Garden Railway Forum

During last summer I left resin printed figures and post-boxes outside for 2 weeks. Laziness really - but the result was a bit of a surprise.

The post boxes developed large cracks - and sort of exploded - but very slowly. Something similar happened to some of the figures.

I was overhasty to throw the damaged items out - and I can only really share this one with you. It has the early signs of what I am talking about:
You can see the dark cracks along the torso, and the left shoulder.

More recently I have left the row of cottages outside - again for about 2 weeks. This went out as soon as the paint was dry. Look at this upstairs window:
The framing has expanded and fallen apart.

Look at the door in this photo:
The doorstep has curled up, and the door has expanded pushing it into the building. On the other hand the filament printed window next to the door is perfect.


I could show you lots of things which have been outside and not deteriorated in any obvious way - but the difference is that they have not been left outside for any length of time.

So what can I tell you which will help to shed light on this. Firstly I have used different resins over the past 18months and I cant really be sure what was printed using which resin. I was using a cheap uv Lamp to post cure things - and have only recently bought a wash and cure machine. So there have to be doubts about whether I was curing things properly.

All of these things were painted with acrylic primer, and 2 coats of acrylic paint, mostly airbrushed.

At the moment I suspect that resin printed models/components, can't be left out in the weather for any length of time. However it would be reassuring to hear that others had had different experiences.

Trevor

How thick are these items? Unintuitively, resin seems more robust for thin sections rather than thick or solid items....I suspect this is because the inside takes a really long time to cure especially with darker resins. Prolonged UV exposure will cause internal stresses.to develop leading to cracking of brittle materials.

If I was planning on leaving something outside I would use a light colour resin, preferably not too brittle and make the structure as thin as possible (transparent resin would be good for the former .....for a building, thing more like a real building in miniature rather than traditional model building (IE use a closer to scale thickness wall with pillars / braces etc rather than a uniform thick wall). I would then leave the print outside for a week or so before painting it to allow slow but full curing as far as possible.

Of course all this is based on theory so it's entirely possible that it would still crack eventually!

You may be correct - and in many ways that is what I wondered myself.

The figures which I have which have bulbous skirts were hollowed in the slicing software. These seem to be undamaged so far. I am currently using a gray resin, and I have just placed a hollowed postbox outside.

I will let you know what happens.

Trevor

I've not left a resin object outside for any length of time myself, so haven't seen these effects.

However, having seen the variable time it takes to cure some resins, I wouldn't be surprised if that is at the root of what you are seeing.
I don't know whether translucent vs coloured resin is actually relevant to curing time, but the worst resin I've ever used was Anycubic grey and I've had generally good results with translucent green.

The resin printed post box has been outside in the weather for 2 weeks now. No sign of deterioration so far.

I am fairly sure that my problems were caused by not curing the resin properly in the first place. Having the wash and cure device should make sure that this is a problem of the past.

I am currently using an own brand "ABS like" resin from Technologyoutlet.co.uk which seems to work well. Strong stable and takes drilling and filing well.

Trevor

Trevor Thompson wrote: ↑Fri Dec 09, 2022 12:17 pm

I am currently using an own brand "ABS like" resin from Technologyoutlet.co.uk which seems to work well.

Just tried to find it but doesn't appear to be on their site? There are several own brand resins but none described as "ABS like".

philipy wrote: ↑Sat Dec 10, 2022 5:08 pm

Trevor Thompson wrote: ↑Fri Dec 09, 2022 12:17 pm

I am currently using an own brand "ABS like" resin from Technologyoutlet.co.uk which seems to work well.

Just tried to find it but doesn't appear to be on their site? There are several own brand resins but none described as "ABS like".

Amazon do a "like ABS" resin as I have previously used it. I don't recall the brand.

-steves- wrote: ↑Sat Dec 10, 2022 7:08 pm

Amazon do a "like ABS" resin as I have previously used it. I don't recall the brand.

There are loads with that description, but also some lousy reviews, which is why I was interested in Trevor's recommedation.

I use this one

Amazon Brand -Eono ABS-Like 3D... https://www.amazon.co.uk/dp/B091C4XVGC? ... b_ap_share

It's a lot less brittle than most resins and gives good results.

Please forgive the "non garden" scale model but hopefully gives an idea of the results that can be obtained (and a 16mm scale version is on the cards too after the b class is finished)

-steves- wrote: ↑Sat Dec 10, 2022 7:08 pm

philipy wrote: ↑Sat Dec 10, 2022 5:08 pm

Trevor Thompson wrote: ↑Fri Dec 09, 2022 12:17 pm

I am currently using an own brand "ABS like" resin from Technologyoutlet.co.uk which seems to work well.

Just tried to find it but doesn't appear to be on their site? There are several own brand resins but none described as "ABS like".

Amazon do a "like ABS" resin as I have previously used it. I don't recall the brand.

Yes I couldn't find it either - but I assume it will be back in stock sometime. The other one I got from the same website was an "engineering quality resin" - their own brand again - but that may not be available at the moment. That also gives me good results.

Trevor