Weather resistant 3D printing? How about ASA...

I've been experimenting with 3D printing for a little over 6 months now. Many of the results of my work have found their place on my outdoor layout already. And some of them dramatically affected the way my miniature world looks.

The street lamps are the best example here. When equipped with an LED light source, they've become the essence of the night in my little town.

The street lamps were created in two steps:

• First I printed a set of classic lamps for the train station based on an external project.
• Then I designed my own modern lamps and filled the streets with them.

In all these attempts I've been applying the simplest printing technique and the filament that was easiest to use. That material was PLA and I was always wondering how weather resistant it was. Well, I do have some knowledge about that now...

As soon as the first hot summer days hit, my PLA-based lamps started failing. In particular they've proven not to be resistant to the heat at all. They bent towards the sun very quickly and created the following view...

What's easy to notice here is that the black lamp bent most, followed by the dark gray and then the light one. Black material probably absorbs the heat much more and is therefore affected to a larger extent.

The lamps are not the only example. I've printed a black piece of a pavement and placed a pair of figures on its surface. The two below photos were taken a few weeks apart. It's clear the pavement element warped in a wavy fashion and even caused the postman figure not to stand straight anymore.

This needed a solution since PLA was clearly not the right material to use for a garden layout. My investigation led me to another kind of plastic which was specifically designed for outdoor use. That material is called ASA.

Luckily ASA is already available as a 3D printer filament. It's not easy to get and it requires a much more complicated printing procedure. But the specification states its "glass transition" temperature is around 40° Celsius higher than PLA's and that should be enough to resist the sun heat. The Wikipedia page confirms those facts listing automotive as one of the industries that benefit from ASA use.

So once I got my first batch of ASA filament, I decided to re-print my black lamps. Those were affected most and should make some good test subjects. I also used this opportunity to play a little with the 3D design, but that's a completely different story.

My new ASA-based lamp posts were installed in the evening. In the photo below they can be seen in the front with the old, already bent light-gray PLA lamps in the background.

Over five weeks have passed. There were numerous hot days during that period. Let's see how the ASA plastic did in the summer outdoor conditions...

Well, they seem to be pretty straight. I can't really see any bending or warping here. And actually I can even see that the PLA based lamps in the back of the photo have continued deforming during that period. That would be a proof the test conditions were adequate.

So it turns out that a more weather resistant filament is not only needed for outdoor use but also makes an immediate and visible difference. PLA can still be used but only for objects featuring a more solid structure. The outhouse or the boat I've printed with PLA months ago are doing just fine. But lamps that are composed of a heavy head installed on a thin post are a subject to failure.

I'm switching to ASA printing now. I will be printing the rest of my lamps with this material only. And as for the lamps I already have... well... I guess they need to be replaced :(