The Changing Color of 3D Printing
Jeffrey Heimgartner posted on February 07, 2018 |
MIT researchers change the color of 3D-printed objects with ultraviolet ink.

The concept of 3D printing has been around since the 1980s and has developed into an ever-evolving technology that is used across industries by businesses small and large, as well as the public sector. From their humble beginnings when they were used to print small, basic pieces, 3D printers are now used for complex projects of various sizes, materials and colors.

One common thread in this evolution has been the “finality” of a print. Any required changes meant cleaning off your build plate and printing again. Researchers at MIT's Computer Science and Artificial Intelligence Laboratory (CSAIL) have taken the first steps toward changing that process with the release of their paper on ColorFab, a method for repeatedly changing the colors of 3D-printed objects using ultraviolet light (UV).

“This is the first 3D-printable photochromic system that has a complete printing and recoloring process that’s relatively easy for users,” said Parinya Punpongsanon, postdoctoral associate and paper coauthor. “It's a big step for 3D printing to be able to dynamically update the printed object after fabrication in a cost-effective manner.”

The days of disappearing ink or magical markers that turn purple and green now seem long a thing of the past. The MIT team developed its own 3D-printable ink that changes color when exposed to UV light.

According to the press release, the team’s custom ink is made of a base dye, a photo-initiator to harden the base dye during printing process, and light-adaptable dyes that bring out the color in the base dye. UV light is then used to change the pixels on an object from transparent to colored—to activate the desired colors—and a regular office projector turns them from colored to transparent—to deactivate colors. Too see a video of the process, click here.

To develop their method, the team first created a workflow using the ColorFab interface. This involved uploading a 3D model, picking color patterns and printing. Then, the researchers tested ColorFab for its recoloring time, precision, and how quickly the color decayed. The results: a full recoloring in 23 minutes. The researchers believe that this process time can be reduced through improvements in lighting and the light-adaptable dye used in the ink.

As for color, as with most new things, there is always room for improvement. The team found the colors to be a bit grainy, but plan to change that by activating colors that are closer together on an object. They believe, for instance, that activating blue and red might show purple, while activating red and green would likely show yellow.

What does the team’s discovery mean? Well, what if the newest and coolest things could be obtained with just a little UV instead of an entirely new purchase? While the project is focused on plastics and other common 3D-printing material, the goal is for people to be able to instantly change the colors of things such as their clothes or accessories.

“Largely speaking, people are consuming a lot more now than 20 years ago, and they're creating a lot of waste," said Stefanie Mueller, MIT professor and paper co-author. “By changing an object's color, you don't have to create a whole new object every time.”

MIT Professor Stefanie Mueller in her lab. (Image courtesy of MIT.)
MIT Professor Stefanie Mueller in her lab. (Image courtesy of MIT.)

Considering that the average American throws away approximately 82 pounds of used clothing per person a year, a little light could have a big impact on reducing waste. The MIT team’s work also could have an up-front impact on future waste. Retail stores with color-changing 3D-printing technology could customize products in real-time, allowing consumers to try before they buy, and make a color match.

Interested in more 3D printing? Check out The Real-World Cost of a 3D-Printed Prototype.

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