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  1. #1
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    Skin Safe Plastics?

    I have searched the internet and can't really find a resource that gives a list of plastics that are safe for long periods of skin contact (such as brace or other medical device). I'm fairly sure Nylon is safe, but I was wondering if cheaper materials such as PLA and ABS would be ok.

    Thanks!

  2. #2
    Engineer-in-Training ralphzoontjens's Avatar
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    Hi,

    Nylon is very applicable to wear on the skin - it's the additives such as colorants that may cause irritation.
    I would avoid any polymers with butadiene and styrene components. They are not endemic to the human body and may depolymerize and leech out of the plastic.
    PLA on the other hand has a lactic acid monomer which is present in the human body. It is biodegradable and entirely safe for contact with the human body.
    Also acrylics, silicone, and polyurethanes can be safe for longstanding periods of skin contact.

  3. #3
    Super Moderator curious aardvark's Avatar
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    probably best to look for food contact safe filaments. These have been certified to not leach chemicals into food.
    So unless you have a specific allergy to a particular plastic or chemical, they should be fine.

  4. #4
    Quote Originally Posted by gcm0285 View Post
    I have searched the internet and can't really find a resource that gives a list of plastics that are safe for long periods of skin contact (such as brace or other medical device). I'm fairly sure Nylon is safe, but I was wondering if cheaper materials such as PLA and ABS would be ok.

    Thanks!
    Nylon is not very safe for skin. It is mostly made of petroleum and it often gives a permanent chemical finish that could be harmful to the skin.

  5. #5
    Engineer-in-Training ralphzoontjens's Avatar
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    Hi,
    There are actually tons of articles about this, for example in pathology and biomedical engineering.
    Keywords: cytotoxicity, biocompatibility, erythematous reactions

    What I know is that nylon is much better for skin contact than many other polymers.
    What you also want to look for is a polymer with little hydrolytic effects so it retains its original properties over time.
    Nylon loses a lot of strength when in contact with moisture and acids for prolonged periods. That also goes for PLA and other biodegradable materials.
    ABS is suitable for skin contact, it is also used in the adult industry and tattoo dyes. It is the additives that may cause reactions. Look into the MSDS of your specific filament.
    Also PMMA filament is suitable and has been used in prosthetics for years, skin reactions may occur but will be very rare.

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