In September 2016 I was asked how long 3D printed filament last in the outdoors. I did not have a ready answer for that question, and I could not find any research that addressed the question.

Almost all 3D printing has been sold to the public as a more environmentally friendly alternative to commercially made plastic items. Some filaments like PLA have been touted as almost biodegradable, and sourced from waste products, as a result reducing their carbon foot print.

The Filament Experiment

Three years ago I printed a set of two sample chips for all the filament that I had on hand at the time. After securing them to a 2 x 4 pine board with deck screws, I placed the board on a north facing fence.

In previous blogs  I compared how each sample changed over the months.

About 4 months ago, I had an issue with squirrels knocking the test board off the fence. Because of this I did tie the board onto the fence, however the damage to some of the filament samples was done. As a result, after 3 years It was time to bring in the board. Following that I changed out the broken filament sample chips and added new materials.

In conclusion, here are the results of the test after 3 years of exposure in Colorado.

Material	Changes	Material	Changes
Proto Pasta Aromatic Coffee High Temp PLA	Lightened from brown to tan. Back side was light brown. Removed from the board.	Ninja Flex	Darkened, still flexible
Proto Pasta Conductive PLA	Some cracking.	Semi Flex	Darkened, slightly stiffer
Proto Pasta Polished and unpolished stainless steel	The luster was gone from polished sample. Both faded to a light gray.	Buzzed (beer based PLA	Honey iridescent brown to dull yellow / mustard.
Protopasta Magnetic iron PLA	Both lightened. On the polished sample, it did rust slightly more than the raw sample.	WoundUp (coffee based PLA)	Lightened to tan. Removed from the board.
ColorFabb Transparent Green PLA	Lightened.	GlassFill (Fiberglass based PLA)	Lost luster.
Colorfabb clear XT	Yellowed and foggy. Removed from the board.	3DDPlus PLA	Lightened and lost luster.
ColorFabb Leaf Green PLA/PHA	Lightened	Nanodax GWPP	Brittle, broke easily. Removed from the board.
GlowFill PLA/PHA	Still glowed brightly.	MakerBot PLA	Lightened
Polished and unpolished BronzeFill	Lost luster of polished original.	Wenton PVA	Dissolved after 8 months, left residue on board.
Polished and unpolished CopperFill PLA:	Polished sample dulled.One broken sample removed from the board.	Esun PLA	Lightened
ColorFabb Carbon Fiber	No noticeable change	Esun ABS	Lightened
ColorFabb red nGen	No noticeable change.	INprinting Hemp-based HIPS	Went from white to manila, fibers stood out from material.
ColorFabb WoodFill	Bleached to light buff color.	MeltInk PLA	Despite cracked sample, color remained. Removed from the board.
ColorFabb CorkFill	Bleached to light buff color.	Prototype Supply PLA.	Significant fading to a very pastel pink. Removed from the board.

Table 1. Trends in outdoor survival after 3 years of exposure.

Filament Results After 3 Years

Despite being a black color that absorbed the most light, the carbon fiber and graphite filaments seemed to withstand the elements the most. First of all this was a surprise, as I expected the filament to fray with exposure.

Almost all other filaments experienced color fade to some degree. Premium brands of filament like ColorFabb tended to fade the least, while in contrast off brand filaments tended to fade the most. Similarly all the filaments also became more brittle, while a few sample chips broke after the squirrels knocked the board off the fence.

Most noteworthy the coffee based PLA filaments both turned to a light tan color. As a result outdoor use may not be the best application. However when I changed the samples out, I did notice on the backside that they still had a brown color. Hence I still can’t see coffee based filaments as a viable outdoor filament.

 

Even more the wood and hemp based filaments had a raised grain texture. The color on the HIPS / Hemp had yellowed from the original eggshell white; while the wood based materials became sun bleached. As before when I examined them closer, the back side of the samples kept some of their color. Above all the wood and fiber based filaments weather like the natural form of their source material.

New Filament Materials

Even after 3 years of 3D printing, it seems like the market has exploded with new polymer filament materials. When I started 3D printing, ABS and PLA seemed like the market leaders. Because now if a filament company wants to compete, consequently they have to make new polymers and composites to attract buyers.

On the board I’ll swap out the broken samples and replace them with the following materials.

New Materials List

1.  ColorFabb HT (white) & PETG (Red).
2.  Esun PVB (Natural), PETG + Carbon fiber (black), PC + ABS (white) and Brassfill (Polished and raw).
3. CC Products Laybrick (limestone white)
4. Dikale PLA (white)
5. Kanesis Hemp (Cardboard brown)
6. Taulman n-vent Nylon (blue)
7. Proto Pasta HTPLA v3 (black).
8. 3D3RMT PET bottle Plastic (green)

Predictions

Based on what I have observed, I’ll make the following predictions as these new filament samples are exposed to the elements.

For Kanesis Hemp, I suspect it will bleach in the sun like the ColorFabb wood composites.

The 3D3RMT PET was brittle and difficult to 3D print with from the start. The predict that the sample will be crack and brittle within a years’ time.

All others i predict will fade and lose their color.