What do dendritic plaque and “wine tears” have in common?

Dendritic painting is an artistic technique that involves depositing a mixture of ink and rubbing alcohol onto paint spread over a substrate, producing branching, tree-like patterns. Two physicists have now analyzed the fundamental fluid dynamics at work to create those complex shapes and patterns, and describe their findings in New paper Published in Proceedings of the National Academy of Sciences Nexus.

“Painters have often used fluid mechanics to craft unique compositions,” said co-author Elliott Fried Okinawa Institute of Science and Technology (OIST) in Japan. “We've seen that with [Mexican muralist] David Alfaro Siqueiros, Jackson Pollock, and Naoko Tosa, to name a few. In our laboratory, we reproduce and study technical techniques to understand how fluid properties affect the final result.”

Fried is one of many scholars interested in how artists exploit fluid dynamics in their work. For example, Roberto Zenit, a physicist at the National Autonomous University of Mexico, has been studying the physics of fluids operating in those technologies for several years, and concluded that artists were “intuitive physicists,” using science to create timeless art—including Siqueiros' “transverse drawing” technique.

This technique involves pouring layers of paint onto a horizontal surface and letting flowers, blobs, and other shapes form over time, as a thicker liquid is layered on top of a lighter liquid. This creates Classic instability Because the heavier liquid will push through the lighter liquid. Zelnit also studied the “decalcomania technique” favored by artists such as Max Ernst, Oscar Dominguez, and Remedios Varo, which involves painting a surface and covering it with a flexible layer of plastic, before tearing up the plastic and forming tree-like structures. .

As for Pollock, he early used the “flying string” or “flying catenary” technique before mastering pointillism techniques. The paint forms various sticky threads that are thrown onto a vertical canvas. The dripping technique involves laying a flat cloth on the floor and then pouring paint over it. Sometimes he poured it straight from the can. Sometimes he used a stick, a knife, or a brush; Sometimes he used a syringe. The artist usually moves “rhythmically” around the canvas as he works. His method has fascinated physicists for a long time, as evidenced by… Surrounding controversy The question of whether Pollock's paintings show evidence or not Of fractal patterns.

In 2011, physicists examined Pollock's use of… “Winding instability” In his paintings, he mathematically describes how a viscous fluid folds in on itself like a coiled rope – just like… Pour in cold maple syrup On pancakes. a 2019 study He found that the vast majority of Pollock's effects were produced because the artist effectively avoided the instability of coiling. In 2023, researchers Uses reinforcement learning To exploit spin instability rather than suppress it, and apply this method to direct inking, a versatile method for 3D and 4D printing. They even decorated the cookie with chocolate syrup to prove the feasibility of their new approach.

Fried and co-author San Tou-chan, also at OIST, drew inspiration from this earlier work, as well as contemporary artists like Tosa — known for evocative drawing with sound waves and capturing how he moves on high-speed video — and Akiko Nakayama. Nakayama works with multicolored inks mixed with rubbing alcohol to create dendritic paintings in real time, exploiting fundamental fluid dynamics to create unique shapes and textures. “Dendritic painting poses an interesting but non-trivial problem involving the evaporation, diffusion and pattern formation of thin liquid films over rheologically complex media,” the authors wrote.