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 Today, the brand’s social media accounts have gone silent, its official website is no longer maintained, and similar products have essentially vanished.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.