Are 3d Printed Products Food Safe?
3D printing unlocked an entire world of possibilities when it comes to designing new components and complex tools that otherwise would be too expensive to make. The nature of this technology has also pushed the boundaries in the food industry because there are so many areas that can benefit from reliable but cheaply manufactured goods.
However, for anything made by a 3D printer to come into contact with food, we need to make sure there are no residual toxic substances or any compounds that provide bacteria with breeding grounds present. This means understanding and following food safety regulations and guidelines. Fortunately, this is possible even for 3D printing hobbyists because certain thermoplastics and materials used by printers are approved in the food industry. But there’s much more to it than knowing what food-safe material to use. Understanding what food-safe means can be challenging and the correct workflow is often confusing.
With that in mind, you’re going to be introduced to what food safety is all about and learn how to print food-safe prints using anything from the common FDM 3D printers to resin printers.
Introduction to Food Safety
First, there are three key terms you need to familiarize yourself with: food contact surface, food-grade, and food safe.
Food contact surfaces refer to all safe surfaces that come into direct contact with food. Therefore, a food contact surface has to be made out of non-toxic materials. In addition, it has to be resilient to the environment as well as the chemical compounds used to clean it. Food that comes into contact with such a surface is safe to eat.
Next, we have food-grade materials. These materials are rated as safe to come into contact with food or are considered safe for human consumption.
As for food-safe, the term refers to materials that won’t contaminate food and cause a food safety hazard.
Food safety is determined based on how different materials interact with each other during prolonged contact. In this case, we’re interested in how 3D printed products interact with food. Fortunately, various governmental institutions perform a series of tests to determine whether a substance or object is safe for human consumption. That’s why food-safe products have a label that specifies whether they’re approved by the FDA. On a side note, labels that say “compliant with” aren’t the same as those that indicate approval from an official institution.
That being said, there are a series of requirements that have to be fulfilled for the FDA or the EU to consider a product food safe:
- Durable, resistant to corrosion, and non-absorbent.
- Safe under intended use.
- Doesn’t impart any harmful substances, smells, flavors, or colors.
- Won’t degrade when washed.
- Easy to clean surface that is resistant to scratching, deforming, and any form of decomposition.
- Available for inspection.
To create a legally approved food-safe product, the 3D print has to go through the FDA’s or the EU’s approval process. However, when it comes to private use or consumption, you might not be interested in formal approvals. After all, you won’t submit a bunch of documentation and wait for months before you can use your new 3D printed teacups. So, let’s explore the possible dangers involving products that come into contact with food.
This is the biggest risk when it comes to anything that comes in contact with your food. Bacteria can give you a serious case of food poisoning or worse.
If your 3D prints have even micro-fractures, bacteria can enter them and multiply because cleaning agents can’t get to them. So, if you’re printing anything that you plan to reuse around your kitchen, you really need to make sure that your 3D printer is capable of creating a perfect model that won’t become a breeding ground for bacteria.
Furthermore, you can reduce the risks by sealing the print with a food-safe sealant. Sealants like epoxy or polyurethane (for PLA) are safe to use and they will cover all the tiny cracks and crevices where bacteria can hide.
On the other hand, if you intend to print disposable items, there’s no need to worry about bacteria.
Certain printing materials aren’t food safe because they contain toxic compounds. ABS is one of these materials and it can easily contaminate your food with certain chemicals that are bad for your health.
On the opposite side, we have PLA that is a food-safe organic compound. But, PLA isn’t the only type of filament you can use. Various PETG filaments are rated as safe, and other materials as well. To find out if a filament is food safe, all you need to do is check its information sheet that contains all the chemical properties. There you will find the approvals from the FDA.
The filament is just one piece of the puzzle. Many FDM printers release ultrafine particles during the printing process, especially when using ABS. These particles are toxic for human consumption and they tend to settle on whatever your printing. In addition, these particles are so fine that you might be inhaling them while the printer is running. Short exposure to them isn’t a big problem, but long-term exposure can cause serious health issues.
To prevent damaging your health, you should be working in a ventilated room. And don’t keep your food anywhere near the printer. Otherwise, properly cleaning your prints will get rid of these ultrafine particles. Anything that remains is in a negligible quantity.
Prints can warp over time, especially if you wash them in really hot water or in a dishwasher. Over time the plastic changes its shape and tiny cracks can appear. This issue leads us back to the bacteria problem because any deformation can become a gateway to those microscopic pests. PLA is particularly sensitive to heat and mechanical stresses because of its low melting point and brittle nature.
