Review – SUNLU Rainbow Filament

Rainbow filament

My recent experiment with changing filament colours got me thinking. I’ve seen multicoloured filament on sale quite a few times, and wondered how it compared to my own efforts. As you know by now we’re practical people at 3D Printing UK, so instead of thinking about it too much we immediately ordered a spool of rainbow filament and got printing.

So What Is It?

What we got was a 1kg spool of SUNLU silk-effect PLA+ rainbow filament. This goes for £23.99 on Amazon, which isn’t a lot more than a roll of basic PLA, so it’s a fairly economical filament.

What sets it apart from standard PLA is that it isn’t all the same colour. In fact it’s five colours – gold, green, blue, purple and pink. These aren’t different-coloured filaments joined together, either. It’s a single length, with the colour change added by changing the colour of the feedstock being fed into the extruder. That also gives a smooth, graduated change between the colours. When you print something with this you’ll get bands of colour that blend into each other with no abrupt transitions.

Well, that’s the idea, anyway. Let’s see how well it works out.

Start With A 3D Benchy

When you’re testing anything 3D printer-related, you can never go far wrong with a 3D Benchy. I did suspect that printing a standard one was going to be a bit short on colour changes, though, so I elected to go for one of the super-size Benchies I used to test supports a few weeks back. That, I was sure, would use enough filament to get some nice coloured stripes.

Well, it didn’t. What I ended up with was a gold Benchy. The lower hull was gold with a strong hint of green; the wheelhouse roof and funnel were rose gold. But this was, unmistakably, a gold Benchy.

I’m going to detour from colour to filament quality for a moment, though. It’s an extremely nice gold Benchy. In fact it’s the nicest Benchy I’ve printed yet. The print quality is just excellent, and the silk-effect filament gives a very attractive semi-gloss surface finish. This is really nice filament and turned out a beautifully 3D printed object with no bubbles, stringing or other glitches. It’s just, well, gold.

Supersizing It

Undeterred, I looked for something bigger to print. My mother is coming down to visit next weekend and she’s always growing flowers in her garden, so I decided I’d make her a vase. I dug out the spiral vase model I used to test our first batch of decorative filaments, scaled it up as much as the Ender 3 can handle, loaded it onto a TF card and hit the start button.

Then, almost two days later, my filament guides got jammed and the print failed at 82% complete.

As you can imagine I was somewhat annoyed at this. What I pulled off the bed was a big vase, but the top was very rough-looking, with the infill visible in the gap between inner and outer walls. After a few minutes I stopped swearing, though, and realised I could salvage it by designing and printing a snap-on ring to cover the top. That came out in an attractive gold colour, and fitted neatly in place.

Yes, the ring is gold. The vase is big enough that the spool had run through its whole rainbow of colours and got back to the start. So how does it look? Well, like this:

The Verdict

SUNLU rainbow PLA+ is a very nice filament that produces high-quality 3D prints. It fed flawlessly in the Ender and, with a 200°C nozzle temperature and the bed at 50°C, gave a great, unblemished end result. The colour change is also extremely attractive. It wouldn’t be any use for printing contrasting surface details on something, as I did with my nozzle rack, but for decorative objects the subtle shift from one colour to the next looks amazing.

The only downside to this filament is that it doesn’t work well on small prints. SUNLU says there’s a colour change every 15 metres, and that seems about right; my Benchy needed 23m of filament, started printing halfway through one colour change and finished halfway through the next. The vase, on the other hand, used about 100m and went through the whole spectrum. If you want to print something large and decorative I highly recommend it.

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