How should I finish a food safe print?

Question

I'd like to print a mouse shell from food safe PLA.

I need it to be food safe, because sweat can dissolve any harmful chemical from it just like foods. I am not sure about how to finish it after sanding the result. I read that people use food safe epoxy to seal it before painting to get a smooth surface. I read that others seal it after painting to cover the paint, which is possibly not food safe.

So I am not sure if I should seal it before or after painting or maybe both? I read that some people use shellac or even nail polish instead of epoxy to get something that they think is food safe. So the entire topic is starting to get somewhat chaotic for me. What materials should I use for sealing and painting and in which order?

Answer 1

If you're using food safe PLA, there are no "harmful chemicals" soluble in sweat. The food safety issues that remain are surface imperfections where bacteria or mold may grow. These are almost certainly not an issue unless you're actually eating from the object or otherwise putting it in your mouth/body. People touch similar objects and have them in contact with sweaty hands all the time - athletic equipment, bicycle handlebar grips, steering wheels, etc.

For a user with serious medical issues affecting their immune system, this still may be an issue and you need to follow whatever instructions medical professionals have given about contact with objects that may be contaminated. But otherwise there is no need for any coating for a mouse shell except for aesthetics. You can use whatever you like, but be aware that, unlike PLA, most coatings do involve moderate to high levels of VOC (which are ideally down to non-harmful levels after it's finished setting/curing).