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How to Watercolor Paint with a Robotic Drawing Machine: An Interview with Licia He

Posted by Michelle Chandra on

When I first started plotting my generative designs, I initially turned to Instagram to find other plotter artists. One of the first people I ended up following was Licia He who has tuned her Axidraw into creating stunning generative watercolor paintings. In this interview, Licia gives a breakdown on how she uses the Axidraw to make watercolor paintings of her generative art!

licia he nested grid painting watercolor with axidraw drawing machine experimental art

I am an avid fan of your work, but don't know much about your background and how you ended up creating watercolor plots! How did you get into making code art? 

Thanks, Michelle! I feel honored to join you for this interview.

I majored in art and computer science during my undergrad. My undergrad education was the perfect opportunity to work on digital art, but instead, I focused on traditional printmaking. I gradually started working on generative art during the early years of my doctoral program because I needed to create something, and not having access to a print shop or an art studio geared me towards something digital. I was greatly inspired by many generative artists. I started to create online art systems like this poker card generator, truchet pattern generator (desc, demo), and this puzzle called "hidden message" (description, demo). 

What led you to use your Axidraw pen plotter to create watercolor paintings?

I got into plotters because I attended a student competition that asked us to build a robot several years ago. My team decided to build a doodling robot, which made me realize how difficult it is to create a high-precision drawing robot. The following summer, I accidentally had access to an Axidraw during my internship. It was love at first try. I love the precision that it brings. The act of creating something physical is beautiful to me. When I finished my internship and returned to my doctoral program, I purchased my first Axidraw. 

Besides playing with more documented plotting tools such as pens and markers, the initial idea I had was to paint with eyeshadow instead of watercolor. I had some expired eyeshadow that I refuse to throw away, but painting with them is very time-consuming because their pigment concentration is low.  

licia he eyeshadow plotting with axidraw pen plotter

I wanted to try other mediums because I figured out the mechanism to reload the brush/pen automatically. I am an art supply enthusiast, so I wouldn't give up any opportunity to play with materials.      

What interests you when you are creating code art? What programming languages do you use, and what themes do you enjoy exploring in your code art?

When I am creating generative art, I focus on the rules that I am making and breaking. I find it exciting to turn simple rules into visual forms and to explore variations of these forms. Making art with code, just like creating with other mediums, is a way of self-expression. Currently, I am most excited about how simple geometric shapes can form visually complex results. I started making generative art with javascript (using d3.js) but gradually moved to python. 

licia he watercolor painting with axidraw pen plotter

What are your favorite watercolor paintings that you have created in the past year, and why do you like them?

My favorite paintings typically change with time. I usually like the latest work I have created. I think this happens partially because recent works represent my current views and feelings. Currently, I am in love with a rotation-themed group of paintings. In fact, I have been obsessed with this group of patterns for over a month. I kept tweaking the details and introducing variations. (e.g., several proof shots, painting process, a recent file ready to be plotted

licia he flower watercolor painting with pen plotter code art

But once in a while, there will be pieces that reserve a special place in my heart. For example, I am still very fond of a plant-inspired piece and a nested grid painting that I did earlier this year.

Your watercolor paintings marry the analog and digital beautifully especially with your use of color! What have you learned trying to translate your code art into watercolor paintings? 

There are undoubtedly many things that I have learned from my painting-with-plotter experience. For example, I discover the type of patterns, compositions, and elements that I would prefer in watercolor paintings. I have a preference for filled designs that display mathematical precision and randomness at the same time. Of course, my taste is not a fixed set of rules. Each painting I make contributes to the making and the breaking of these rules. 

licia he watercolor ink painting with pen plotter experimental code art

Another important thing I learned is to let go of some control. For example, I used to spend a lot of time picking the perfect color scheme. The spontaneity that comes with watercolor helped me to stay away from the perfectionism mindset. Because the digital pattern would usually look completely different from the finished painting, sometimes it becomes hard to predict the output. Therefore, the only option is to plot, observe, and experiment again, which I enjoy very much.

For those interested in the technical, can you share info on how you programmed the Axidraw to paint your designs? 

The central idea for plotting with paint is not as challenging as I imagined initially: there's a fixed location where you store the paint/ink, and you can instruct your machine to refill at that location by drawing a mark (e.g., a circle, a line, a dot) there.

(To demonstrate how this works, I have uploaded this file to Plotterfiles, which is a fantastic plotter art sharing platform developed by Maks Surguy)

licia he plotter file watercolor painting with axidraw pen plotter generative art

Therefore, to make a plotter painting, there are only two questions that I need to figure out: first, where do I place my paint/ink refill station? Second, when should I refill my brush? The first question is easy to answer: wherever I want. I placed my refill station on the edge of the plotter area. To ensure my refill station's location has a fixed location, I designed an 11x2 wooden template and glued five plastic cups. Whenever I need to refill, I draw a circle on where a plastic cup sits. 

