The coffee stain effect, a phenomenon well-known in both physics and everyday life, occurs when a liquid containing particles evaporates, leaving behind a dark edge.

Previous studies at the University of Twente highlighted that this effect, caused by an "avalanche" of particles moving to the outer edges, is undesirable in applications such as inkjet and 3D printing.

However, recent research, as published in the Proceedings of the National Academy of Sciences (PNAS), reveals that modifying surfaces with an oily layer can effectively inhibit this effect.

Understanding the Particle Avalanche:

The University of Twente's research group previously demonstrated that, during the evaporation of a particle-laden droplet, particles gradually migrate toward the droplet's edge.

Initially, this motion is slow and regular, but as the droplet loses height due to evaporation, particles rush towards the edge in a disorderly manner, akin to an avalanche.

The diameter of the droplet plays a crucial role in initiating this movement. Scientists seek to prevent this occurrence, as many applications require even particle distribution. The latest findings propose that oily surfaces provide a solution.

Utilizing Oily Surfaces to Inhibit the Effect:

The introduction of an oily layer confining the droplets proves effective in preventing unwanted particle movement. This non-evaporating oil layer impedes rapid water evaporation at the droplet's edge, thus restraining particle migration. Interestingly, particles can even move inward from the droplet's edge.

When all the liquid evaporates, the particles evenly cover the surface, eliminating the formation of black rings around the edges. Moreover, the researchers observed an additional effect: a complete layer of oil covering the droplets, resulting in the formation of nano-eyes, or "coffee eyes."

Adding surfactant to the droplets allows control over the deposition pattern, from espresso rings to even distribution, catering to specific applications like nanoparticle assembly.

Cultivating Reasonable Coffee Consumption Habits

Opting for a Coffee Cup with a Lid:

Choosing a coffee cup with a lid effectively reduces the likelihood of spills, minimizing the occurrence of the coffee stain effect. The covered design not only prevents spills but also maintains the coffee's temperature, enhancing the overall coffee-drinking experience.

Moderating Drinking Speed:

Controlling the drinking speed during coffee consumption can prevent splashing caused by excessive speed. Savoring coffee slowly allows individuals to appreciate the aroma and taste while reducing the chances of coffee stains.

Utilizing a Coffee Dripper or Filter:

For those who prefer brewing their coffee, using a coffee dripper or filter proves to be an excellent option. This approach avoids direct contact with coffee grounds, minimizes spills and contributes to a neater coffee experience.

Effective Cleaning Methods

Promptly Wiping Coffee Stains:

Addressing coffee stains promptly is crucial to prevent them from penetrating surfaces or clothing fibers, making future cleaning more challenging. Gently wiping the stains with a damp paper towel or cleaning cloth can swiftly remove coffee stains.

Choosing Professional Cleaners:

Selecting professional cleaners designed for specific surfaces, such as furniture or floors, yields more effective results in dealing with coffee stains. Reading and following the instructions carefully ensures correct usage, preventing any potential damage to furniture or items.

Regular Deep Cleaning:

In addition to daily cleaning, regularly conducting deep cleaning sessions is essential to avoid the coffee stain effect. Thoroughly cleaning furniture, walls, and other potentially affected areas maintains a clean and hygienic overall environment.

By incorporating reasonable coffee consumption habits and effective cleaning methods, individuals can effortlessly sidestep the inconveniences of the coffee stain effect, creating a fresh and tidy coffee lifestyle.

While relishing the pleasures of delicious coffee, let us collectively prioritize the protection of our surroundings, ensuring a refreshing and enjoyable life experience.