The best thing to do to ensure your 3D print stays food safe is avoiding dishwasher and hot water. The ideal way to clean 3D printed objects is with lukewarm water and antibacterial soap or detergent.
If you have an FDM printer with brass extruders, you need to replace them. Brass often contains lead, which can lead to severe health issues. Check your printer and see what the nozzle is made of. If it’s steel or aluminum, it’s safe to use. Otherwise, replace it or you’ll end up with contaminated food.
That being said, the safest option is stainless steel. As you probably know, all restaurants use stainless steel utensils and pots because they’re food safe. The same goes for the extruder. If you plan to create prints that will come often in contact with food or drinks, you should be working with stainless steel as much as possible.
Food safety depends a lot on how you’re using your 3D printed products. Some of them don’t even have to be properly rated as food safe because they will never come into contact with you. For example, as long as your knives don’t leave any toxic compounds or bacteria on whatever you’re cutting, they are safe to use because you don’t stick knives in your mouth. Limited exposure is highly unlikely to cause harm even when non-food grade filament is used.
On the other hand, if you’re making a food container, a spoon, or a tea mug, those items come into prolonged contact with you and your food. So you really want to make sure they’re safe to use. However, printing a completely food-safe product is difficult, especially if you’re a hobbyist.
The best thing you can do is choose the correct material for the intended use. For example, using PLA filament to make a coffee mug is a terrible idea, despite it being technically food safe. PLA will soften up, warp, possibly even melt, and you’re going to ingest some of the chemicals inside it. This is a case of not using PLA the way it’s intended and suddenly it goes from being a safe material to a risky one. However, as mentioned, there are plenty of options out there that aren’t PLA or ABS. With the right printer you can even print using ceramic materials, and those are ideal for coffee mugs.
FDM Food Safe Printing
FDM 3D printers are the most commonly used ones, especially at a hobby level. This type of printer melts and extrudes thermoplastic and deposits the material layer after layer in a certain pattern.
Because of the way FDM printers operate, there’s a chance of having small, barely noticeable gaps between the layers where bacteria can build up. To solve this problem, you should check the layer height settings and choose the lowest value you can when printing food-safe products.
That being said, the biggest concern with FDM printers is bacteria. Obtaining a perfectly smooth surface can be challenging, but certain post-processing methods can help. One of those methods involves the use of chemical agents, like acetone. This chemical is excellent for smoothing the surface of the print until it shines perfectly, thus removes any invisible crevices where bacteria can hide. Once this step of the process is done, you can coat the model with a food-safe additive for additional protection.
FDM Food Safe Materials
As mentioned earlier, to obtain a food-safe product we need to print using food-safe filament. Among the safest materials, you’ll find PLA, PET, PETG, copolyester, PP, HIPS, and even certain ABS filament brands that are rated as food safe. Whatever you purchase, make sure it’s correctly rated. Don’t make assumptions when it comes to someone’s health.
With that in mind, the type of material also depends on its use and how you intend to wash it. As mentioned, PLA melts easily and warps quickly, so it’s a bad choice if you plan to use hot liquids or a dishwasher. This is where co-polyester and PEI come in. Whatever you use, it should be rated as food safe.
Finally, you should perform regular maintenance to keep your FDM printer clean from fine dust and ultrafine particles. Limit the chance of contaminating your prints with anything that doesn’t belong in their composition.
SLS Food Safe Printing
SLS printers are becoming more and more common and they make a good candidate for printing food-safe products. This type of printer relies on a laser beam to fuse polymer material and thus form a pattern that eventually becomes a usable product. The material of choice is usually nylon.
Some SLS materials are rated as food safe, however, prints often end up with porous sections where the nylon wasn’t properly fused. This is a potential magnet for mold and bacteria due to the moisture that fails to escape those pores. Therefore, to use SLS prints in the kitchen, you should coat them with special food-safe additives to create a protective layer.
Food safety is a serious matter that shouldn’t be taken lightly. When it comes to 3D printed products, we can’t think in black and white terms. There are multiple considerations to make before printing something that will come in contact with food. Anything from the choice of material to the type of printer and the purpose of the product will determine how safe something is. Achieving 100% food safety is extremely difficult, but that shouldn’t stop you from trying. If you take every precaution and make the right decisions, it is highly unlikely to endanger anyone’s health.