The second question might require some programming. Essentially, I need a tool to break down the SVG paths into chunks that are shorter than a certain distance. I call this the "refill distance." Different brushes would have different refill distances. To make this happen, my patterns only consist of the <path> element because all other elements like <circle> <rectangle> or <line> can be converted to <path> elements. There might be tools out there that do this, but I wrote my own converter. The next chunk of code calculates the distance of any <path> element and breaks it down to short chunks. A <path> element in SVG actually contains many commands such as Line Command (L,l), "Arc Command (A,a), and Cubic Bezier Command (C,c). Calculating line distance is probably the most straightforward option. Therefore, I wrote converters that "translate" other commands into line commands. For example, I would approximate a bezier curve with tiny lines (e.g., 3-5px). 

With these two questions figured out, my general programming pipeline looks like this:

  1. Getting inspiration, making physical sketches
  2. Writing the algorithm, which generates a list of <path> elements. In practice, I usually make a list of points instead of assembling the points into a <path> element. 
  3. Break down <path> elements that are longer than the refill distance, so that each child <path> would be shorter than the refill distance. 
  4. Between each processed <path> element, add an instruction to refill (i.e., a circle at the refill location).

Because my paintings are getting increasingly complex, opening them in Inkscape could take some time. To avoid that loading time, I directly export my patterns into python scripts (Thanks to the awesome Axidraw API:pyaxidraw). I initially chose to use a circle as the instruction mark because I need to stir the watercolor to prevent sinking pigments. But if I am painting with ink or more evenly distributed paint (like liquid watercolor), I can simplify the refill instruction into a dot (pen_down and pen_up).  

licia he watercolor painting with axidraw pen plotter code artwork

Do you have any advice for folks interested in watercolor painting with a pen plotter? 

I would recommend everyone try it because it is such an amazing and unique art-creating experience. But at the same time, painting with watercolor is naturally messier than using pen/markers. You will want to protect your workspace because paint can get to unexpected places without warning. I cover my table and wall with paper and board, but still see paint splashes on unwanted locations (e.g., the computer that I use to control the plotter). I also recommend getting some good hand cleanser and a painting apron if you want to be extra careful. 

licia he axidraw plotter setup for watercolor plotting

It is also essential to raise your plotter at a height that is impossible to be flooded. In addition to the four-color refill station, I also have a spot reserved for brush cleaning, where I place a water tray. I certainly do not want my plotter soaked in the occasional accidents where the tray is knocked over. Therefore, I use wooden blocks to raise my plotters to ensure that they are not affected by these accidents.

Another issue I cannot avoid is the constant need for motor replacement. Because I am using a tiny brush, the servo motor needs to perform the pen up and pen down operations quite frequently. As a result, my servo motors run out very quickly. Depending on the servo motor's quality, there were weeks when I was replacing motors every other day. It's not hard to replace them, but it is certainly not enjoyable either.       

Overall, just be an experimentalist and play with it (and order enough servo motors). 

What watercolor inks do you enjoy using and why?

I love watercolor paints that I made by myself. Handmade watercolor might behave slightly differently compared to manufactured ones because hand mulling might result in bigger particle sizes. Therefore, handmade watercolor might produce interesting granulation effects.

licia he watercolor ink painting with axidraw pen plotter red and purple and blue

Besides handmade watercolor, I like to use fountain pen inks. I have recently used more ink and liquid watercolor than watercolor (in pans or tubes) because the ink does not need to be stirred during the painting process. I also do not need to wait for it to rewet. I can directly use ink from the bottle. Because it is so convenient, I accumulated an ink collection recently. I am still new to the fountain pen ink world, but so far, I am fond of ink from Diamine and Organic Studio because of their color selections and the sheening effect that some of their products create.

Are there any other projects you are working on at the moment?

I am fortunate that my current research overlaps with my art interests. In my research projects, I am looking for ways to support creativity and innovation in the designing and making of physical crafts. The plotter-based punch needle embroidery project that I released this year is an example of my projects. 

Where can people find you online to learn more? Thanks again for sharing insights into your work!

I am very active on Instagram because of my plotters. It is a place where I put daily updates about my plotter journey. Because I also need a place to share the finished art pieces, I have recently started using Twitter. My website is the official place for my art, but new paintings will take some processing time before they appear on it.

Thanks, Michelle. I am delighted to have this chance to share my work with you.

*All images provided courtesy of Licia He

All Generative Art, All the Time

But what if you want to learn more?! Check out these additional blog posts:


michelle chandra of dirt alley design
Dirt Alley Design was founded just off a dirt alley in San Francisco in December of 2016 by artist Michelle Chandra. Inspired by the beauty of street grids, Michelle invented maze maps in which she transforms street grids into mazes. In 2019, she began a new project - geometry art created with code and drawn with a pen plotter. Follow her on Instagram and Twitter @dirtalleydesign where she posts new spirograph designs daily 

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