Hello! I’d like to print food safe objects to use in the kitchen, like spoons and glasses and so on. Looking on the web it seems that the problem with 3d printed objects is that the space between layers is like bacteria’s heaven, so after one use you have to throw them away. The only way I found on the web is “coat with resin”, but I don’t like this very much, as scratches can remove the coating. also “print a negative and use it like a stamp” seems like too much work for a simple spoon.
so the question is, what if I use a filament that can go into the dishwasher, so I can clean it with boiling water? the web didn’t help me much on this, as I found different opinions on the matter: some people said that PETG could go in the dishwasher, some said no.

what is the real answer? can I 3d print PETG objects, use them, put them in the dishwasher, and then safely reuse them?

  • huginn@feddit.itEnglish
    0·
    10 months ago

    Nonoilen filament printing is what you’re looking for.

    It’s a pain to print with and I suggest you just don’t print food safe objects.

  • Nawor3565@lemmy.blahaj.zoneEnglish
    0·
    10 months ago

    The glass transition temperature (the temperature where plastic starts to become malleable) of PETG is 85°C, so if you put a PETG spoon in boiling water, it would deform and become pretty useless. However, if you used a high temperature plastic with a glass transition point above 100°C, you might be able to get away with this method.

    Also, just to clarify, a dishwasher does not get to 100°C. You could use it to get the initial food off, but you would then need to boil the utensils manually on a stove to actually sterilize them.

    • Arcka@midwest.socialEnglish
      0·
      10 months ago

      You can sanitize at boiling, and far below that too. For actual sterilization, you’d need to be above boiling using something like an autoclave or pressure cooker.

  • 👍Maximum Derek👍@discuss.tchncs.deEnglish
    0·
    10 months ago

    To even approach food safety you’d need to do the following

    1. Use a material with a higher glass transition temp than PETG that is also a food safe plastic. You really need to be able to wash in HOT water. I’m not sure if PC blends are food safe, but if they are that might be the way to go.
    2. Ensure that EVERYTHING in your filament path is food safe. E.g:
      1. No toxic lubrication in the feeding mechanism
      2. No possible contamination from other filaments: never use that hot end for anything else.
      3. The nozzle and meltzone are made of food safe materials with food safe production (many brass things end up contaminated with lead)
    3. Seal or smooth: Its not just layer lines. As the plastic cools it will form microcrazing (tiny cracks) that serve as an ideal place for bacteria to hide during washing/sanitizing. Even if you use a material that can go in the dishwasher if those cracks are still there you’ll still end up loaded with bacteria/fungi/mold.