SOLO Coffee Dripper Review: Zero-Bypass Brewing, Design, and Real-World Performance

 Lately, I’ve been brewing my daily coffee with the Lyocell wave filters I picked up not long ago, and honestly—I’ve gotten a bit tired of my copper Kalita-style three-hole dripper. So naturally, I started looking for some new “toys” to make better use of these filters. Haha.

If we’re talking about the most popular drippers over the past year, the SOLO dripper—used by the 2025 World Brewers Cup champion, Captain George—definitely deserves a spot on that list. So I got one myself, and I figured I’d share both my hands-on experience and some thoughts on its functional design.

Interestingly, if you search for “SOLO dripper,” you’ll find quite a few 3D-printed versions online. Personally, I think it’s worth supporting the original Czech design. Yes, the price difference is significant, but I’m willing to pay for good design.

Speaking of flat-bottom drippers in general, their biggest defining trait is consistency. They tend to produce a cup that’s full-bodied, round, and well-balanced in flavor. They’re forgiving, stable, and honestly just “reliable workhorses.” If you’re looking for consistency, a richer mouthfeel, or simply a beginner-friendly dripper that’s hard to mess up, a flat-bottom design is an excellent choice. So from a design perspective, using this shape as a foundation for accessibility and versatility is definitely a smart move.

Like many modern drippers, the SOLO comes in a wide range of colors to appeal to today’s demand for personalization—cream white, sakura pink, crystal blue, egg yolk yellow, coffee brown, graphite black, blueberry purple, and more. When I saw all these options, I kept thinking: with so many colors available, why does this “coffee grounds version” stand out to me the most? Brewing coffee with a dripper made from recycled coffee grounds just feels like a kind of poetic “return to origin” (okay, what am I even saying? Haha).

There’s actually a small story behind this version. The SOLO dripper was designed by Czech coffee enthusiast JACKIE TRAN. I checked out his Instagram, where he shared the inspiration behind developing the coffee grounds version. He wanted to create something natural, beautiful, original, and durable. At first, he struggled to find the right material. Then he realized that coffee grounds themselves have a meaningful connection to the brewing process.

From there, he began experimenting—but it turned out to be far more complex than expected. Coffee particles behaved unpredictably, forming repeating patterns: sometimes squares, sometimes double-Y shapes, depending on pouring techniques and curing times. He aimed to achieve a controlled layered appearance with depth and clarity, which took several more months of testing. The final production version we see today has a much more even distribution of coffee grounds, with a visually pleasing result.

As for materials, the core of this dripper is polypropylene (PP), a very common food-grade plastic. Its biggest advantages are that it’s lightweight, durable, and safe. PP is a high-performance thermoplastic widely recognized as safe for food contact. It’s odorless, tasteless, non-toxic, and produced without BPA, making it perfectly suitable for coffee brewing.

It’s also one of the lightest plastics available, with a density of around 0.9 g/cm³—lighter than water—yet it still offers solid rigidity and surface hardness. Its melting point is about 165°C, which easily handles brewing temperatures. It’s also highly resistant to most chemicals, meaning coffee oils and cleaning agents won’t damage it.

Structurally, the dripper consists of two main parts: the main body and an external support ring. The ring is designed to help the dripper sit on certain servers, but in my opinion, its diameter is a bit too small—it doesn’t fit standard carafes well. Luckily, I use a dual-scale setup, so I just place it directly on my scale. If you don’t have that setup, you can simply place the dripper directly on a server and skip the ring altogether (honestly, I find it pretty unnecessary).

Inside, the dripper features a smooth, ribless wall, and the body has a 40° angle from wall to base. These two elements are really the essence of the SOLO design. The wide opening angle means your coffee bed will be relatively shallow, which makes it much easier to quickly saturate during the bloom phase.

The ribless interior is designed to achieve zero bypass, and combined with the angled structure, it promotes a smooth and even extraction. The large single hole at the bottom ensures proper flow and uniform percolation.

To truly take advantage of these features, filter choice becomes extremely important. I went all in—buying a filter press tool and even splurging on Spanish FAST filters—just to push this dripper to its limits.

Here’s why: during my initial test brews, I used my usual Lyocell fast filters. But these wave-style filters have a curved, fluted edge, which means they don’t fully adhere to the dripper walls. That alone breaks the zero-bypass design. Sure, you can brew that way—but from my taste tests, the flavor difference is very noticeable.

So I strongly recommend using this dripper with a zero-bypass setup.

The key challenge is getting the filter to fully adhere to the walls. There are tutorials online showing how to fit traditional wave filters into the SOLO, but honestly, they’re not very practical—and some even require a second SOLO dripper. (Haha.)

The method goes like this: wet the filter first, then use another SOLO dripper to press it into shape. Before pressing, align the direction and give it a slight twist. Press straight down first, then gently rotate to lock in the shape. That’s how you get a proper fit.

Another important discovery: Lyocell filters don’t have enough structural support for such a large-bottom-hole design. During the mid-to-late stages of brewing, you’ll see noticeable sagging—sometimes even forming a hole. This makes the brew much harder to control.

