Michelangelo, who painted The Creation of the Heavens and the Earth on the Sistine Chapel ceiling about 500 years ago, had to wrestle throughout the work with paint dripping onto his face. This phenomenon of liquids pouring downward due to gravity has long been regarded as a natural law that is hard to avoid. But a Korean research team has presented a way to control "gravitational instability," the fundamental cause of this problem.
A research team led by Kim Hyeong-su, a professor in the Department of Mechanical Engineering at Korea Advanced Institute of Science and Technology (KAIST), said on the 12th that it developed a technique that suppresses gravity-induced instability of liquids by mixing a small amount of volatile liquid. The results were published online in January in the international journal Advanced Science and were selected as the cover article.
The team proposed mixing a small amount of a volatile component into an inverted liquid. When the volatile liquid evaporates, a concentration difference arises at the liquid surface, and as a result the distribution of surface tension also changes. Surface tension is the force by which a liquid surface pulls itself inward, and it is also why a water droplet maintains a rounded shape.
The researchers demonstrated through experiments and theory that the side with higher surface tension pulls the side with lower surface tension, creating a flow along the liquid surface, and that this flow holds the liquid that would otherwise fall downward. In other words, the surface flow generated by the liquid itself suppresses gravity-induced instability.
The study has strong potential for use in industry as well. In precision coating, printing, and deposition processes, it could enable thinner and more uniform liquid films, and allow stable application even on inclined surfaces. In particular, it is expected to help improve quality in advanced manufacturing processes that require precise handling of liquids.
Kim Hyeong-su said, "This study is significant in that it shows the potential to actively control gravitational instability without any external energy," adding, "Beyond coating, printing, and deposition technologies, it could also extend to fluid control in space environments."
References
Advanced Science (2026), DOI: https://doi.org/10.1002/advs.202520343