Eco-friendliness has always been a selling point in the 3D printing industry, and today there are many recycled filaments available. Over the past few weeks, I tested a few spools of Sunlu Recycled PLA filament, learning all about the material’s properties so you don’t have to.
Overall, Sunlu Recycled PLA is a great option for eco-conscious makers looking for an easy printing experience without sacrificing strength.
The recycled PLA filaments are surprisingly strong, making them great for printing household items like utensil organizers and certain functional models, such as small gears.
However, one problem I had with Sunlu Recycled PLA was the filaments’ hygroscopy. The filaments absorbed moisture from the air like a sponge, and I started to notice moisture-related print quality issues after leaving the filament in the open air for just a few days.
Regardless, Sunlu Recycled PLA is still a terrific filament option, and I’ll definitely be back for more. So keep reading if you want to learn more about this eco-friendly filament!
Sunlu Recycled PLA: Summary
Below, I’ve provided a quick run-down of Sunlu Recycled PLA.
- Easy to print: Not very sensitive to slicer settings
- Comes in a handful of colors
- Performs great with small layer heights
- Not very hygroscopic (drying is optional)
- Very durable (high tensile strength and elongation)
- Not truly recycled (just repurposed waste)
- Poor performance with larger layer heights
- Low-quality overhangs
- Stringing is prevalent for higher printing temperatures
Background: What Is Recycled Filament?
Before we enter the bulk of this review, it’s important to understand what recycled filament is exactly.
Generally, the term “recycled filament” refers to 3D printing filament that’s been sourced from the industrial scraps of a manufacturer’s regular filament production process.
Moreover, filament manufacturers usually end up with a lot of excess raw materials that don’t meet the manufacturer’s quality standards. This scrap material is separated from the rest of the raw materials and usually ends up in a landfill.
However, some companies, like Sunlu, collect the scrap and use it to produce “recycled” filament, which they sell at a steep discount.
So, no, recycled filament is not actually made from recycled goods like thrown-out plastic bottles. However, recycled filament still can be considered eco-friendly as its purpose is to prevent unnecessary landfill waste.
Finally, before I get into the testing process, it’s worth noting that this review article encompasses three different variations of Sunlu Recycled PLA, including the standard option, PLA-Meta, and PLA-Matte. While each of these variations differ slightly in their properties (e.g. surface finish, print settings), they are all similar enough to compare side-by-side.
Testing & Results
The best way to evaluate a 3D printing filament is to test it! And that’s exactly what I did!
After a few initial prints to make sure the filament was actually usable, I printed 5 different models in Sunlu Recycled PLA and recorded the results in the subsections below. Each model is meant to test the filament in a different way, like the strength, accuracy, overhang quality, and more.
Keep in mind that the quality of these prints depends on many factors besides just the filament material. I did my best to keep the printing conditions consistent, and I printed all of the models on the same Creality Ender 5 S1.
Now let’s get into it!
Test #1: 3DBenchy
My first print, like always, was a standard 3DBenchy. I printed the model using Cura’s default “Standard” profile, with the only change being lowering the nozzle temperature to 190 °C.
As you can see, the print turned out terrific! Even the letters on the bottom of the model came out looking pristine, though it might be difficult to see it in the images. And the overhangs also look very nice with no drooping or sagging in sight.
Of course, it’s not perfect. There are some signs of stringing (due to the printer) and even a hint of stringing, but for the first attempt, I couldn’t ask for better.
- Layer height: 0.2 Mm
- Nozzle temperature: 190 °C
- Print time: X minutes
Test #2: Temperature Tower
My second test print was this temperature tower, which I used to determine the best printing temperature for Sunlu Recycled PLA filament. To do this, I sliced the model using Cura using G-code modifications that change the temperature at each distinct block.
As you can see, the best temperature for printing this recycled PLA filament is between 190-195 °C, which is about average for a PLA filament, if not on the lower side.
However, it’s important to note that the true best printing temperature will depend on the model you’re printing. For example, if you’re printing a phone case and it needs to be strong, you should use a higher nozzle temperature, like 210 °C. Even though this high temperature will likely cause stringing and over-extrusion on your print, it will create a much stronger and less brittle print because more heat means stronger layer-to-layer bonds.
Conversely, if you’re printing a detailed model that doesn’t need to be strong, a slightly lower temperature, like 185-190 °C, might yield the best results.
- Layer height: 0.2 Mm
- Nozzle temperature: 175-220 °C
- Print time: X minutes
Test #3: Hexagonal vase
My third test print was this hexagonal vase, which I like to use for testing performance with large layer heights and vase mode. Moreover, I sliced the model with a 0.28-mm layer height and used Cura’s vase model (“Spiralize Outer Contour”), but the results I got were not exactly what I expected.
First off, the use of a larger layer height sped up print time dramatically. The entire model took under 2 hours to print, which is unachievable using a normal layer height (e.g. 0.2 mm), where it might take 2.5-4 hours.
