It’s possible that I shall make an ass of myself. But in that case one can always get out of it with a little dialectic. I have, of course, so worded my proposition as to be right either way (K.Marx, Letter to F.Engels on the Indian Mutiny)
Wednesday, March 06, 2024
Beyond the ink: Painting with physics
Scientifically-proven suggestions for crafting a masterpiece.
Falling from the tip of a brush suspended in mid-air, an ink droplet touches a painted surface and blossoms into a masterpiece of ever-changing beauty. It weaves a tapestry of intricate, evolving patterns. Some of them resemble branching snowflakes, thunderbolts or neurons, whispering the unique expression of the artist's vision.
Okinawa Institute of Science and Technology (OIST) researchers set out to analyse the physical principles of this fascinating technique, known as dendritic painting. They took inspiration from the artwork of Japanese media artist, Akiko Nakayama. During her live painting performances, she applies colourful droplets of acrylic ink mixed with alcohol atop a flat surface coated with a layer of acrylic paint. Beautiful fractals – tree-like geometrical shapes that repeat at different scales and are often found in nature – appear before the eyes of the audience. This is a captivating art form driven by creativity, but also by the physics of fluid dynamics.
“I have a deep admiration for scientists, such as Ukichiro Nakaya and Torahiko Terada, who made remarkable contributions to both science and art. I was very happy to be contacted by OIST physicist Chan San To. I am envious of his ability ‘to dialogue’ with the dendritic patterns, observing how they change shape in response to different approaches. Hearing this secret conversation was delightful,” explains Nakayama.
“Painters have often employed fluid mechanics to craft unique compositions. We have seen it with David Alfaro Siqueiros, Jackson Pollock, and Naoko Tosa, just to name a few. In our laboratory, we reproduce and study artistic techniques, to understand how the characteristics of the fluids influence the final outcome,” says OIST Professor Eliot Fried of OIST’s Mechanics and Materials Unit, who likes looking at dendritic paintings from artistic and scientific angles.
In dendritic painting, the droplets made of ink and alcohol experience various forces. One of them is surface tension – the force that makes rain droplets spherical in shape, and allows leaves to float on the surface of a pond. In particular, as alcohol evaporates faster than water, it alters the surface tension of the droplet. Fluid molecules tend to be pulled towards the droplet rim, which has higher surface tension compared to its centre. This is called the Marangoni effect and is the same phenomenon responsible for the formation of wine tears – the droplets or streaks of wine that form on the inside of a wine glass after swirling or tilting.
Secondly, the underlying paint layer also plays an important part in this artistic technique. Dr. Chan tested various types of liquids. For fractals to emerge, the liquid must be a fluid that decreases in viscosity under shear strain, meaning it has to behave somewhat like ketchup. It's common knowledge that it's hard to get ketchup out of the bottle unless you shake it. This happens because ketchup's viscosity changes depending on shear strain. When you shake the bottle, the ketchup becomes less viscous, making it easier to pour it onto your dish. How is this applied to dendritic painting?
“In dendritic painting, the expanding ink droplet shears the underlying acrylic paint layer. It is not as strong as the shaking of a ketchup bottle, but it is still a form of shear strain. As with ketchup, the more stress there is, the easier it is for the ink droplets to flow,” explains Dr. Chan.
“We also showed that the physics behind this dendritic painting technique is similar to how liquid travels in a porous medium, such as soil. If you were to look at the mix of acrylic paint under the microscope, you would see a network of microscopic structures made of polymer molecules and pigments. The ink droplet tends to find its way through this underlying network, travelling through paths of least resistance, that leads to the dendritic pattern,” adds Prof. Fried.
Each dendritic print is one-of-a-kind, but there are at least two key aspects that artists can take into consideration to control the outcome of dendritic painting. The first and most important factor is the thickness of the paint layer spread on the surface. Dr. Chan observed that well-refined fractals appear with paint layer thinner than a half millimetre.
The second factor to experiment with is the concentration of diluting medium and paint in this paint layer. Dr. Chan obtained the most detailed fractals using three parts diluting medium and one part paint, or two parts diluting medium and one part paint. If the concentration of paint is higher, the droplet cannot spread well. Conversely, if the concentration of paint is lower, fuzzy edges will form.
This is not the first science-meets-art project that members of the Mechanics and Materials Unit have embarked on. For example, they designed and installed a mobile sculpture on the OIST campus. The sculpture exemplifies a family of mechanical devices, called Möbius kaleidocycles, invented in the Unit, which may offer guidelines for designing chemical compounds with novel electronic properties.
Currently, Dr. Chan is also developing novel methods of analysing how the complexity of a sketch or painting evolves during its creation. He and Prof. Fried are optimistic that these methods might be applied to uncover hidden structures in experimentally captured or numerically generated images of flowing fluids.
