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Printing finished parts for outdoor use

I would like to print some parts for Garden scale railroad models but am concerned about the durability of resin parts. None of the documentation of the resins mentions outdoor applications.

  1. What resin would be most likely to remain stable if exposed to hours of direct sunlight and freezing temperatures?
  2. What type of coating should I apply to the parts to help protect them?
    Any other tips/suggestions would be greatly appreciated.

Unofficially, I think Durable would be your best bet for outdoor Garden-scale railroad parts. It won’t hold the fine detail of some of the general-purpose resins, but it might not need to at Garden scale. The greater flexibility and impact resistance of durable will give it a longer life in the sunlight and in cold temperatures, even if they do make it more brittle than it normally is.

Any paint or coating that blocks sunlight will help prolong the lifetime or the parts; the more opaque the better, so anything heavily pigmented with pigments that don’t afde. UV-blocking products like ones from Armor-All might also help to some extent.

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Thanks Ike for your prompt reply. Actually, one of the reasons I ask is because I would like to produce finer details without the struggles of smoothing FDM materials. I am curious as to what happens to something like the standard resin when exposed to the outdoors. Will it shrink? warp? crumble to dust? I read in another forum that the standard resin is intended for prototyping only and the parts are not expected to last long.

I have had grey V2 resin parts outside for two years without paint surviving very well. They have been out in the sun b but weren’t brittle at all. No warpage too. However, these parts were pretty solid so that might have helped.

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The resin are fairly resistant to most chemicals, this is documented in each resin’s TDS. It is also an inert material so it won’t noticeably “degrade” over time although it might become more brittle with time, which is easily offset by using a UV-blocking coat(most acrylic-based clear coats are uv-blocking, for what it’s worth).

For static use (no mechanical solicitations), standard resins will work without issues. However, they will be very brittle at lower temperatures.

For dynamic use, if the parts will be grabbed or handled by hand or otherwise mechanically stressed the main worry if again brittleness at lower temperatures, and in that case Durable is the best candidate as Ike suggested, although it’s not the most precise resin so it really depends on the type of part you want to make.

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Thanks for your reply. I assume by “solid” you really mean thick? Most of the structure of a G scale model train is about 4-5mm thick. Do you suppose that would need to be “beefed up” to survive outside?

That’s about the thickness I used. 5-10mm. It was very hard to break after two years outside! I was pretty surprised as it was in the sun all summer(20~30C) and winter @ -15C.

Good point: The pigment in Grey resin is also going to be helpful at reducing UV-related degradation. So there may be no one best resin. I’d still say Durable if the part is going to see variable loads, impact, or vibration, especially for big shells, but small compact parts should be fine in most resins. If one needs something to hold a steady force and not creep, one might consider Grey Pro and/or Rigid, because Durable could slump under load in hot weather, and depending on the part, regular Grey, White, or Black might not be strong enough.