Physicists Unravel the Fluid Dynamics Behind Dendritic Painting
Art and science have always had an intriguing relationship, with artists often employing scientific principles to create their masterpieces. One such technique is dendritic painting, a method that involves depositing mixtures of ink and rubbing alcohol onto paint spread on a substrate, resulting in intricate branching, tree-like patterns. Now, two physicists have delved into the underlying fluid dynamics behind this technique, shedding light on the science behind the art.
The findings of their study have been published in the Proceedings of the National Academy of Sciences Nexus. Co-author Eliot Fried from the Okinawa Institute of Science and Technology (OIST) in Japan explains, “Painters have often employed fluid mechanics to craft unique compositions. We have seen it with renowned artists like David Alfaro Siqueiros, Jackson Pollock, and Naoko Tosa. In our laboratory, we reproduce and study artistic techniques to understand how the characteristics of fluids influence the final outcome.”
Fried is part of a group of scientists fascinated by how artists utilize fluid dynamics in their work. Physicist Roberto Zenit from the National Autonomous University of Mexico has been studying the physics of fluids in artistic techniques for several years. His research has revealed that artists are “intuitive physicists,” using scientific principles to create timeless art.
One of the techniques explored by Zenit is the “accidental painting” technique used by Mexican muralist David Alfaro Siqueiros. This method involves pouring layers of paint on a horizontal surface and allowing whorls, blobs, and other shapes to form over time. The heavier liquid pushes through the lighter one, creating a classic instability. Zenit has also studied the “decalcomania technique” favored by artists like Max Ernst, Oscar Dominguez, and Remedios Varo. This technique involves painting a surface and covering it with a flexible sheet of plastic before ripping off the plastic, resulting in tree-like structures.
Another artist whose work has fascinated physicists is Jackson Pollock. Pollock’s famous dripping technique involved pouring paint onto a canvas laid flat on the floor. He used various tools such as sticks, knives, brushes, and even syringes to create his unique style. The controversy surrounding Pollock’s paintings lies in whether or not they exhibit evidence of fractal patterns. Fractals are complex geometric shapes that repeat infinitely at different scales.
In 2011, physicists examined Pollock’s use of a “coiling instability” in his paintings, which occurs when a viscous fluid folds onto itself like a coiling rope. They mathematically described this phenomenon, comparing it to pouring cold maple syrup on pancakes. However, a 2019 study found that Pollock actively avoided coiling instabilities in the majority of his traces. In 2023, researchers used reinforcement learning to exploit rather than suppress coiling instabilities, applying this method to direct ink writing for 3D and 4D printing.
Inspired by this prior research and contemporary artists like Naoko Tosa and Akiko Nakayama, Eliot Fried and San To Chan from OIST conducted their own study on dendritic painting. Nakayama creates dendritic paintings in real-time using multicolored inks mixed with rubbing alcohol. The artists exploit the underlying fluid dynamics to create unique shapes and textures.
The primary phenomenon at work in dendritic painting is the Marangoni effect, which is responsible for wine tears and the coffee ring effect. The Marangoni effect occurs when there is a difference in alcohol concentration between two liquids, creating a surface tension gradient that drives fluid flow. In dendritic painting, the expanding ink droplet shears the underlying acrylic paint layer, similar to shaking a ketchup bottle.
Fried and Chan conducted experiments using carbon black acrylic ink, acrylic resin, titanium white paint, and sugar syrup for control experiments. They found that the thickness of the paint layer and the concentration of the diluting medium and paint were crucial factors affecting fluid flow. The most refined fractals were achieved when the paint layer was less than half a millimeter thick. Using three parts diluting medium and one part paint produced detailed fractals, while higher paint concentrations resulted in less efficient spreading and fuzzier edges.
The researchers are now developing novel methods to analyze how the complexity of a painting evolves during its creation, hoping to uncover hidden structures in images of fluid flows. Fried explains that the physics behind dendritic painting is similar to how liquid travels in a porous medium like soil, known as percolation. Under a microscope, the mix of acrylic paint reveals a network of microscopic structures made of polymer molecules and pigments. The ink droplet finds its way through this network, following paths of least resistance that lead to the dendritic pattern.
The study by Fried and Chan provides valuable insights into the fluid dynamics behind dendritic painting, bridging the gap between art and science. By understanding the underlying physics, artists can further explore and manipulate
