In 2014, Mathew Beebe published something he called the Ultimate Filament Colorer on Thingiverse. It’s a technique of colouring plastic filament by passing it through the ink sponge inside a Sharpie marker before it feeds into the hotend of a 3D printer. The pigment mixes with the plastic inside the hotend, producing a permanent colour that doesn’t rub off.

If you want to get in on this technique, I wrote a step-by-step guide to help you out.

When ‘clear’ plastic is coloured, the result is generally the same colour as the Sharpie was. However, no one has documented the colours that result when opaque white plastic is coloured. The answer is that it creates pastel colours (Fig. 1)! In this article, I tested all the Sharpies I could find and documented their final printed colour.

Figure 1. Soma Cube pieces printed with Sharpie-coloured filament. Don't they look like delicious candy? The Sharpie colours used for these prints are the ones listed in Don't they look like delicious candy? The Sharpie colours used for these prints are the ones listed in my recommended palette later in this article (plus the uncoloured white filament).

Why colour filament?

It’s a good question. Why make your own coloured filament when you can just buy the stuff?

In short, there are three reasons:

Space. You need to store all that filament somewhere and keep it cool and dry. Waste. You end up with lots of open spools that need to be used up. Consistency.

That last point is the big one for me. Filaments from different manufacturers have different temperature profiles. Within a manufacturer’s line, every colour also has its own temperature profile — it might want a hotter first-layer temperature, for example, or it might start stringing at a lower temperature. And due to variations in the manufacturing process, each spool will have a slightly different average filament diameter. You would normally tweak your settings and find a compromise for all of the filaments you want to use, but if you use a single type of white filament and colour it on demand, you don’t have to.

The documentation process

I designed a Sharpie holder for this job (Fig. 2). Its most important function is to hold the Sharpie vertically above my printer’s extruder so that the filament has a straight line through the Sharpie and into the hotend, reducing friction and dragging. By printing each Sharpie’s holder using filament coloured by that same Sharpie, I can also use these prints as a colour reference in the future.

Figure 2. A set of Sharpies in the holders they helped create. The caps are covering the holes drilled into the bottom of the markers, while the holes at the bottom of the holders are sealed with tape.

Sharpies, annoyingly, are not labelled with their colour or even a colour code. I have therefore used Cheryl Shireman’s Sharpie colour reference diagrams to find both the name of the colour and the colour of its cap — Cheryl’s photos are somehow a truer reproduction of the cap colours than the photos on Sharpie’s own website.

I tried to photograph the final prints but I found it really difficult to represent their colours accurately. Instead, I did my best to mix the colour in GIMP’s colour picker while holding the finished print against my screen and under a strong white light. This was much more dependable.

The filament I used for all of these prints was Bilby3D white opaque PLA. It’s advertised as

Pure, bright white (not cream in colour).

Which makes it a nice base for this research. I printed it at 200 °C on alcohol-cleaned blue tape.

The results

GORGEOUS PASTELS OH MY GOSH

I have been wanting to print in pastels since forever, so this is great!

Standard Cap colour

Printed colour

Sky Blue

#e8fffc Turquoise #bbffdd Lime Green

#bafcc2 Green #71e8dd Pink #ffe6cd Magenta #ffd3ce Berry #fbc6d2 Purple #ffc8fa Black #e8e8e8 Orange #fffca2 Red #fa8d54 Electro Pop Cap colour

Printed colour

Ultra Violet

#fffdbd Nano Blue #94ffe4 Optic Orange

#ffd2b8 Techno Blue #9aeaf1 Electric Pink #f3ecf3



Floral Colours Cap colour

Printed colour

Pink

Off-white Sky Blue Off-white Peach

Off-white Lilac Off-white Mint Off-white Boysenberry Off-white Neon Cap colour

Printed colour

Neon Blue

#aff7f6

(Fluorescent) Neon Pink #ffe5f2 Neon Yellow

#f3ff9e Neon Orange #ffefc4



Metallic Cap colour

Printed colour

Gold Metallic

#c4d8db Silver Metallic #dff7fa







Discussion

Pastels, yes! It sure saves me from importing some of Faberdashery’s great pastel filaments.

Limited colour range

You’ve probably noticed a few oddities, like how some Sharpies produce very similar colours (Turquoise/Lime Green, and Pink/Magenta/Berry). I was also very surprised that none of the Sharpies produced a clean primary colour. Even Red Sharpie created an orange print when I expected it to just dilute and turn pink. I suppose these colour changes come down to the formulation, so markers from other manufacturers should have different formulations and produce their own particular colours.

Also note that all of the Floral Colours markers (the ones that came as pastels to begin with) produced so little colour in the final print that I could barely differentiate them from each other. It seems that the stronger the colour of the Sharpie, the better the printed result.

Desi’s recommended palette

Because so many of the Sharpies produce nearly-identical printed colours, we can omit most of them and just buy a few specific ones to form a pastel palette. Here are the ones I’ve settled with.

The palette of Sharpie colours that I use for printing. The palette is grouped into major colours (yellow, orange, blue, green, purple, and pink). Where possible, each major colour has a darker and lighter shade for subtle two-tone printing.

Cap colour

Printed colour

Orange #fffca2 Neon Orange #ffefc4 Red #fa8d54 Techno Blue #9aeaf1 Lime Green

#bafcc2 Purple #ffc8fa Berry #fbc6d2 Magenta #ffcdc7 Pink #ffe6cd







Neon Sharpie fluorescence

The Neon Sharpies came out with some great colours, but only the Neon Blue print remained strongly fluorescent under UV light (see image below).

Failure of Metallic Sharpies

The Metallic Sharpies failed to produce the expected metallic look under normal operation. It seemed like the metal particles were resistant to being extruded from my 0.4 mm nozzle. The metallic colour could be forced to come out by loading the printer with heavily-coloured filament (the filament was pulled through the Sharpie by hand to leave a thick coating on it), but the printed result was patchy and unreliable, and the nozzle became loaded with metallic particles that took nearly 7 cold-pulls to clean out (although the nozzle never jammed).

Inconsistent colouring from Metallic Sharpie. Printing with heavily-coloured filament did mean that some metallic particles made it into the print, but the result was not attractive.

Debris left in the nozzle from Metallic Sharpie. This is what remained after cold-pulling 5 times. The nozzle never jammed, though.

Considerations