisan, or another compact entry-level machine. The espresso looks like it came from a café: thick crema, nice colour. But it doesn't taste right. Or you bought a decent espresso machine, the coffee suddenly runs through watery, and the crema is gone. What happened?
The culprit sits in the portafilter. More precisely: in the basket itself.
What a basket is actually supposed to do
When brewing espresso, pressure builds up because water is forced against the resistance of the coffee puck. The puck has to be able to create that resistance. Three things are needed for that: fresh coffee, the right grind size, and a basket that doesn't distort the process.
A standard, single-wall basket works transparently: it filters the espresso but doesn't artificially restrict the flow. What goes in comes out. The extraction happens in the puck.
Double-wall – what that means
A double-wall basket has a second layer built in. From above it looks like any other basket. From below there's only one tiny hole – that's the second wall. The espresso runs through the coffee puck, passes through the first filter surface, and then has to push through this restriction.
That's exactly where the key thing happens: pressure builds up before the restriction. Behind it, pressure drops instantly to atmospheric – and at that moment, dissolved CO₂ comes out of solution. Foam forms.
But this isn't typical espresso crema, and the difference is mechanical: real crema forms because CO₂ under ~9 bar of pressure bonds with coffee oils and fine coffee particles during extraction to create a stable emulsion. In a pressurised basket, that doesn't happen. The foam forms only after the restriction, through the pressure drop – not through the extraction process itself. The result is a bubbly crema: airier, less viscous, different in texture.
This isn't a flaw – it's intentional. The basket simulates the pressure the coffee puck can't generate on its own.
The photo shows it clearly: in the sawn cross-section you can see the two layers of metal with the gap between them. All of the espresso has to pass through that one small hole at the bottom.
Why machines come with these baskets
Entry-level machines include double-wall baskets as standard. The reason is straightforward: most buyers don't grind their own coffee. They buy pre-ground coffee from the supermarket. That coffee is almost always ground too coarse for espresso – and often already weeks or months old.
Old coffee loses CO₂. CO₂ fills the spaces between coffee particles in the puck and builds up resistance. Without enough CO₂, without the right grind size: the espresso runs straight through, no pressure, no crema.
The double-wall basket fixes this problem. It's a workaround – but a useful one, as long as the right conditions aren't in place.
Here you can see the bottomless portafilter we developed specifically for the Dedica. Bottomless portafilters are more advanced territory though. Start with the 2-spout portafilter we also offer.
The problem when switching to single-wall
This is exactly where the most common confusion comes from: someone buys a better portafilter or a different basket, switches to single-wall – and suddenly the crema is gone. The coffee runs through thin.
The basket is now working correctly. And that's precisely what exposes the real problem: the coffee is too old, ground too coarse, or both. A single-wall basket can no longer hide that.
For the DeLonghi Dedica, we developed our own 2-spout portafilter and sell it ourselves. We also offer precision baskets in 51 mm – designed for use with fresh, properly ground coffee. Switching to single-wall gives you a setup that matches the ambition.
From above, both basket types look identical. The difference shows up in cross-section and in what ends up in the cup.
What now? The next logical step
A single-wall basket only works when the other factors are right:
Fresh coffee. Two to three weeks after roasting is ideal. Three to four months maximum, depending on the packaging. After that, the CO₂ needed for a clean extraction is gone.
The right grind size. Pre-ground coffee usually lacks both: fineness and freshness. Budget grinders often lack the fineness too. Anyone serious about making espresso needs a grinder that can go fine enough – and one that lets you dial it in for espresso.
A good hand grinder costs less than a DeLonghi Dedica. Entry-level single-dose grinders cost roughly twice as much. That's the biggest quality jump in espresso – and it happens at the grinder, not the machine.
Anyone who makes that step will notice: the crema that forms now is denser, creamier, different. Not the bubbly version from the pressurised basket.
Crema = quality?
Short answer: no.
Crema shows that the coffee is fresh and the grind size is correct. It's an indicator for those two factors. A coffee can have a lot of crema and still taste bad – simply because the bean doesn't deliver or the extraction is off.
When no crema forms at all, that signals the coffee is past its peak or the puck isn't building enough resistance. It's a warning sign, not a quality marker in itself.
When the double-wall basket makes sense – and when it doesn't
The pressurised basket makes sense as long as the basic conditions for single-wall brewing are missing: no grinder, no fresh coffee, no way to adjust the grind. That's the scenario it was designed for, and it does its job.
But once you start genuinely understanding espresso – grinding fresh, dialling in the grind, working with a scale – the double-wall basket gives you nothing. The opposite, in fact: it hides the feedback you need most.
Switching to single-wall isn't an upgrade that automatically tastes better. It's the step where the dialling-in begins.
Want to get the most out of your Dedica?
In our online course, Felix (German Barista Champion 2024) and Andrea show you step by step how to pull consistently good espresso. 6 modules, 20+ lessons, lifetime access.