“Why should we confine science to just technological progress?” wonders Dr. Chan. “I like exploring its potential to drive artistic innovation as well. I do digital art, but I really admire traditional artists. I sincerely invite them to experiment with various materials and reach out to us if they're interested in collaborating and exploring the physics hidden within their artwork.”
Instructions to create dendritic painting at home
Everybody can have fun creating dendritic paintings. The materials needed include a non-absorbent surface (glass, synthetic paper, ceramics, etc.), a brush, a hairbrush, rubbing alcohol (iso-propyl alcohol), acrylic ink, acrylic paint and pouring medium.
Dilute one part of acrylic paint to two or three parts of pouring medium, or test other ratios to see how the result changes
Apply this to the non-absorbent surface uniformly using a hairbrush. OIST physicists have found out that the thickness of the paint affects the result. For the best fractals, a layer of paint thinner than half millimetre is recommended.
Mix rubbing alcohol with acrylic ink. The density of the ink may differ for different brands: have a try mixing alcohol and ink in different ratios
When the white paint is still wet (hasn’t dried yet), apply a droplet of the ink with alcohol mix using a brush or another tool, such as a bamboo stick or a toothpick.
Enjoy your masterpiece as it develops before your eyes.
Snapshots of the ink droplets containing 50 vol% alcohol (isopropanol) as they spread on a surface coated with 400 μm-thick acrylic paint with different paint concentrations (11%, 20% and 33%), captured over approximately 40 seconds. The images on the rightmost column show the zoomed-in views of the droplet edges. Higher paint concentration leads to increasingly refined and fractal-like droplet edges.
Images courtesy of Akiko Nakayama.
Fractal-like branches created with dendritic painting.
Researchers built a model that can predict with 73.5% accuracy when a person will experience aesthetic chills: shivers, goosebumps, or a feeling of cold down the neck or spine elicited by aesthetic stimuli, such as beautiful music or an inspirational speech. Felix Schoeller and colleagues surveyed 2,937 people from Southern California, through an online platform, gathering data on their personalities, demographic backgrounds, and emotional state. The authors then exposed survey respondents to 40 emotion-evoking audiovisual clips sourced from social media, selected because commenters had reported experiencing aesthetic chills while watching and listening. The clips included choral performances, a commencement speech by a minister, readings of poems by Charles Bukowski and Mary Oliver, pop songs by Radiohead and Sigur Rós, and scenes from the films Hunger Games and Everything Everywhere All At Once, along with many others. The authors then built a model that identified demographic, psychological, and contextual factors that would predict whether a given person would experience aesthetic chills when watching or listening to a clip. People who reported being alert and in a good mood were more likely to feel chills than those who were tired or in a bad mood. Other factors that correlated with high probabilities of experiencing chills were being 35–44 years old, being male, being a Democrat, and having a graduate degree. Psychological characteristics such as extraversion and conscientiousness were also predictive of experiencing chills, as were high scores on specialized psychological scales that measure a person’s propensity to be emotionally moved (the Kama Muta Frequency Scale) and absorbed in the moment (the Modified Tellegen Absorption Scale). According to the authors, additional research into how emotional experiences are shaped by psychological, demographic, and cultural variables could eventually inform the use of aesthetic chills as a non-pharmaceutical treatment for affective disorders such as depression.
Examples of goosebump-inducing stimuli are available at the project website: http://chillsdb.com.
JOURNAL
PNAS Nexus
ARTICLE TITLE
Predicting individual differences in peak emotional response
Text-to-image generative AI systems like Midjourney, Stable Diffusion, and DALL-E can produce images based on text prompts that, had they been produced by humans, would plausibly be judged as “creative.” Some artists have argued that these programs are a threat to human creativity. If AI comes to be relied on to produce most new visual works, drawing on what has been done before, creative progress could stagnate. Eric Zhou and Dokyun “DK” Lee investigated the impact of text-to-image AI tools on human creativity, seeking to understand if these tools would make the human artists less or more creative. The authors examined art made with and without AI on an online art-sharing platform. Artists who adopted AI showed increased productivity, compared to their pre-AI pace, and adopters tended to see an increase in favorable responses to their work on the platform after adopting AI. While artists who used AI showed decreasing average novelty over time as compared to controls, both in terms of the content of their images as well as pixel-level stylistic elements, peak content novelty among AI adopters is marginally increasing over time, suggesting an expanding creative space but with inefficiencies. Still, artists of all levels of creative ability are evaluated more favorably after adopting AI if they successfully explore new concepts but are generally penalized for using AI for exploring novel visual styles. According to the authors, this result hints at the potential complementarity between human ideation and filtering abilities as the core expressions of creativity in a text-to-image workflow, thus giving rise to a phenomenon they term as “generative synesthesia” – the harmony of human idea exploration and AI visual exploitation to discover new creative workflows.
JOURNAL
PNAS Nexus
ARTICLE TITLE
Generative artificial intelligence, human creativity, and art
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