Thanks to 3D printers, makers have the ability to bring any number of objects into existence, from missing hardware parts, to toys, to household items. But while the design freedom and capabilities of 3D printing may make it seem like you can make just about anything from the comfort of your home, it is important to understand what materials you are working with, especially if you are printing objects that will come into contact with food.
PLA (Polylactic acid) is a bioplastic material and is one of the most common 3D printing filaments available today. The plastic is derived from plants and is popular for its easy processing. Some of PLA filament’s benefits include that it prints at a lower temperature than many 3D printing materials, such as ABS, and it does not require a heated print bed. Because the material is made from natural materials, like corn starch and sugarcane, it is biodegradable and many assume it is food-safe. This can be true, but not in all cases. In this article, we answer the question “is PLA food-safe”, looking at what influences the material’s food safety and when to avoid food contact.
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What are the food-safe risks of PLA?
As a thermoplastic material, PLA is generally safe for food contact. In fact, a study from 1995 that put PLA material through several tests to determine how it breaks down found that it was “Generally Recognized As Safe (GRAS)” for food contact. When it comes to 3D printing, however, there are other factors that can affect whether the material is safe to use in contact with food.
In its purest form, PLA is food safe. However, if you are 3D printing with colored PLA filament, you should know that the additives used to dye the material may not be food safe. If you are 3D printing an object that will come into contact with food, like a mold or cookie cutter, it is safest to use natural (undyed) PLA filament. You can also consult the material information and safety data sheet for a particular filament brand to determine whether it contains any non-food-grade additives.
Another element that can affect PLA’s food safety is the 3D printing process itself. In many cases, the metal hotend of the 3D printer is made from a non-food-grade material. That metal is continually coming into contact with the filament as it is extruded, which can lead to potentially dangerous contaminating traces in your 3D printed part. Brass nozzles, for instance, can contain lead and potentially leach toxic particles into 3D prints. If you are concerned about whether your hotend will affect the safety of your 3D print, you can always opt to use a stainless steel nozzle, which is considered food-safe.
Something else to be aware of is the fact that bacteria and germs can get stuck in and grow in 3D printed parts. While they may look solid, FDM 3D printed parts have tiny pores in them that can trap moisture and provide a breeding ground for bacteria. If you do use a fresh 3D printed part to serve a snack, the pores can trap tiny particles of food, which can lead to potentially harmful bacteria growth. In terms of cleaning, it is difficult if not impossible to ensure that a PLA part has been properly sanitized for food contact once it has already come into contact with food. (The material is not very resistant to high temperatures and cannot be boiled or put in the dishwasher). This means it is safer to use a PLA utensil or plate once and then dispose of it.
Finally, it is worth mentioning that your 3D printer should be thoroughly cleaned if you are printing objects for use with food. If you have previously 3D printed non-food-safe filaments such as ABS, there may be traces of the material in the 3D printer that can contaminate a PLA print and make it hazardous. This includes the print bed as well as internal 3D printer components, like extruders and hotends. Ideally, you would use a dedicated 3D printer to print food-safe PLA parts.
Recommended reading: PLA Recycling: Can PLA 3D Printer Filament be Recycled?
Food-safe coatings for PLA
When 3D printing items that need to be food-safe, it is a good idea to err on the side of caution. One way to ensure that your PLA printed component is safe to use as kitchenware is to apply a food-safe coating or sealant. Epoxy resins are a common coating for 3D prints that will seal the surface. However, it is important that you find an epoxy resin that has been FDA certified as food-safe. You should also note that in liquid form epoxy resins contain toxic materials and must be handled with care (i.e. with gloves and mask). They are only safe when properly cured and hardened.
Another option is to use silicone as a food-safe coating. Silicone will seal the pores in the 3D print and result in a watertight surface finish. It is also less hazardous to use than epoxy resins. If you are aiming to make food-safe products that can be used safely over prolonged use, it is possible to 3D print a mold and cast it with food-grade silicone. There are also many examples of people 3D printing masters to make food-safe silicone molds. This is a great option if you want to make custom ice cubes, candies, or chocolates.
One disclaimer: a food-safe coating might wear down and degrade over time, so you should be wary of using your 3D printed kitchenware or food containers over the long-term. You should also read the fine print on the coating you are using: some are dishwasher safe and others are not and some are not suitable for use with hot foods or liquids.
Recommended reading: PLA vs ABS: Which filament should one use?
Ultimately, as a pure material PLA is generally considered food-safe; there are no toxic chemicals in the polymer itself. That being said, dyes or additives found in spools of PLA filament may not be food-safe. Other factors, like the 3D printer hotend material can also influence if a printed PLA part is safe to be used with food. Porosity in 3D printed objects can also lead to bacterial growth that can contaminate food.
It is therefore generally safest to apply a food-safe coating to 3D printed kitchenware to avoid any potential health hazards or to use PLA prints as single use items. Other filaments, such as PETG, may also be considered safe for printing food containers. Ceramics are another category of food-safe material if treated properly.