Pen-plotting, what's this ?

Born in the 1960s, the pen plotter was one of the first machines able to turn digital graphics into marks on paper. Largely displaced by increasingly capable colour printers, it has found a new life among artists drawn to the physical, imperfect side of digital images.

A plotter does not reproduce an image as a printer does. It performs a drawing, line after line, in real time. The final result is affected by paper grain, ink flow, pen pressure, friction, humidity, vibration, and occasional failure.

A short history

A pen plotter, or tracing device, can be seen as an archaic technology from the earliest days of computer graphics.

In its simplest form, a two-axis mechanism drives a pen above a sheet of paper to trace vector graphics. Before graphical displays became commonplace, plotters were one of the few ways programmers could obtain a visual output from their code. Rather than displaying an image on a screen, the machine would physically draw it.

They were used by some of the earliest computer artists, such as Frieder Nake, Manfred Mohr, Vera Molnár, who explored the relationship between algorithms and visual art, sometimes developing or modifying their own machines in the process.

Plotters later became widespread tools in fields such as architecture, engineering and industrial design. By the 1980s, screens and raster printers had largely replaced plotters as a mainstream way of visualising computer graphics, although they continued to be used in specialised technical fields.

By the 2000s, computers and inkjet printers were capable of rendering almost anything in full colour with extraordinary precision and fidelity. Yet some programmers, artists and electronics tinkerers felt the urge to go the other way. Rather than pursuing ever more perfect digital images, they became interested in the imperfections of physical drawing and began building homemade XY machines from stepper motors, belts and scrap parts.

In 2014, Windell Oskay of Evil Mad Scientist Laboratories introduced a machine that would eventually become the Axidraw: a modern, accessible pen plotter that helped revive the practice of drawing vector graphics on paper using ordinary pens.

From oil painter to plotter artist

I first encountered the idea of a plotter in the 1980s; I was eight years old and had written my first graphic programs in Logo Turtle on Thomson TO7 at my mother's school's .

In truth, I never saw this "plotter" in action: a booklet mentioned that a teacher could borrow the turtle robot from the local education authority. I was fancying I would have drawn my programs on the floor on large sheets of paper : the dream !

Throughout my career, I've worked with a wide variety of unusual electronic interfaces, often having to invent the programs to control them. Never a plotter, though, because I had my solid, precise hand as a draftsman and painter.

Around 2020, I was already used to working with a CNC machine at home when my development studio took on a project to transform a large industrial CNC into a giant plotter. I started writing software capable of controlling different machine models to produce drawings.

The need to create test drawings led me to design SVG files.

I got carried away, became passionate about producing these generated images, to the point of an obsession that led me fully into generative art.

I quickly traded in the energy-guzzling industrial CNC plotter, to which I also had limited access, for a modest Axidraw A4 that fit on my desk. I continued developing the software and from then on produced plotter drawings every evening, launching tasks lasting several hours, falling asleep to the robotic sound of the servo motors and the pen hitting the paper, waking with a start when the din stopped, coming down from my mezzanine still half asleep to close the pen cap and observe the result of the job.

These experimental drawings, which I recorded in a sketchbook, became increasingly complex and required more and more advanced adjustments, so that only my plotter software could produce them perfectly.

These daily explorations involved the creation of grass.js, my founding algorithm, the refinement of my plotter technique and control software; and eventually The Oak Tree, the series that would become my first NFT a few months later.

In June of the same year, I purchased an Axidraw A3, then in November, I was probably the first customer to order an Axidraw A1, with which I drew Monoliths #000, the largest drawing I had ever plotted, made with the code that would become Garden, Monoliths.

The plotter defined my style

In every digital work I have produced since, the plotter has been there in some form.

A 2-axis plotter merely understands 2 instructions :
- lift/lower pen
- trace a straight line between point A and point B

An image intended to exist on paper through such machine must be constructed as a succession of such segments. For instance, to draw even a simple circle, the curve must be divided into tiny segments—small enough that the approximation disappears into the inked stroke and the irregularities of the paper.

As is often the case, what we might see as a constraint, a limitation of the tool, becomes a creative force.

By systematically restricting graphic elements to basic lines, thework acquired the consistency: a foundational rule from which a visual language could emerge.

Craftsmanship doesn't accept shortcuts

In the digital age, the plotter is not one of those technological objects that contribute to the race for precision, speed, and performance. Rather, it appears as a constraint that the artist imposes upon themselves to reintroduce imperfection, slowness, and humanity into their work. The plotter makes a generative image into something with a body..

Line by line, the plotter patiently follows the instructions it has been given, at a speed no faster than that of a human hand.
It's not uncommon for a plotter drawing to take several hours, or even several days.

Once the paper is positioned, the chosen marker is inserted into the machine, and the settings are adjusted, the job begins and the machine performs the score. Some projects are completed in one pass. Mine rarely are: I divide then into numerous layers, each with its own pen, ink, speed setting, and hours-long plotting time.

There are as many decision-making steps as there are layers in the drawing. Double passes, triple passes to perfect the density of a line. Mixing ink again, refilling cartridges, cleaning a clogged tip. Oftentimes, it requires going back to the program or writing an entirely new algorithm, or a plotter software feature, to try to correct a graphic result that isn't up to standard.

Sometimes, days of work on the plotter end in failure, with indelible ink mistakes that no amount of skill or artistic talent can erase. The ultimate decision-making can be to start over, like in this complex plot of Still life with meaning :

Pen-plotters aren't printers

I have often noticed confusion among my collectors when the term "print" is used.
While it is true that a plotter can be classified as a printing technique, alongside methods like etching or screen printing, the tool itself dictates fundamental differences.
A standard printer, such as the one we use to fulfill orders from our print store, is an inkjet machine capable of producing large-format works with remarkable precision and a perfect reproduction of the source digital image. This type of printer can reproduce any digital image—whether a photograph or a digital creation—onto paper in just minutes, delivering consistent results every time.

As we explained in this article, using a plotter is a lengthy process, fraught with uncertainty and happy accidents, where the artist remains involved at every stage. Each plot is an adventure, and the final outcome cannot be known in advance.
Furthermore, a plotter requires a file containing vector instructions (essentially a sequence of line segments) as input. This is a mathematical representation of a drawing (unlike the pixel grid, or bitmap, sent to a conventional printer).
To be "plotted," a drawing must first be "plottable"! It is for this reason, and thanks to this fundamental constraint, that the plotter so effectively extends the programmer's creative gesture. It is that very conversation, between the code and the pen's movement across the paper, that shows through in the final result.