I printed an object with a 3D printer and I used a roll of light green ABS plastic filament.

I would like to use the dishwasher to clean it. The temperature would be kept below 70°C, well below the glass transition temperature of about 110°C.

The dishwasher uses standard tabs, not one of the phosphate-free tabs.

What would be the effect of said cleaning on objects made of ABS plastic?

  • $\begingroup$ Well, what do you expect? $\endgroup$ – Karl Jan 12 '20 at 21:31
  • $\begingroup$ The plastic could be degraded, since I remember that setting the wrong water hardness can, after some time, even render glass opaque. I don't know chemistry well, obviously. $\endgroup$ – FarO Jan 12 '20 at 22:05
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    $\begingroup$ If you are planning to wash it by itself in the dishwasher, there is little risk in testing whether it is OK (at least if you can make more than one version). Try washing a model of the same material you can afford to lose and see what happens. don't use it for food or alongside things used for food. Testing is cheap and, if the risk is low, quick and easy. $\endgroup$ – matt_black Jan 13 '20 at 10:31

According to several application guides/compatibility charts for ABS plastic (like this one), ABS is fairly resistant to the conditions present in a dishwasher (mild to strong alkaline, salts, no organic solvents, mild temperatures).

Please note that while the ABS structural backbone may be attacked by nucleophilic agents at the nitrile carbon, and that the nitrile group may be hydrolised in acidic or basic environments, the conditions required are much harsher that a common dishwasher.

For example (p.8), glacial acetic acid was found to cause significant swelling, while 25% w/w sodium hydroxide and 25% w/v HCl barely caused changes.

So, while the concern for release of toxic additives present in the formulation of the original ABS filament may or not be significant, from the chemical point of view it is almost sure it won't degrade noticeably.

Also, anecdotally, I used to wash old LEGO pieces in a dishwasher (kids are dirty), and not degradation was observed at all.

  • $\begingroup$ Also, experimenting with a replaceable sample, as noted before, is a very practical way of getting results. $\endgroup$ – Flyingfenix Jan 13 '20 at 19:09

ABS isn't food safe so you may introduce toxic particles to your dishwasher and anything else in it. The combination of high temperatures and harsh chemicals could still degrade unprotected ABS despite temperatures being below glass transition. Other people have done it before and haven't had issues though, but I prefer to err on the side of caution.

I would recommend using PETG filament over ABS for food-related prints, PETG is less toxic and still handles heat well. You can also anneal PLA to make it more heat resistant but PETG would still be better than annealed PLA.

This question would probably be better answered on a dedicated 3D printing forum rather than on here.

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    $\begingroup$ A recommendation for a filament would indeed go to 3D print SE, but I was asking specifically about the behaviour of ABS because I wanted to keep the question in topic with the Chemistry section, since I expect more knowledge about the degradation in this community. $\endgroup$ – FarO Jan 13 '20 at 10:25
  • $\begingroup$ Although the Flyingfenix's answer goes into good detail of ABS's ability to withstand dishwasher cycles, I would warn against trusting evidence based on more ideal samples. FFF 3D printed parts are much more porous with many more microscopic defects and contaminants than injection-molded ABS, so that's something to keep in mind. $\endgroup$ – Sigma Jan 14 '20 at 11:05

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