Can I drink from a PLA/PETG cup

[Nathan Hannam]

On a very quick google search I couldn't find anything. I'm sure someone here will know the answer

[Kurt at VRFX]

This has been discussed many times in the past, maybe on this forum, definitely on prior forums.

In theory - PETG is supposed to be the more "food safe".

That being said - the issue is that there are microscopic spaces in the 3D Printing of an object. So, the one problem caused by that is that 3D Printed things will generally leak. I HAVE printed in ABS - and then Acetone Vapor Smooothed the object to deal with that issue of microscopic pours.

The other problem with microscopic pores is that bacteria can grow in them!

So - there you go - a little food for thought...

-Kurt

On 5/28/2022 6:36 PM, Nathan Hannam wrote:

On a very quick google search I couldn't find anything. I'm sure someone here will know the answer --
You received this message because you are subscribed to the Google Groups "3D Printing Tips and Tricks" group.
To unsubscribe from this group and stop receiving emails from it, send an email to 3d-printing-tips--...@googlegroups.com.
To view this discussion on the web visit https://groups.google.com/d/msgid/3d-printing-tips--tricks/5506d0cd-da13-41bc-95ad-850d13f873d2n%40googlegroups.com.

[Ian Nicholls]

In addition to the other replies, the filament path, especially the brass nozzle, might contain lead, and contaminate the filament as it passes through.

That said, I'm still using my PETG coffee measure. Dry goods only, and I mostly smoothed ithe surface using flame.

[Alan B]

People do coat PLA or PETG prints with food safe rated paint or epoxy to seal and separate the print from foord/drink. 

--

You received this message because you are subscribed to the Google Groups "3D Printing Tips and Tricks" group.
To unsubscribe from this group and stop receiving emails from it, send an email to 3d-printing-tips--...@googlegroups.com.

To view this discussion on the web visit https://groups.google.com/d/msgid/3d-printing-tips--tricks/ef3297e7-f51d-48e9-9893-443bf83b2435n%40googlegroups.com.

[Joseph Larson]

The answer to your question is "Yes". You can, and probably have many times, drunk from plastic cups made from PLA or, more commonly, PETG. That a common material for making plastic cups from.

But I don't think that's what you're asking. You're asking if 3D printed cups are safe to drink from, and the answer to that question carries a lot of baggage. First of all, if you just want to print a shot glass and celebrate your success with a drink, many people have done that in the past, and they're mostly still alive and kicking today. (It's been a decade, so, I don't know, we've probably lost a few in that time.) A one time drink from a 3D printed cup probably isn't going to kill you.

I'm disappointed a google search didn't turn this up:

https://www.youtube.com/watch?v=kuyys1YpAVw

However, I do need to update that video. Some of it is still accurate, but there's been a new development in my latest round of experiments. I've done a lot of research and interviews to be able to accurately answer this question, though.

Short version, 3D prints are not food safe, but not for the reasons people commonly site.

Let's take apart the common arguments, some of which we've already seen here, and talk about why they aren't right.

Microscopic spaces where bacteria can breed:

Does 3D prints have microscopic spaces that sugars and food can get caught and that can be a breeding ground for bacteria and other microbes? Maybe. Depends on how you print it. Keep in mind we're talking about FFF 3D printing here. SLA/DUP doesn't run into this problem at all, but SLA/DUP doesn't print PLA/PETG. 

But the think about those spaces are, if food and stuff can get into them, so can soap and water! (Mostly. We'll talk about an exception in a bit.) If you're not washing your dishes, then, sure, they're gonna grow goobers. But if you're not washing your dishes, that's on you! If you're washing your dishes, then you probably don't have anything to worry about. (Again, exception coming up in a bit.)

Lead in the nozzle:

Speaking with a rep from the FDA years ago, they pointed out that it's a question of transference. How much of that lead gets into your body, and whether that amount is enough to be dangerous. The danger level is 12 µg per day for adults, 3 µg for children. That's not much. But, that brass nozzle is no more than 3.5% of lead. So 3.5% of that nozzle is lead, and if the nozzle is only a few micrograms, if you ate a whole nozzle per day, you might be in danger. Assuming you're not in the business of eating nozzles, that nozzle would have to wear down into your print (which maybe happens some), and that lead would have to then be transferred from the utensil to your food, to you. If we were wearing our nozzles out that fast we'd be changing them a lot more often.

Touching lead it not enough. It has to get into you to be a problem. Honestly, the lead is not a problem.

Unknown additives in the plastic:

Again, from the FDA, it's a question of transference. And for limited contact (like a plate, spoon, or cup) there's not enough of whatever you're worried about to get into the food and then into you to be dangerous. Maybe if you used aesbestosfill ABS as Tupperware for months and microwaved it daily, then maybe you're getting a little something dangerous in you. So don't do that. 

If you're just using it for brief contact with the food stuff, you're probably fine. And if you're worried about it, you can use "natural" filament with fewer additives to be safer.

So what's why isn't 3D prints food safe?

In a recent round of tests, I found a new problem that is a legitimate concern. I printed cups, plates, and forks in natural PETG, the safest material I could find, and tried using them as utensils. And I ran into 2 problems. 

First of all, when I put them in the dishwasher, the sanitation cycle warped them. So they failed the practicality test. You can avoid the sanitation cycle and they'll not warp, but they don't get the added level of assurance that the sanitation cycle provides.

Secondly, and this is the big one, the cups leaked. Turns out that "microscopic spaces" question actually reared it's head again and went back to being relevant. See, the layer-by-layer 3D prints left holes big enough for liquid to get between them, and into the infill, before falling back out the outside of the cup. And if that liquid is sugary juice, then, yeah, there's a concern about that space in the infill being a space where soap and water can't get to as effectively and bacteria and goobers could grow. However, you can fix this just by turning up your extrusion rate. By over extruding just a little you lose your printable accuracy, but you gain weathertightness. And if your cup is water tight, then it might be food safe, because, again, now wherever the sugars and foods can get, so can soap and water.

So, there you go, over extrude a little, wash it with soap and water, and use a natural filament, and you'll probably be fine.

But are 3D prints safe by default or in general? No. They can be, but the default answer has to be "no".