Are 3D Prints Safe for Food Use?
Overview
Every once in a while when I'm online searching for something new the 3D print, I will come across a really cool looking cup or cookie cutter, or some other kind of food or drink related product. Early on in my 3D printing hobby, I often wondered if I printed these, if they'd actually be safe to eat from.
The short answer I've found is that while the most common home 3D printing material, PLA, is considered fairly safe to use in the home and is technically food safe in pure form; there are possibly additional chemical additives within the PLA filament for 3D printing. This gives the filament its color or other characteristics. Because of the risks of not knowing what these chemicals are, it's much safer to assume that nothing is food safe as soon as you print it. There are ways however, too do a little extra work that will allow you to use a 3D printed cup or other food related item.
Most Common 3D Filaments and Food Safety
It's very likely that 3D printers in the home will be using one of two materials as filament to print the 3D objects. While there are other types of printers out there, and some more "unusual" filaments that can be purchased, by far the most common two are plastics called PLA and ABS.
PLA Plastic:
I will start with PLA, the most commonly used filament for home 3D printers. I have a more detailed article about the material here if you'd like to find out more. What exactly is this material and is it safe to use?
PLA plastic stands for "Polylactic Acid". In short, PLA plastic is made out of plants! In it's pure form, PLA is actually considered a food safe material and it's biodegradable! This same type of plastic is used for eco-friendly plastic utensils, cups, and plates. Keep an eye out next time you're at the grocery store and you might notice them.
All of that said, PLA plastic filament for 3D printing is still not technically considered food safe. Not to mention, the heat-resistance is low and the material is brittle.
While this filament retains some of the great benefits of PLA, read on to find out why even this "safe" plastic may not be the best for coming in to contact with your food.
ABS Plastic:
ABS plastic staands for "Acrylonitrile Butadiene Styrene". Besides being very difficult to say, this plastic is a complete no-go for food safety in my mind. In fact, I don't recommended you use this material indoors without significant ventilation. The fumes from this melting plastic may be harmful over time.
ABS plastic is what you probably think of when it comes to plastics. It is not eco friendly because it's petrolium-based and it is not biodegradable. Once it's created, it stays around forever. It's great for making strong parts, but not for sustainability.
Based on the research I did for this article, there are no conclusive long-term studies of this plastic, it's fumes, and generally how safe it is. It's probably best to be cautious and not use untreated ABS for food-related projects.
If I use a "Safe" Plastic, Why isn't a 3D print food safe?
There are a few reasons that I've seen why you would not want to use something like a 3D printer to create items for use with food, even if you find a filament that is considered to be a food-safe material. There may be some sources out there that say you're fine but again, I prefer to err on the side of caution.
Additives
Reason number one is that most 3D printing filaments have additives. PLA, also known as Polylactic acid, in its basic form is generally regarded as food safe. In fact, it is the same type of plastic used in things like biodegradable drink cups.
The problem with using PLA filament however is that along the way, dyes and other materials are added to PLA to make it look nice for 3D printing. Since you can't be sure what those dyes and additives are, its you wouldn't want to eat from them. Not to mention even if you did find a 100% food safe PLA filament, your printer might be depositing small bits of metal or old filament that you wouldn't want to eat either. So overall, it's not a good idea.
Hygiene
Reason two for not using 3D printed models to eat off of is a simple issue of hygiene. Because of all the small cracks and crevices that are created for the process of 3D printing in layers, it's extremely hard to clean these items well. It's possible for bacteria to get stuck and grow within small cracks and again it's probably something you shouldn't be ingesting.
Unfortunately this is just a matter of fact when it comes to 3D printing at home. Since 3D printers print everything in layers, there are always areas for bacteria to get stuck and grow.
Contamination
It's extremely likely that the first project someone takes on with their 3D printer isn't a food-related item. What's more likely, is that someone has been using their printer for other projects before deciding to create something like a cup, bowl, or cookie cutter.
Because of this, most printers have some type of contamination from the other materials. Even if you find a filament that claims to be food safe, the other materials you printed with before most likely left particles behind along with burnt bits of old filament. While it's probably a minimal amount of contamination, it's still not going to be good for someone to eat off of it and only a little can be harmful, especially over time.
How to Make Prints More Food Safe
Don't worry though, all is not lost! There are possibilities for utilizing 3D prints in cases where food safety is a necessity. As always, make sure to do your own research, but these are some tips that I've come across over the years that I wanted to share for those who would like to attempt making prints food safe.
Warning: Keep in mind that these are not absolute guarantees that these items will be safe for food use, so please do additional research before attempting a project meant to come in contact with food or drink. These are just suggestions and not evaluated by any professional.
Upcycling
The first option, not to mention the simplest and probably the safest, is to simply find or design a print that "upcycles" an existing object that is already food safe. (MyMiniFactory.com has a great upcycling category for some examples). For example here is a great-looking tiki glass, however I would not want to drink directly from it, even if it was a rare water-tight print.
That said, it would be easy enough to put another vessel in there have it fit snugly. That way you can still use your fancy looking cup but be drinking from a food safe container. I know this seems like a bit of a cop-out for someone who wants to 3D print a drinking glass, but it is the easiest option and if you are able to do your own designs you can do some extra work to nearly completely conceal another container within the item you've made.
Finish with Food-Grade Material
The next option is to do some finishing work on the front and coat it in a food safe materials like food-grade silicone or polyurethane. This requires a bit more work and you are likely to lose some details in the print but if you do it right you can get yourself a food safe surface that is also smooth to make sure no bacteria gets stuck.
To do this, you will have to track down a food-safe polyurethane and coat your final print in it. Wait for it to dry and voila! A container that you can actually use! make sure to read the descriptions of your urethane clearly and only purchase something that is food-grade/safe for use.
Create a Mold for Casting
One final option for making great 3D printed items, is to simply cast a silicone mold of your final print. There are various methods depending on the model you are trying to do. I would recommend looking for videos on "two-part silicone molds" for more details.
Once your mold is created from a cast of your original print, you can quickly and easily start to create multiple copies with a food-grade urethane. Just pour in to the mold and wait for it to dry based on the instructions. These casts will look MUCH better than the original 3D print (if you've done your work to sand and smooth your print properly) and they will be safe to use assuming you used a food-grade material!
Conclusion
Overall, 3D printed objects in their raw form are not technically considered "food safe". While in all practicality, 3D printed items may be OK to use minimally, the safest bet is to post-process prints a bit or utilize "upcycling" to make sure they are as safe as they can be.
ABS plastic is possibly more dangerous than PLA filament, but it still appears to be unknown whether or not these materials can be harmful over time.
At the end of it all, I personally prefer to play it safe and not use 3D printed items with food.