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Priming and sealing a painted print (piefed.social)
submitted 9 months ago* (last edited 9 months ago) by to c/3dprinting@lemmy.world
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I'm about to paint a PLA 3D print for the first time, and while there is some advice on what primer to use (an automotive etching plastic primer seems to be it), I've not see anything but hand wavy "add a layer of clear coat" for sealing.

Does anyone have any advice on a matte finish clear coat product that works well, as much so I know I have the right class/type of product?

Also, is there much difference between the products from hobby shops vs hardware stores? I can imagine the hobby ones are at a consistency for painting fine details, but it may also all be the same thing.

Thanks

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[–] 2 points 9 months ago (2 children)

These are all valid concerns, and I'm happy to throw my 2¢ in, if it helps. I've been printing for a while now, (FDM, MSLA) and even went semi-pro for several years (9 printers, 40+ hrs/wk), but still take this with a grain of salt, of course. Every use case is unique, and there are a wide variety of products and methods out there, so don't be afraid to experiment to find what works best for your project. 🫡

That said, I've had better than average success with Rust-Oleum spray varnishes for all but the most demanding/complicated projects. Be patient (don't rush), keep the coats thin/light, always use PPE & proper ventilation (no joke), and test print whenever you feel the need to try a new tech/process out.

So, first off:

  1. What's the PLA model going to be used for?

  2. How durable does the varnish itself need to be for the intended use of said model?

  3. Are there moving parts that need to be masked before spraying so the clear coat doesn't gum up from friction?

  4. Indoor or outdoor use? (ie. Avg temps, weather, etc.)

🖖🏽🤓

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  • [–] [S] 2 points 9 months ago (1 child)

    Thank you for this. I'm actually trying a Rust-Oleum primer for this, so I'll check out their varnish too. And I'll get setup PPE wise.

    Regarding the print, this one is a pirate chest to be used as a money box for my son. Other than the hinge there are no really moving parts, but I expect it'll get banged around a bit, hence thinking I need the clear coat at all.

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  • [–] 1 point 9 months ago*

    No worries, that seems fairly straightforward overall in that the abutting hinge surfaces could go unvarnished but sanded, (I'd use dot stickers, if you don't feel like fiddling w/ hand-cut tape pieces) followed by a light dusting of graphite (ie. shave some pencil lead into a creased post-it and then sift it onto them [and into the rod's channel, for inc. smooth action]). The rest can be clear coated to your preference. (leave said masking on until this step is complete & dry cured, fyi [24+ hrs])

    FWIW, gloss first and then matte for super durability as IIRC, the gloss particulate is torus-shaped whereas the matte is spheroid, and this method nests them neatly for a better bond. It's how I've sealed my TTRPG pieces for decades, and while possibly anecdotal, the results are night & day in my experience. 🤘🏼

    Oh, and if it needs mentioning: do not construct it fully and then varnish the whole model in one piece. That will glue the thing shut. 🫡

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