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Is Flexible 3D Printer Filament Food Safe?

The technology for 3D printers has come a long way since the original patent expired. Modern 3D-printed objects can be made with a variety of physical properties, including impressive flexibility. Flexible 3D filament has many applications, including phone cases, built-in vibration dampers, and protective sleeves applied to hard metal objects. But is it food safe?

Flexible 3D printing filament and filament products are not generally food-safe. This is due to the chemical composition of flexible filament and 3D printing filament in general, heavy metal contamination from the printer nozzle, bacterial contamination, and the difficulty in cleaning most 3D-printed objects.

This article will explore why flexible 3D printing filament is not generally food safe and discuss other food-safe uses of flexible filament.

What Is “Food Safe”?

According to the United States Food and Drug Administration, “food safe” means “a food-grade material is also suitable for its intended use and will not create a food-safety hazard.” 

That is legalese for “any material that probably will not make people sick if they eat food in physical contact with said material.” That is a reasonably nebulous definition typical of the era of corporate “self-regulation.”

Even under the relatively loose definition of the United States Federal Government, flexible 3D printer filament is not generally food safe. Here is why.

Chemical Composition

chemist working on formula

Plastic is not generally viewed as safe for human consumption, and flexible 3D printing filament comprises several kinds of plastic. The most common base materials of the 3D printing filament, flexible or not, are the plastics ABS and PLA

ABS plastic releases toxic fumes when heated, and PLA plastic provides a decent growth medium for bacteria. 

Chemicals added to plastics to increase flexibility are also not generally conducive to human health.

Heavy Metal Contamination

The metals used to make commercially available 3D printing nozzles can have dangerous side effects. Commercially available 3D printers usually work by melting several types of plastic and depositing the molten plastic on a hard surface. 

The nozzles typically have to be made of metal to withstand higher than average temperatures. The most common material is brass. Brass, an alloy of between 60% to 70% copper and 30% to 40% zinc, is a low-cost metal with a comparably high melting point around 900℃ (1,652 °F). 

While both are essential for the healthy function of the human body, higher than normal levels of copper and zinc are not healthy. 

All that said, the most significant problem with the brass nozzles used by 3D printers is the other metals included in the specific alloys – specifically, lead. Lead is used as a flux in the production of many commercially used metals due to its relatively low melting point. 

Humanity has known about the adverse health effects of lead for thousands of years. Still, we continue to use it for numerous applications because it is common and easier to work. To preserve your health, you should not eat with or from any object made using lead.

Bacterial Contamination

3D-printed objects may look smooth and solid to the human eye, but they are not. On a microscopic scale, the surface of 3D printed objects has crisscrossed microscopic fissures and cracks. These imperfections make excellent habitats for potentially dangerous bacteria and other microorganisms. 

According to a paper published in March 2021 in the journal Frontiers in Microbiology, surface imperfections on 3D-printed objects can house a “bacterial film.” A bacterial film is a colony of bacteria and other microorganisms that colonize any surface they can. You likely have biofilms living on your teeth. 

The problem is that these microscopic communities living on/in 3D-printed parts can include species that are infectious or produce chemicals that are toxic to humans. The writers of the aforementioned paper found several species of E. coli and staphylococcus bacteria present on sample 3D-printed parts. 

Several of said parts were “medical-grade,” intended for implantation in the human body.

Bacterial films can be destroyed by hot water above 130℃ (266 °F)and conventional antiseptic chemicals. Unfortunately, 3D-printed objects cannot generally be cleaned with these methods.

Cleaning Difficulties

At present, commercially available 3D printers use several different varieties of thermoplastic. Thermoplastics are polymer-based materials that become pliable or moldable when their temperatures are elevated and solidify when they return to room temperature. 

PLA plastic becomes pliable around 130℃ (266 °F) and melts between 170℃ (338 °F) and 180℃ (356 °F). That is also in the same range as the water temperatures used by commercially available dishwashers. ABS plastic melts at around 230℃ (446 °F), but as mentioned above, it releases toxic chemicals when heated. 

Products made with the most commercially available 3D printers and PLA-based filament is likely to melt or deform when exposed to hot water and therefore, cannot be cleaned with residential dishwashers. 

If you wish to clean it, you have to use other methods such as antiseptic chemicals. The problem here is that PLA, ABS, and most other base compounds used in flexible 3D filament are likely to react or dissolve on contact with traditional antiseptics like alcohol or acetone.

3D printer filaments that melt at temperatures above 300℃ (572 °F) are available, and theoretically, they could be dishwasher-safe. But most commercially available 3D printers are not designed to work at that temperature…

Food-Safe Uses

For the reasons previously described in this article, objects printed with either flexible or standard filament are not generally “food safe” but can be used in food-safe applications. 

One everyday industrial use for 3D printing is the production of molds used to produce finished products. Private owners of commercially available 3D printers can do this, although the design process in computer-aided design software required is a little more labor-intensive. 

Food-safe thermosetting resins, which can be dishwasher safe, are available online. Flexible 3D filament can make an ideal material for molding products made of such materials.

PLA plastic and nylon-based 3D printing filaments do not contain or release toxic chemicals. PLA, which is generally made from corn, does start to deform at a comparably low temperature of 60℃ (140 °F) and is sensitive to some antiseptic chemicals. Nylon-base filaments are more challenging to work with, though several are available that are approved as “food safe” by the US FDA.

To reduce the risk of heavy metal contamination, a potentially lead-contaminated brass nozzle can be substituted with one made of steel. These are more expensive and less common on the market.

Several websites dedicated to 3D printing have guides on post-production processes to make 3D printed parts food safe. These usually involve coating 3D printed objects with food-safe resins.

But if you cannot do any of those steps but still want to use a flexible 3D-printed utensil to handle food, at least try to keep contact between the utensil and your food to a minimum. 3D-printed items are inexpensive compared to traditional small production volume parts, with printing filament, costing on average 7.5 cents per meter. As a result, using a 3D printed eating utensil won’t cost you much if you don’t do it too often. PLA is also fully biodegradable.

Conclusion

In summation, flexible 3D printer filament and objects printed with it are not generally food safe. Flexible filaments can be used in food-safe applications. 3D printing will be one of the most critical technologies of the remainder of the 21st century. 

However, at present, you should not use anything 3D printed to handle your food, unless you’re willing to take additional steps in production.