Filter paper: HIFLUX and SOLO SPIN
What I notice when I change the paper
I am a brewer. Everything in this article comes from brewing at competitions, at home and in our cafés, and from the research I read to understand what I taste. The cup always has the final word.
These are my observations from years behind the brew bar. Take them, test them, and keep what makes your cups better.
What drew me to HIFLUX in SOLO is the mouthfeel. SOLO already gives me a round, full cup. HIFLUX adds a soft coating on my tongue, and with some coffees the aroma stays with me longer after the sip.
Brewing with this paper every day taught me to pay attention to something I overlooked for years. How the paper sits in the brewer. I keep the Wave shape for some brews, fit it closer to the wall for others, or lift it gently onto the rim. That small detail is what this article is about.
The filter material never changes. Only the physical setup does.
What I feel in the cup
Some of my favourite brews have a slightly oily texture. I love the way they coat my mouth, especially when the flavours stay clear.
That coating made me curious about coffee oils. Lipids influence how aroma compounds are held and released, and how a liquid feels in the mouth. It is not as simple as more oil, more aroma. Different aroma compounds behave differently, and mouthfeel comes from more than oils alone.
So I trust the feeling. The coating, the roundness, the aroma that lingers after the sip. Those are the qualities I compare papers by.
Soft paper needs a little support
Wet HIFLUX feels soft and flexible, almost like a kitchen towel, yet it holds together nicely in my hands.
The material is lyocell made from wood pulp, with continuous fibres arranged in a three dimensional structure. Strength and stiffness are different things. The paper resists tearing, but it does not hold a rigid shape on its own. Under the weight of coffee and water it settles closer to the bottom of the brewer, which changes its contact with the base and the space left for drainage.
Before I add coffee, I check where the paper sits. Supporting it is part of preparing the brew. Here are the four ways I do it.
Four ways to place HIFLUX in SOLO SPIN
Fit the Wave against the wall
I prepare this one dry. I open the folds of the Wave paper and press them against the inside wall of SOLO, then rinse. The wall supports more of the sheet, and the closer fit narrows the open spaces around the sides where water could slip around the coffee bed instead of through it.
There are two ways to shape it. By hand with a spoon or your finger, or with the Pressor tool. I cover both in Fold your filter for a low bypass brew and How to flatten wave filter paper with the Pressor. The result is low bypass rather than zero, because the real path of the water still depends on the fit, the coffee bed and the pouring.
Fold a flat HIFLUX sheet
Same idea, different starting point. I take a flat HIFLUX sheet and fold it into a shape with a flat bottom that follows the inside of SOLO, forming the folds myself instead of opening Wave pleats. We made a folding video and a 3D printable tool for anyone who wants help with the shape. After fitting and wetting, I check that the bottom is level, the sides are supported and the upper edge is high enough to hold the brew.
Rest a size 185 paper on the rim
This is the setup I use most often. I lift the paper slightly so its upper edge rests on the rim of the dripper. The bottom forms a shallow cup with a little space underneath, and the rim carries the paper instead of letting it all settle towards the base. It needs only a small lift. I just check that it sits evenly before adding coffee.
Here I am not trying to fit the sheet against the wall at all. My attention is on where the bottom sits and the space beneath it. It is a gentle adjustment that keeps one paper, one layer, and the folds as they are.
Two layers
The fourth way uses two sheets, and I brew it in two combinations.
HIFLUX double layer. Two sheets of the same lyocell paper, one inside the other. I tested this with HIFLUX FAST and the flow rate is about 19.5% faster than a single sheet.
PURITY outside, HIFLUX FAST inside. PURITY goes into the brewer first, with HIFLUX inside it, touching the coffee. The outer filter supports the softer inner sheet, and it also filters. The liquid passes through both layers, PURITY catches material that passes through HIFLUX, and the extra layer changes the resistance to flow.
Either way, this is a combination of two filters, and I adjust the recipe for it. When I want to know HIFLUX on its own, I start with one of the single paper setups.
Why I connect paper shape with the roast
Roasting changes both the chemistry and the inner structure of coffee. Even beans roasted to a similar colour can have different pore structures, depending on how they were roasted. This matters at the brew bar. The same recipe simply does not extract every coffee the same way.
When some parts of the bed give up their soluble material more easily than others, sending more water through the bed lets those differences show. Grind distribution, pouring and uneven flow shape the cup as well. What I rely on is how the coffee answers my adjustments.
With Wave, the folds leave routes for water to travel around part of the bed. More bypass can soften the strength of the cup, and the whole expression can feel gentler and more open. When that is what I am looking for, I begin there.
When a coffee stays balanced as I take more from it, I try a closer fit, with more water through the grounds, searching for more sweetness and detail.
The same recipe simply does not extract every coffee the same way.
I do not use roast colour as a shortcut. A light roast can be beautifully developed and welcome more extraction, and a stronger cup is not automatically a more balanced one. The question I return to is always the same. Does this change make the coffee sweeter and more complete, or does it make the balance less comfortable?
The roast helps me understand why coffees respond so differently. Tasting tells me which way to go.
Try it yourself
Start with a coffee you know well. Compare your usual Wave setup with one of the single paper alternatives, keeping the dose, water, grind and pouring the same. That first comparison shows you what the placement itself does. From there, adjust each setup separately until you find the cup you prefer.
Brew time is useful information, but let the taste decide. Try both cups as they cool, and notice the sweetness, the aroma, and how the coffee feels during and after the sip.
Notice what changes, wonder about the reason, and check it against the cup.
That is my whole approach. And if you taste something different from what I describe, that is the interesting part. Your cup has something to teach me too.