All-natural 3D printers use salt and wood

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The fast-growing field of 3D printing has been gaining a lot of attention. But one intriguing project coming out of the University of California Berkeley aims to use natural resources like salt and wood to reduce 3D printing costs.

Professor Ronald Rael, part of Berkeley's architecture department, has been spearheading the initiative over the past few years, and he says it is now getting closer to commercialization.


The studio project began as a way to look into making architecture in the Bay Area using local materials, Rael explained. But it's taken on life from there.

"I wanted to 3D print, but I found the materials were very expensive. So I wondered if it was possible to print with less expensive materials—and if we could invent our own materials that would be less expensive," Rael said. [Read also: "3D Print Your Own Invisibility Cloak at Home."]

He began with ceramic powder, and had some success with that process. From there, two years ago, he moved on to cement, the material he and his team have worked on the longest. The implications for cement-based architecture were huge: With Rael's fiber-reinforced cement polymer, 3D-printed cement doesn't require a framework like conventional cement. "This means we can make complex shapes without framework, which is 60 percent of the cost of construction," Rael said. Last year at Maker Faire, he brought an 11-foot long 3D-printed bench called the Seat Slug.

In the past year, Rael began expanding the printing materials to include salt and wood. The wood is sawdust from maple, pine and pecan trees used in the lumber industry. The 3D-printing process used by Rael's team is different than the "extrusion" process used by competing approaches.

The UC Berkeley team uses powder forms of raw materials, and mixes the powder with a customized solidifying agent that responds to water. After layering the powder using printers from 3DSystems, he says, they'll spray a fine mist of water over the powder to solidify and strengthen the material. The material is waterproof and very strong, according to Rael. The cement process is already patented (to U.C. Berkeley).

While in the near term Rael uses the process to build models and components in class, the practical applications are boundless. "We are looking at how these materials can be used to make buildings and building compounds," he said.

The group aims to create a startup later this year to bring this technique of 3D printing to market. The goal, Rael said, "is to make large-scale 3D printed objects using commercially available 3D printers. We can make from anything in powdered form, from fly ash — a waste material from the coal burning process — to bone."

Salt is extremely inexpensive, and can be harvested from the San Francisco Bay through evaporation processes.  Whereas the standard powder for a 3D system could cost $3,000 for 100 pounds, salt costs just $16.

Being able to 3D print entire buildings will raise new intellectual property issues, Rael said.

"Does this mean people can download your building and print it?" he said. "This is going to require some IP protection for designs, so if you design architecture in the computer, you're protected, just as music and movies are."