If you want to 3D print utensils used for food and beverages, you need to make sure it is non-toxic. That's it.

Low-cost 3D printers such as Creality Ender-3 enable ordinary people to use additive manufacturing. But food is one thing that people enjoy more than making custom plastic products in the comfort of their homes.

It is natural that these two pursuits intersect in the form of 3D printed vessels. Unfortunately, these two are used together with vinegar and bleach. In other words, 3D printed food containers are toxic enough to make you die slowly.

Read on to learn why this happens and what steps you can take to solve the problem.

Generally speaking, plastics have become notorious for their long-term adverse effects on health and well-being. There are a lot of warnings about bisphenol A, phthalates, and other plastic-related endocrine disruptors.

But let us cover up the horror of plastic genital shrinkage in general, and limit the scope of this effort to the more pressing toxicological aspects of 3D printed plastics.

The following are the ways in which the 3D printing process makes plastic more unhealthy than others have blamed. The first is the special way in which FDM 3D printers tend to make plastic objects.

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Traditional injection-molded plastics are absolutely hermetic because objects are made by pressing the material into a mold under extremely high pressure. The surface finish of this plastic object is smooth, without any holes or cracks.

On the other hand, 3D printed objects are manufactured by stacking hundreds or even thousands of plastic layers, and the internal geometry of the part itself is hollowed out into many air pockets.

The high degree of porosity of 3D printed parts makes them a powerful breeding ground for deadly bacteria such as Salmonella and E. coli. It is well known that these pathogens cause chronic diseases and are incredibly resistant to most fungicides.

Therefore, food safety appliances need to have smooth, non-porous and easy-to-clean surfaces, which are inherent to 3D printing appliances.

The concept of particle migration is an important factor in food safety. Particles of hundreds of nanometers can be exchanged between solids and when interacting with liquids on a microscopic level.

This is the main mechanism by which toxic substances are transferred and leached onto 3D printed plastics and then into food eaten through such utensils.

Factors such as exposure time (long-term storage), friction (scraper), temperature (cookware), and the reactivity of the materials involved (acid/alkaline food) determine the degree of particle migration. This is why certain reactive foods must be stored in glass jars, but there is still no problem when they are eaten with metal utensils.

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On the business side of 3D printers, things have become very hot. Your 3D model is rendered as a physical part with molten filament extruded from the hot end assembly. Among them, the filament is in close contact with the thermal circuit breaker and the nozzle.

The former is usually made of stainless steel, so there is little risk of immersing toxic substances in the filament. However, the raw material nozzle is usually made of brass, which is known to immerse a small amount of lead in the filament.

From a health and safety point of view, this is absolutely impossible.

The brass extruder gears in most common 3D printers work by applying a lot of pressure and friction to the filament. In addition to brass nozzles, they can also dip lead into 3D printed plastic.

Most 3D printers also use a PTFE liner tube between the extruder and the hot end part. Although this material is food safe, the material used in 3D printers contains lubricating additives and may be toxic.

Other components used in 3D printers, such as build surfaces, filament rolls, and lubricants, are additional ways for harmful substances to be transferred to the printed part. It is undoubtedly a difficult task to make your 3D printer truly food-grade.

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Although PLA is touted as a biodegradable filament synthesized from sugars in corn or sugar cane, different brands introduce various additives to enhance the printability, durability, and other physical properties of printed parts. These additives themselves may be toxic, making the printed parts unsafe for food handling.

The US Food and Drug Administration (US FDA) issues food safety approvals for well-known filaments. This is a good starting point to find out which filaments can be used for printing appliances.

However, it is recommended to check and approve on a per filament basis. Although there are concerns surrounding the leaching of styrene into food from ABS printed parts, a large number of commercial ABS filaments have received FDA approval, and some PLA filaments are not due to the use of specific color pigments.

Just because a particular brand of ABS is certified as food safe, you cannot assume that the courtesy extends to ABS filaments from another brand. Different color iterations and additive blends also play an important role in FDA certification, so be sure to check the details.

Now that we are clearly aware of the dangers of using 3D printed tableware to make food, we will neglect to leave without providing some tips on how to 3D print food grade parts.

First, configuring a separate 3D printer for food-grade printing is the easiest way to ensure FDA compliance. This is an inconvenient requirement because toxic substances will linger in several printing cycles.

Here are some tips and tricks to improve the safety of 3D printed food.

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Learn how brass nozzles and extruder gears can potentially introduce lead into your 3D printed parts, and replacing them with stainless steel alternatives is the easiest way to make them food safe. Be sure to use food-safe stainless steel parts, because the variants of tool steel are not the same. In addition, stay away from stainless steel nozzles with additional non-stick coatings.

The layer line is an important factor leading to the porosity of FDM 3D printing and creates conditions conducive to the growth of bacteria. Fortunately, some filaments such as ABS, ASA, PETG and HIPS can be smoothed chemically.

This involves partially melting the layer lines through a steam smoothing process, which allows solvents such as acetone and ethyl acetate to react with the surface of the 3D printed part. The result is parts with smooth, sealed surfaces that are easy to clean and lack the surface area required to carry bacterial colonies.

For filaments that cannot be chemically smoothed, you may need to lower the layer height to make the 3D printing as smooth as possible. Further sanding the surfaces should make them smoother. Just make sure that the grinding equipment does not introduce toxic substances.

Although PLA is generally food safe (as long as the manufacturer does not use toxic additives or color pigments), 3D printed parts are not practical for long-term food handling. This material has one of the lowest heat distortion temperatures (HDT). This means that it cannot survive hot drinks or heated dishwasher cycles.

The chemical inertness of PETG filament makes it ideal for food processing, but like PLA, it also lacks the HDT needed to survive hot food and dishwashers. However, PETG can be smoothed chemically. However, ABS filaments can produce heat-resistant 3D printed parts, which can also be steam smoothed.

Exotic filaments such as PEI (Ultem brand) have been approved by the US FDA, but they cannot be printed on non-commercial 3D printers. At the same time, nylon and polypropylene filaments also meet FDA food safety standards.

It is still a good idea to check the filament packaging for FDA approval.

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It is not easy to adapt your printer to new materials. In most cases, entry-level FDM printers can't even print materials such as ABS out of the box. This makes dip coatings and sealants a viable alternative.

They have different food grade options such as polyurethane resin, epoxy resin and PTFE coating. The options are almost endless, so make sure you do your due diligence on FDA approval and compatibility with various filaments.

It is also worthwhile to check the temperature and wear resistance of these solutions in advance. You don't want to use low temperature coating for coffee cups.

The concept of food safety 3D printing is currently uncharted territory. Although the FDA has been conducting due diligence and approval on well-known filaments, it still cannot control the unknown variables and unpredictable use cases of printing temperature.

After long-term use, certified food safety products may be different. In addition, it is wiser to reduce food temperature, contact time, and generally avoid pairing 3D printed appliances with reactive foods.

It is wiser to proceed with caution.

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In his 15-year career, Nachiket has covered various technological beats from video games and PC hardware to smart phones and DIY. Some people say that his DIY article is an excuse to pass his 3D printer, custom keyboard and RC addiction as "business expenses" to his wife.

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