Some of the most practical and simple designs made for 3D printing are those made to contain some sort of food or beverage – mugs, plates, bowls, and similar objects. However, have you given some thought to how safe these 3D printing filaments are with respect to coming in contact with your food? In this article, we discuss the potential dangers of using 3D printed food containers, which filament you can use, and the best practices for making food-safe 3D prints.
What are the dangers of using 3D printed objects as food containers?
1. Some filament materials release toxic compounds
ABS may be one of the most popular 3D printing materials because of its thermal stability and ease of use, but it also releases a suite of toxic compounds which may contaminate food it comes into contact with. Many filaments also contain additives, which may provide color or increase in strength, that can also leach into your food or drink.
Before deciding to use your prints to contain food, we recommend checking with the manufacturer if the material is indeed food safe. If in doubt, you may check the database of food safe materials from the FDA.
2. 3D prints are prone to bacteria buildup
Unlike the injection molding technology used for commercial-scale production of food and drink containers, 3D printing creates objects layer by layer. This method creates striations or grooves along layer boundaries which carry over to the final product. Thus, unlike injection molded plastics, 3D prints do not have a smooth surface.
This is particularly problematic if we’re talking about using them as food containers. Leftover food material can easily get stuck into these grooves and removing them by traditional cleaning methods is practically impossible. This makes 3D prints prone to bacterial growth when used as food containers.
Making the matter worse is the fact that not all filament materials are dishwasher safe. For instance, PLA has a glass transition temperature of only around 60 °C. This is well within the temperatures that many dishwashers operate on, as they can usually reach temperatures of up to 75 °C. This means that your PLA print will soften and deform inside a dishwasher. Worse than having a ruined PLA print, this can also end up damaging the dishwasher itself.
3. Some brass nozzles release lead during the printing process
Most 3D printers use a standard brass nozzle for the hot end, and this introduces a few more problems in the context of making food safe products. Some brass products may contain lead, and this can ultimately contaminate the product that is extruded from a brass nozzle. Nobody is really sure how much of the lead in the brass can be transferred to the final print, but we’re pretty sure you would not want to risk lead poisoning to find out.
Another issue lies in the fact that your hot end nozzle has probably been used to print with other filaments. Whether that’s ABS, PETG, or HIPS, there is likely a chance of carry over of residual compounds and chemicals from one print to the next. This means that your food safe PLA print may be contaminated with the harmful chemicals released from the ABS print you made last week.
As you can see, problems of food safety for 3D printed objects extend beyond whether the filament is food safe or not. The nature of the technology and the process itself does not lend well to making food safe products. However, there are some way to make it work, if that’s really the direction that you are headed.
How can I make my prints food safe?
1. Make sure your filament is food safe
PLA, being manufactured from plant material such as corn, is probably the most popular food safe filament material. The PLA filaments from MakerBot are even colored with FDA-approved food safe dyes, making them comprehensively food safe. There are a few other PLA products, such as those sold by All Professional 3D and Kitchen & Deco, that have been FDA-approved for use with food applications. However, keep in mind that PLA starts to deform at around 60 °C, so it’s probably not a good idea to put hot drinks or hot food in your PLA-made container.
Natural grade nylon is another popular material for 3D printing food safe products. Nylon has a little less tendency to deform at high temperature and does not release harmful compounds when it decomposes. Take note that natural grade or food grade nylon is distinctly different to black nylon or nylon with other additives. To eliminate doubt, make sure that the particular nylon filament you are using is FDA-approved. A good example is the Taulman Nylon 680 filament.
How else can you check if your filament is food safe? Each filament should ideally come with a material safety data sheet (MSDS) which contains information on the possible chemical breakdown products of the material, and whether or not it has been declared food safe.
2. Do post-processing to get a smooth finish in your prints
Aside from the filament material, the manner in which 3D prints are made also poses problems in printing food safe products. The small grooves that are naturally left in any 3D print provides a prime breeding spot for bacteria. This can be solved by applying a layer of coating to the print, given that the coating has been FDA-approved for food applications.
The coating you use should ideally be stable in high temperatures and be resistant to typical food compounds such as acids and oils. There are several epoxy resin products available in the market that satisfy these requirements. Application of this coating not only will make your product safer for food applications, but the print will also end up having a shiny gloss that will improve its aesthetics.
3. Limit the contact time of the print with food
Making bowls, plates, and mugs – objects that will be in contact with food for a long time – is probably an ill-advised idea, no matter what filament or coating you use. A more prudent idea would be to make items that will only be in contact with the food for a short period. A few good examples are knives, cutlery, spatulas, cookie cutters, and measuring cups. Less contact time should mean less chances of leaching of harmful compounds in the filament material.
Do not, under any circumstance, use your 3D printed product to handle raw food material such as raw eggs, meat, or fish. Given the propensity of 3D prints to harbor bacterial growth, exposure to raw food will only serve to make the problems a few magnitudes worse. Using your 3D printed knife to cut bread or cheese is fine, but please don’t use it to slice raw fish.
4. Use a pure steel nozzle
Since we already know that using a brass nozzle can result in the leaching of lead to your print, we recommend using a stainless steel nozzle when making prints meant for food applications. If you’re really serious about making food safe prints, then it would also be worthwhile to avoid cross contamination and use a separate nozzle (or even a separate 3D printer) when cranking out food containers. This sounds like taking precautionary measures to a different level, but we would not want to take food safety lightly.
As you can see, making food safe 3D prints is a lot more complicated than how it appears on the surface. Even though there are dozens of food safe filament products available in the market today, the issue of bacterial buildup on the final print poses another problem. The practicality of 3D printing food containers is also quite questionable, given that some materials cannot handle high temperatures without deforming or releasing toxic compounds. You must also keep in mind that the oils and the acids in food can react with the material in your print, producing complex chemical compounds that you probably would not want inside your body.
Eating food off of a 3D printed bowl is probably fine for one or two instances. Any chemical compound that the food leaches from the plastic material will be in very small amounts. However, long-term and repeated ingestion of said compounds will likely lead to accumulation in the human body. We are not doctors, and we do not know how the body will react to this accumulation, but it does sound like a bad enough idea for us to suggest avoiding even that remote possibility.
Bowls and mugs are very easy projects for 3D printing, but would it be wise to use them to hold food or drinks? We think that the risks in using 3D printed products for food applications far outweigh the benefits, making it an impractical venture. If you’re really interested in making a custom mug or plate, we suggest using a professional 3D printing service that will fabricate your design using genuine food safe materials, such as ceramic.