A lot of the ‘prosumer’ – for as much as I hate that word – 3D printers out there like the Makerbot Replicator and countless other Kickstarter projects only officially support PLA filament. This has a few advantages from a product development standpoint, namely not necessitating the use of a heated build plate. There are other reasons for not supporting ABS and other filaments, as one of the Kickstarter updates for the Buccaneer printer elucidates (update available to backers only, here’s a mirror from somebody on reddit).
The main crux of the Buccaneer team’s decision not to support ABS is as follows:
We spoke to our legal counsel about it and they told us that if we officially support a certain “material” type then our printer has to go through massive certification to prove that it is totally safe to use or we will/can get sued badly.
Despite the Buccaneer team’s best efforts, we’re sure, their lawyers were actually able to find some studies that showed ABS could affect a person’s health. The issue isn’t with the ABS itself – LEGO are made of ABS and kids chew on blocks all the time. The issue comes from the decomposition of ABS when it is heated.
Oh wow actual studies.
There are a few studies referenced by the Buccaneer team’s update, so we’re going to go over these one by one. A few of them are behind a pay wall, so “don’t post a link to them in the comments.” See those quotes? Yeah. If you’re able to download them, “Don’t” host them and post a link in the comments.
This study looked at 140 male subjects at ABS processing plants in Taiwan. Subjects were placed into two groups, those dealing with the big, heavy molding machines, and those who did not work in the same area of these machines. Subjects were tested for olfactory (sense of smell) function using three tests before and after clocking in for one day of work. The results showed a significant (but small) decrease in olfactory function in the exposed group. The TL;DR for this study is, “Being around molten ABS decreases your sense of smell”
This study put rats in a cage and exposed them to heated ABS for six hours a night for several nights. Even the shortest exposures for all groups displayed a decrease in an antioxidant (that’s bad) in the rats’ liver and kidney and an increase in 0-deethylation (also bad) in the lung and kidney. These effects disappeared after two weeks. TL;DR for this study is, “ABS will do things to your lungs, liver, and kidney, but it’s not permanent.” The good news about this study is they have some information on what decomposing ABS actually produces. They saw, “styrene, various nitriles, aldehydes, and acids” coming from hot ABS.
Oh cool, something actually applicable to 3D printers. These researchers went into an “office space belonging to a company who specializes in 3D printer education, training, and sales.” We’re betting someone from this company is reading this right now, so drop a note in the comments. Our curiosity is killing us.
After getting a baseline measurement of nanoparticles with this very expensive piece of kit, the researchers printed small PLA baubles on two printers for 20 minutes. After again measuring the amount of nanoparticles in the room, the researchers used 2 printers for PLA and three for ABS to print a plastic frog for 20 minutes. The room was measured again. After that, they used measured nanoparticle concentrations for 40 minutes to get an idea of the decay time.
There are a ton of data points in this study, but here’s the crappy ‘journalist reading a journal’ interpretation: With the printers off, there were about 2000 particles per unit measured. With PLA printers, there were about 7000 particles per unit measured. With ABS, there were about 25000 particles per unit measured. Note the ABS condition used five printers (three printing ABS, two PLA), while the PLA condition only used two printers). We would question the researcher’s methodology here, but they only had about two hours to design and construct this experiment.
The TL;DR for this study is ABS produces a lot more ultrafine particles than PLA.
There might not be an engineering solution to this
For RepRappers concerned about these ultrafine particle emissions, the obvious solution would be to simply put a printer in a plastic box and run an exhaust vent outside. That’s the cheapest and easiest means of effectively ridding your workspace of ultrafine particles, but for any commercial printer it’s a non-starter. Would you really buy a normal, 2D inkjet printer that required you to run an exhaust line outdoors?
The other obvious solution to this problem of ultrafine particles would be to simply put an air filter on a printer. The Ultimaker 2 already has a door (and the Makerbot works best with a full enclosure). All you would need to do is slap a fan onto the chassis, get some negative pressure in the build volume, and put a HEPA filter somewhere in there. Right?
Well, no. In one of the studies investigating the ultrafine particle emissions of 3D printers, the researchers found squirting ABS generates a whole lot of these particles down to about 15 nanometers. That’s tiny. To put that in perspective, the human HIV virus is about 90 nanometers. HEPA filters are only guaranteed to filter out particles larger than 0.3 micrometers, or 300 nanometers. It’s like shooting a bullet through a chain-link fence.
I wouldn’t worry too much about this
Concerning the olfactory study, the careful reader must note this was not the experimental group’s first encounter with molten ABS. They worked on ABS injection molding machines every day, and when comparing the pre-exposure conditions between the experimental and control groups there was not a significant difference. If you’re around smelly stuff all day, you lose a little bit of your sense of smell. Interesting, huh?
As for the ultrafine particles produced by 3D printers, the authors are very careful to put their results into context. The closest these researchers get to making a proper comparison between exposure, particle size, and other factors, is a study measuring the ultrafine particle emissions of cooking. Comparing the two, printing with a PLA-based printer is similar to cooking with an electric frying pan, and printing with ABS is similar to grilling with a gas or electric stove.
Finally, considering the biological effects of printing with ABS, there simply isn’t enough data. Biology and OChem is hard, yo, and I’m not going to make the mistake of claiming knowledge when I have none.
So there you go
At least one 3D printer manufacturer isn’t supporting out-of-the-box ABS printing because of some studies. If you’re just a home-bound tinkerer, you probably shouldn’t worry about printing with ABS until some more studies are done and rats are decapitated. If you’re a lawyer providing council for a bunch of people starting a 3D printing business, tell them not to support ABS printing. It’s just a CYA maneuver so you don’t get sued.