alt Hacker News> I personally am not fond of eating hot degraded PTFE
If this is a problem, you should buy a new printer that actually keeps the filament conduits away from the hotend. This is a health hazard regardless of food safety - decomposed PTFE is nasty stuff to breathe in.
> Or the trace remains of charred ASA/ABS I printed last week through the same nozzle...
Fair enough, but I would also say that you should be purging old filament anyways before starting a new one. My slicer does this by default.
> Or in fact any of the various coatings of the heated bed or leftover trace amounts of previous prints...
These days, heated beds are covered in PEI. That's food-safe too.
I think your take is a little panicky and not supported by the evidence. It is perfectly fine to print single-use food stuff out of PLA, especially if you just have a roll or two of the pure (undyed) stuff around. You're much more likely to get sick from the food itself than the plastic it touched for a little while, and PLA is relatively biodegradable compared to most other plastic foodware.
> If this is a problem, you should buy a new printer that actually keeps the filament conduits away from the hotend
The filament is still in contact with the PTFE tube, the PTFE tube is also hand-cut by me and in motion with the head so it undergoes wear. Even when you get an all-metal hotend there are ways of contamination by PTFE passing through the hot-end and degrading into harmful chemicals.
> purging old filament anyways before starting a new one. My slicer does this by default.
I do purge and cold-pull. While this removes the bulk of the old filament it does not remove all trace amounts of it.
> These days, heated beds are covered in PEI. That's food-safe too.
It is food-safe only if it was produced in a food-safe manner and was kept food safe afterwards, including no contact with pollutants.
Since you mention evidence, I have no way of proving that anything I produce is food-safe. Literally not anything in my extrusion path is certified food-safe, let alone I have equipment to test.
The fact of the matter is that glass, ceramic, and stainless steel has replaced any vessels that are in contact with food at home, and I don't intend to look back on that, and I am in fact looking to replace anything in regular contact with human skin with non-synthetic/non-plastic alternatives -- this includes clothes, bed sheets and others.
While there is the hacking mindset, people also need to be responsible, and my red lines on that is making stuff with a safety aspect to it. Food safety is safety as much as fire and electrical safety in my book.