So what's the difference between plotted and printed artwork?

A common source of confusion that I experience when posting my artwork on social media is: why? Why use a plotter when you could use a printer? It's slower. Less exact. More expensive. It fails, far too often. Inkjet printers became ubiquitous in the 1980s because they solved nearly all of these problems. So why are artists obsessed with pen plotters?

I'll be upfront, I'm going to list all of the reasons that I love pen plotters in this article. That's not to say that they're superior, though. Like any tool, they have their place amongst many different printing technologies and come with their own benefits and drawbacks.

Pen plotters are somewhat like 3D printers. They move in X/Y space and typically have a pen lift mechanism. Attached to their arm can be any number of drawing instruments, from pens to pencils, brushes to pastels, and even drill bits to scratch glass.

Printers (we'll focus on inkjet for this article) blast tiny ink particles into paper and can seamlessly mix them to create a range of visually distinct hues and tones. In the art world, they're commonly used to make Giclée prints, which are essentially just archival, fine art prints.

Original Art vs. a Reproduction

Professional quality inkjet printers can do a fantastic job reproducing what an artist sees on screen. Artists like Zach Liberman use them to create beautiful reproductions of digitally native artworks.

The keyword here, though, is reproduction. A printer isn't capable of mixing pigments the same way an artist mixes paints on a palette. It turns out, computers aren't very good at it either. Computer scientists and artists have been attempting to replicate the physical properties of color mixing through approaches such as the theoretical Kubelka-Munk equation for some time now, with limited applicable results for digital artists and creators.

I say this not to bash the RGB model that most digital artists are familiar with, hell, I use it all of the time myself when creating art for screens. It's just, when you're going for realism in color, nothing quite beats the real thing.

Check out spectral.js for the best code-based implementation of the K-M equations that I've encountered.

Bottom line, when a print is produced, there is no emergence of color occurring; it's just an approximation of the pixel coloration in a digital file. Under the hood, your inkjet printer is using a sophisticated technique of subtractive color mixing to trick your eyes into seeing a spectrum of colors with only CMYK pigments.

Furthermore, It's beholden to whether the source material is a scan, a photograph, a digital painting, or an HTML canvas to get physically accurate results. If the source is a digital file, the chances that the colors are in any way physically accurate are unlikely. And maybe that's fine, depending on the artist's intent.

Plotters do not force an artist to use a specific color space or inkjet type. In fact, it's a non-factor. They only accept instructions in G-code. There's no raster source to pull pixel colors from. Instead, you, as the artist, must choose what drawing instrument to equip the plotter with. You can blend paints with watercolor, smear pastels together, and overlap inks to watch them subtly mix. The results are often unpredictable, and plotter artists may not know what they're going to create until it's finished.

Limitations with white ink

Most Inkjet printers aren't equipped with white ink. Printing numerous images with a black background will be pretty expensive because the printer is going to lay down copious amounts of black pigment on a piece of white paper.

With a pen plotter, it's as simple as buying some black paper and a white gel pen.

Media Size

Both large-format inkjet printers and pen plotters can get rather costly. In terms of cost-to-size ratios, though, I'd have to give the edge to my Nextdraw 2234, which can create artworks up to 22"x34". Without adjustments, it can also draw on tiny areas, business cards, or smaller.

Space matters, and printers have a minor advantage here, though, as large-format machines have a smaller footprint than plotters. They often take up entire tables due to their unwieldy arm.

Vintage plotters do exist in this standing format, and artists have restored them to create modern works of art.

A nice fit for generative workflows

Both printers and plotters are fully capable of producing generative art. Subjectively speaking, though, it is something special to make generative drawings. The imperfections present in pen-to-paper works complement the randomness inherent in the art. Staying in a vector art context, stripped down to purely linework, is an interesting artistic constraint.

I often iterate on a new artwork by drawing it on cheap printer paper or in sketchbooks. I'm looking for how the work feels when I see it, and I'm also making sure that it doesn't hit material limitations, like ripping through a sheet of paper because a pen glides over the same point too many times. I then go back to my IDE and make some code tweaks.

Frankly, it's really fun.

Obviously, everyone will have a different opinion on this. I know artists who love to nerd out at digital print studios, refining their colors to get results that look stunning to the naked eye. They experiment with the balance of CMYK values, printing swatches, and tests until they achieve outstanding fine art prints.

The same goes for the admittedly smaller subset of digital artists who create risographs, screen prints, intaglio, thermal printers, and other less common processes. (Okay, this sounds amazingly fun too!)

It wasn't until I got my first pen plotter in 2019 that I began to bond with the physicality of art making. The nuances of different inks and paper types. How much cotton was present? What about the texture? Hot or cold press? My art practices always revolved around a screen, and the pen plotter gave me an entirely new world of variables to explore. This was a breath of fresh air to my practice. I began going to as many art supply shops as I could find, and sought out ones wherever I traveled. Framing became an important consideration, and I revised my vision of the artwork to how it would appear mounted on a gallery wall. I began hoarding inks and swatching them for reference, looking for interesting characteristics such as sheening and shading. Since I now had all of these pens and inks, I started writing more, which has improved my mental health and given fresh life to my withered handwriting skills.

The drawbacks

I'd be remiss not to mention some of the drawbacks of pen plotters. There are many good reasons that nearly every commercial printing studio, design house, and architecture firm has abandoned the pen plotter as their tool of choice.

It's relatively slow, comparatively.

In a race vs. a human hand, the plotter has an edge in both speed and precision. Against even a basic Inkjet printer, though, a pen plotter is many orders of magnitude slower. I routinely create artworks that take 12+ hours to draw via the machine. The slow process severely limits the sizes of my editions - I simply can't do unlimited runs of artworks.

Multi-color processes aren't trivial.

Plotting something with multiple colors is tricky. If using pens, you must change inks. If using paint, you must clean and resaturate brushes. For example, I love the bold pop of Posca markers, but since they must be occasionally primed by shaking the body, there isn't a great workflow for plotter art.

Oftentimes, addressing these limitations is a manual process. Other issues arise, too. Removing items from the plotter arm is likely to cause misalignments, which will be apparent in the artwork.

I ended up designing a 3D printed holder to address my alignment issues, but I still have to manually switch pens for each pass of a color in a drawing.

Recently, I had the chance to compare a plotted version of my artwork to a professional-quality print from a reputable shop, and I was frankly blown away at the quality of the print. The printed resolution was exceptional, and details were sharp down to the sub-millimeter. The color was excellent, better than I could have imagined.

I offer both original drawings and printed reproductions of digital artworks to collectors because each medium has its benefits and drawbacks. My pen plotter studio simply can't compete with the volume of a professional print studio, and that's okay. I like the slower, more thoughtful workflow for many of the artworks I chose to produce.