I experienced this multiple times. Even when I managed to get the filter to fit well initially, it still sagged later on.

But here’s the surprising part—even those “messy” brews produced incredibly enjoyable coffee. The cups were balanced, sweet, and full-bodied. It really made me realize just how forgiving this dripper is.

After thinking it through, I decided to invest in a proper filter press tool and Spanish FAST filters. With those, you can achieve near-perfect adhesion and essentially eliminate bypass, ensuring that all the water passes through the coffee bed.

Of course, you’ll want to pair this with a slightly coarser grind.

And honestly, the Spanish FAST filters are worth the price. Their structural strength is outstanding—no matter how you brew, the bottom stays stable and smooth. You can brew with complete confidence. The adhesion to the dripper walls is also excellent, making the entire process much easier and more enjoyable.

Most importantly, when you achieve true zero bypass, the resulting cup is exceptional. The sweetness and balance are on another level. Even lighter, fruit-forward coffees gain a richer, cleaner body, with a smoother, more rounded mouthfeel.

It also significantly enhances the depth and layering of flavors in the cup—something that traditional V60-style drippers simply can’t replicate.

The Secret Behind Clear Coffee: How CLR CFF Made Coffee Completely Transparent

 Do you still remember CLR CFF, the colorless, crystal-clear coffee that went viral nearly a decade ago? I was lucky enough to actually try that “internet-famous” product back then. For so long, we all believed coffee could be reddish-brown, brown, or even red—but it never crossed our minds that coffee could exist as something completely transparent.

When CLR CFF was first released, it immediately caught the attention of coffee lovers. It became the world’s first colorless coffee drink, and its production process was always described in a vague, mysterious way—“made with methods never used before.” It sounded almost mythical, and no one ever seemed to crack the secret behind it. Today, the brand’s social media accounts have gone silent, its official website is no longer maintained, and similar products have essentially vanished. So how did they manage to make coffee completely clear? Let’s talk about this “mysterious” technology.

Simply put, the core idea is to keep the flavor and caffeine of the coffee while removing all substances that create color. The key technology behind this result is precise separation and recombination. Just like traditional coffee, the process starts with carefully selected beans that are roasted—usually lightly roasted to achieve a bright, fruity acidity while avoiding the heavy color and oils produced by dark roasts. Next comes the extraction stage, which is crucial for transparent coffee.

Cold brew is typically used to extract this type of colorless coffee. Using hot water would pull out more oils, acidic components, and suspended solids from the beans—substances that cause cloudiness and dark color. Cold brewing, on the other hand, gently extracts the volatile aroma compounds and caffeine while minimizing the release of pigments and oils. This means the initial coffee liquid is already much lighter in color compared to hot-brewed coffee.

The cold-brew concentrate then undergoes the second key step: a series of highly precise filtration processes. First comes ultrafiltration, which removes large molecules such as proteins, polysaccharides, and some pigments. Next is nanofiltration, capable of filtering out even smaller molecules, including most of the components responsible for color. After these two steps, the liquid undergoes reverse osmosis, which removes nearly everything except water molecules and the very smallest compounds. This process functions like a molecular-level sieve, leaving behind clear water, caffeine, and the aroma compounds that define flavor.

I remember that when I tasted this transparent coffee, if I had been blindfolded, I wouldn’t have known it wasn’t regular coffee. It had a refined and surprisingly full flavor, balanced and very similar to a typical cold brew. But with such extensive filtration, some volatile aroma compounds inevitably get lost. To solve this, manufacturers may use a technique similar to aroma recovery. During the early stages of extraction, they capture those volatile aromas and then reintroduce them back into the filtered, colorless liquid to ensure the final product still smells like coffee.

Finally, the processed clear coffee liquid, the recovered aromas, and any necessary components (possibly tiny amounts of natural flavorings to enhance taste) are blended and bottled. With all solids and oils removed, transparent coffee typically has very low acidity and an extremely clean, smooth mouthfeel. It was advertised as a zero-calorie or low-calorie beverage, and for people worried about coffee staining their teeth, its colorless nature made it stain-free. The refreshing taste also made it easy to mix with cocktails or sparkling water for unique “coffee-based” drinks—coffee flavor without coffee color, which naturally generated tons of buzz.

However, transparent coffee does have drawbacks. Its flavor is extremely simple—smooth and balanced, but thin, almost like “water with coffee flavor.” It’s also a highly processed beverage, much like how some people feel hesitant about decaf, believing it loses the soul of coffee and many of its natural qualities. But the biggest reason we rarely see CLR CFF or similar products today is the cost. The production process is extremely complex and expensive. Back in 2017, a 200 ml bottle of CLR CFF cost me nearly 80 RMB including shipping—far more expensive than a regular cup of coffee with a richer, more complex flavor.

Overall, I see CLR CFF as a fascinating achievement in food engineering—a product made through cold brew extraction, molecular-level filtration, and aroma management. But it was never destined to disrupt traditional coffee or become mainstream. Its disappearance from the market seems almost inevitable. In reality, products built on viral hype often become temporary trends. What truly stands the test of time are the simple, everyday coffees that people return to again and again.