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Making PLA 0.15mm smooth, glossy and safer. How well will just resin work? (lemmy.ml)
submitted 4 days ago by to c/3dprinting@lemmy.world
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A friend of a friend makes some useful equipment, and after ordering one of their items, I realized I have some concerns.

  1. This is a tool that will be breathed through (like a short tube, just for regular air) and PLA microplastics are microplastics. I assume coating with a food-safe craft resin should minimize the risk of deterioration or leaching of any additives/dyes if the filament isn't food-safe. Let me know if that assumption has problems.

  2. Ideally, the appearance would be midnight black and highly glossy, at least from a metre away. That said, I don't want to sand it because I don't have access to a workspace, I don't feel comfortable releasing microplastic debris into the air or water just for a small tool, I'm not contaminating my living space with it, and a respirator is an additional cost for a small, one-time project. Will glossy resin alone give a decently smooth appearance on top of unsanded 0.15mm?

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[–] 14 points 4 days ago

No you should not 3d print a bong.

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    [–] 5 points 4 days ago* (last edited 4 days ago) (2 children)

    A nice smooth gloss is actually difficult to achieve. It requires a lot of fill and sanding on the substrate to make a perfect surface for the gloss coat to go down evenly. Your definitely-not-a-bong will reflect every layer line and look super uneven if you haven't done the work to sand and finish the surface underneath.

    Also, I would generally not recommend making something you are going to put in your mouth from a 3D-printer (medical applications aside, which are very different from what's being discussed here). 3D-printed widgets typically aren't food safe, regardless of whether the material itself is generally considered food safe, as the layer lines create crevices that are difficult to clean. If you aren't willing to sand the piece, your resin coat probably won't change that.

    Edit: Another point- you said you don't want to buy a respirator for this project, but expect to work with some sort of resin or epoxy coating. That shit off gasses as it cures, you should really wear proper PPE when working with it.

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  • [–] [S] 1 point 4 days ago* (1 child)

    layer lines create crevices that are difficult to clean. If you aren’t willing to sand the piece, your resin coat probably won’t change that.

    I assumed (without evidence) the resin would tend to level out rather than retain those layer lines, but I suppose the viscosity might affect that and I don't know how viscous the once I'm looking at is.

    e.g. https://www.reddit.com/r/3Dprinting/comments/8mt9vk/comment/dzqxfda/ [comment has before shot, OP has after]

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  • [–] 3 points 4 days ago

    Generally speaking, a coating will conform to the substrate as a function of both viscosity and layer depth. You are right that a more viscous coating is going to be easier to apply and smooth, but it still won't be particularly smooth unless you did the pre-work to get it there.

    That person sanded their print first. There are also some filler-primer paints that will fill the layer line crevices for you, but you still need to sand the surface before applying anything.

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    • [–] 3 points 4 days ago

    You’re better off just casting with food safe resin. Keep in mind that virtually no resin is stable when heated unless you explicitly get a heat stable food safe resin.

    Even “food safe” FDM runs the risk of contamination by mold and bacteria, since it’s quite hole filled even when it may look smooth. All it takes is one hole in the resin and you’ve got a recipe for contamination.

    So, yes. It’s possible. Just keep in mind that you need to be careful. And if just make sure everything involved is food safe, even if it’s encased in the resin. Better safe than sorry.

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    [–] 1 point 4 days ago

    I’m not sure I understand #2.

    Are you wanting to print in resin, or print in PLA filament and coat it in resin?

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