colored 3d printer filament

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A graph is shown of the percentage reflection of visible light as a function of wavelength. Four lines are traced on the graph, which all approximate the same shape. In the top left, two purple shapes are shown, which the spectral chart describes.

Paint Mixing Theory For Custom Filament Colors

April 28, 2025 by 11 Comments

Recycling 3D filament is a great idea in theory, and we come across homemade filament extruders with some regularity, but they do have some major downsides when it comes to colored filaments. If you try to recycle printer waste of too many different colors, you’ll probably be left with a nondescript gray or brown filament. Researchers at Western University, however, have taken advantage of this pigment mixing to create colors not found in any commercial filament (open access paper).

They started by preparing samples of 3D printed waste in eight different colors and characterizing their spectral reflectance properties with a visible-light spectrometer. They fed this information into their SpecOptiBlend program (open source, available here), which optimizes the match between a blend of filaments and a target color. The program relies on the Kubelka-Munk theory for subtractive color mixing, which is usually used to calculate the effect of mixing paints, and minimizes the difference which the human eye perceives between two colors. Once the software calculated the optimal blend, the researchers mixed the correct blend of waste plastics and extruded it as a filament which generally had a remarkably close resemblance to the target color.

In its current form, this process probably won’t be coming to consumer 3D printers anytime soon. To mix differently-colored filaments correctly, the software needs accurate measurements of their optical properties first, which requires a spectrometer. To get around this, the researchers recommend that filament manufacturers freely publish the properties of their filaments, allowing consumers to mix their filaments into any color they desire.

This reminds us of another technique that treats filaments like paint to achieve remarkable color effects. We’ve also seen a number of filament extruders before, if you’d like to try replicating this.

Coloring 3D Prints With Sharpies

May 8, 2014 by 64 Comments

Printing objects in full color easily is one of the paramount goals of the ‘squirting plastic’ 3D printer scene, and so far all experiments have relied on multiple colors of filament, and sometimes multiple extruders. This, of course, requires a stock of different colored filaments, but [Mathew Beebe] has a different idea: why not dye a natural colored filament just before it’s fed into a printer? Following his intuition, [Mathew] is doing some experiments with the common Sharpie marker, and the resulting prints look much better than you would expect.

The basic procedure or this technique is to drill a hole in the butt end of the Sharpie, pull out the felt in the tip, and feed a length of filament through the marker before it goes into the extruder. The filament is dyed with the Sharpie ink, and the resulting print retains the color of the marker.

Despite the simplicity of the technique, the results are astonishing. An off-white ‘natural’ filament is easily transformed into any one of the colors found in Sharpies.

Besides the common Sharpie, there’s a slightly more interesting application  of this technique of coloring 3D printer filament; as anyone who has ever been in a dorm room with a blacklight knows, you can use the dye inside a common highlighter to make some wicked cool UV-sensitive liquor bottles. Whether the ‘Sharpie technique’ works with highlighters or other markers is as yet unknown, but it does deserve at least a little experimentation.

Video below.

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