While the speed was there, the quality of the print was lacking significantly. The larger layers struggled to adequately bond and, as you can see, some sections show some obvious layer sagging. These problems are likely a result of using such a low nozzle temperature (195 °C) and minimal cooling, but some of the blame definitely goes to the material itself.
I also printed the model in a smaller, 0.24-mm layer height and faced basically the same problems. Because of this, I don’t recommend going above 0.2 mm for the layer height when printing Sunlu Recycled PLA filament.
- Layer height: 0.28 Mm
- Nozzle temperature: 195 °C
- Print time: 1 hour 47 minutes
Test #4: Gear Fidget
My fourth test print was a 4-piece gear fidget, which I found on Printables and loved at first sight. The mechanism comprises four 3D prints (two sets of 2 models), which fit together without any real assembly.
Printing all of the pieces at once took just over 4 hours, and I loved the results. The main reason I chose this model was to see how the material handled more precise geometries, and I used a 0.16-mm layer height to test this.
The gear pieces came out beautifully, and while the frame parts had a lot of stringing, I was using a higher-than-normal printing temperature, which was likely the culprit of this problem.
I also tested the strength of the material using this model, which I’ll talk more about later, but it definitely passed my test.
We also have an article on other 3D printable gears for more project options.
- Layer height: 0.16 Mm
- Nozzle temperature: 215 °C
- Print time: 4 hours 9 minutes
Test #5: Simple Hinge
Lastly, I printed a simple hinge in Sunlu Recycled PLA to test how the material handled print-in-place mechanisms. And, further improving my impression of the material, the hinge functioned right off the print bed.
Besides the internal mechanism, the hinge has a very simple design, so it also didn’t surprise me when it came out looking as clean as could be. Overall, a successful test to say the least!
- Layer height: 0.2 Mm
- Nozzle temperature: 195 °C
- Print time: 59 minutes
Material Properties & Findings
Using the test print results and my other first-hand observations, I’ve made a few conclusions about Sunlu Recycled PLA and its properties. I’ve organized these insights in the subsections below.
Strength & Elongation
PLA is generally considered a very weak and brittle filament material, and PLA 3D prints tend to break very easily when pulled apart. However, the strength of the prints made with Sunlu Recycled PLA took me by surprise.
Specifically, I’m speaking about tensile strength and elongation of the filament, which are two similar measures of how much you can pull an object apart before it breaks.
I tested my theory by trying to pull the gear fidget (test print #4) apart to see if the frame piece would break as I expected. But, instead, the part stretched a noticeable amount and then recompressed once I stopped pulling, indicating this material has a high elongation at break.
So, though PLA filament isn’t recommended for printing functional, high-strength models, I’d say Sunlu’s Recycled PLA is an exception as it’s very durable.
One recurring issue I faced when printing Sunlu Recycled PLA was stringing. Stringing not only hurts the visual aesthetic of your model but it also affects the dimensional accuracy, as those small whisps of excess plastic alter the exact size of your model.
I was able to eventually handle the stringing problem, but I had to significantly lower the nozzle temperature, and this, unfortunately, worsened the strength of prints due to weaker layer-to-layer bonds. Moreover, when printing at higher temperatures, like 220 °C, stringing was prevalent, but dropping to 190-195 °C almost completely fixed the problem.
Next, I want to point out that this set of PLA filaments struggled a bit when faced with overhangs. While it wouldn’t be fair to blame all of the overhang issues on the filament itself, I was able to achieve much better overhangs using the same slicer settings with other filament materials.
Because of this property, you should consider activating supports for prints with even small overhangs to ensure the print doesn’t fail when using this filament. Increasing your printer’s cooling settings (e.g. fan speed) can also help with printing overhangs.
Easy to Print
Finally, I’d like to point out that Sunlu Recycled PLA is relatively easy to print. In other words, the material isn’t hyper-sensitive to the slicer settings, so you can achieve decent 3D prints without spending hours and hours tuning your settings.
My first print was very impressive given that I used the default Cura settings for PLA, and they only got better as I continued adjusting my settings.
Optimal Print Settings
As with any 3D printing filament, it’s unlikely that you’ll achieve perfect prints using your slicer’s default settings. Luckily, I already spent over 3 hours analyzing prints and trying new settings so you don’t have to.
I’ve listed the optimal print settings for Sunlu’s recycled PLA filament in the bullet points below:
- Nozzle Temperature: 195 °C
- Bed Temperature: 60 °C
- Layer Height: 0.2 mm
- Print Speed: 60 mm/s
- Infill Density: 10-20%
- Infill Pattern: Cubic (any will work)
- Retraction Length: 5.2 mm (and 2.1 mm for direct drive printers)
- Retraction Speed: 45-50 mm/s (depending on stringing)
Of course, the quality of your prints isn’t only dependent on the slicer settings so don’t worry if these settings don’t produce the results you’re looking for right off the bat. You’ll likely have to tune your slicer on your own a little bit, but, hopefully, these settings are a good starting point.