Researchers from the University of Toronto have done something amazing: they have transformed used cooking oil into a practical and inexpensive 3D printing resin. 

The resins typically used by today’s SLA & DLP 3D printers are photopolymer liquids, which react when exposed to UV light at certain frequencies. Resins are available in many forms, and can often be found mixed with other building materials such as ceramics or even metals. 

There are big challenges with today’s 3D printer resins, however. 

One is that they are usually priced very high. Some time ago we spoke with one of the few actual manufacturers of photopolymer resin (virtually all of what you see for sale is re-labeled product from these few manufacturers). We learned that resin can be manufactured at costs as low as US$10 per liter, some 20X less expensive than some sources charge for their marked-up resin. 

Some of that pricing is due to the monopoly effect, where the resin machine is designed to accept only resin from the manufacturer. But resin prices are still pretty high in other cases, too. 

Cooking Oil Resin

The University of Toronto breakthrough could change the pricing equation, however. 

They have managed to convert a quantity of leftover cooking oil from a local McDonald’s restaurant into usable 3D printer resin. They explain what happened:

“<The> team used a straightforward one-step chemical process in the lab, using about one litre of used cooking oil to make 420 millilitres of resin. The resin was then used to print a plastic butterfly that showed features down to 100 micrometres and was structurally and thermally stable, meaning it wouldn’t crumble or melt above room temperature.”

Recycling Cooking Oil

I’ve heard of cooking oil being recycled for different uses, including making diesel fuel, and I’ve personally encountered a vehicle powered by cooking oil, as seen here. This Zamboni (a device for recoating ice rinks) runs entirely on cooking oil collected from local restaurants. It’s a bit of an experience skating behind it as it rolls along the ice, because it smells very strongly of French fries. 

Here the UofT researchers have found a way to transform the oil into something quite practical. They have been able to 3D print objects using what appears to be a standard desktop resin 3D printer, and the prints seem to be of good quality. 

Cooking Oil 3D Printer Resin Benefits

There are three benefits to this approach. 

First, the resulting 3D prints are entirely biodegradable, and that’s because they are literally made of fat. Nature is already very capable of consuming leftover fat, so we will never see long-lived waste from these prints. 

Secondly, the oil is sourced at extremely low prices — many restaurants simply give it away because it is waste to them. The UofT researchers suggest that their process could produce usable 3D printer resin for as little as US$300 per tonne — or US$0.30 per liter. That’s a game changer, if the material is truly usable. 

Finally, most of today’s 3D printer resins are toxic. Some are extremely toxic and should not be touched or breathed, and in some cases can result in horrifying blisters that require hospital care, as one individual experienced. It’s quite likely the oil-based resin is not particularly toxic. 

However, I have some questions. 

Cooking Oil 3D Printer Resin Potential Problems

One is whether the prints could be food safe. In order to be food safe, everything in contact with the material before and during 3D printing must also be food safe. I’m not sure that’s the case with resin 3D printers, so the production of food safe prints may be challenging. 

The second issue could be the durability of the cooking oil prints. While they are definitely biodegradable, I’m wondering exactly how strong a fat-based 3D print could be. I’m also wondering about its temperature resistance. It may be that, like PLA, these 3D prints have a low glass transition temperature, which would negate their use in many scenarios. 

Nevertheless, this is a very interesting step that could be built upon to possibly offer commercial resins at better price levels and with better safety features. 

And I’m really wondering how these prints smell. 

Via University of Toronto (Hat tip to Benjamin)