PETG filament and food safety of 3D printed objects
The PETG and the PET are very similar plastics and it is known that the latter is widely used to produce plastic food containers. This is because both are certified by the FDA to guarantee the safety of the food coming into contact with these materials.
While this is true, it must be understood that the certification refers to the pellet (the raw material) from which the PETG filaments are produced and that certification doesn't apply directly to the printed parts, for different reasons that we are going to analyze.
First, the 3D printing filaments often contain additives to provide them with characteristics that improve their performance when they are used.
The inclusion of any additive that does not have FDA Food Safety certification voids it.
On the other side, most of the filaments are mixed with dyes to give them color and although these dyes are certified ROHS, that is not the same that FDA Food Safety certified.
The first (ROHS) certifies the absence of harmful elements (such as lead or mercury), while the second certifies the absolute safety of the certified object to the extent that it may be in contact for a long time with food intended for consumption.
Therefore, the mere addition of non-FDA Food Safety colors also would void the certification.
Even in the case of filaments whose base material, additives and dyes are FDA Food Safety certified, the process of printing on a domestic machine prevents the resulting object from maintaining the certification.
This is a consequence of the metals on nozzle (brass) and the extruder that pushes the filament are made of.
For all of the above it is not possible to print objects with an FDM printer that comply with FDA Food Safety requirements. If you print parts for others you shouldn't advertise them as Food Safety, no matter that the filament used is PETG or Food Safe PETG.
So, in case you plan to print some object meant to be in contact with food, do it under your own risk.
However, while 3D-printed objects cannot be FDA-certified, it is safe to assume is not harmful to eat a cookie that has been cut with a 3D-printed cookie mold.
So, if you decide to print some part that will be in contact with food in some way, please take in count these tips:
- 3D FDM printing tends to leave small spaces and interstices on the surface of the pieces that favor the development of bacteria and microorganisms. If the piece is to be of single use it may not be a problem but if it is to be reused consider applying a Food Safety epoxy coating to seal the surface of the piece.
- Such organisms should die when using a dishwasher because of the high temperature of the water but such temperature can deform the part.
- The contact time between the food and the piece is important; a bottle is not the same as a fork or a cookie cutter. So, the shorter the part is in contact with the food, the safer.