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One way to give PLA prints a smooth finish is treatment with chloroform vapours (or other solvents, as mentioned in this answer). This method is even featured on Ultimaker website. I would like to try it on some of my prints.

What are the practical concerns I should be aware of using chloroform vapours? I am looking for advice concerning vaporisation temperature, time of exposition that makes for a nice finish, and any other experiences.

Caution! Chloroform is a moderately toxic chemical! I only approach this method as I have an access to a well-equipped chemical laboratory with a fume hood.

Disclamer: The question is not about the safety issues using chloroform vapours. It is about how obtain the best post-processing results with least trial-and-error.

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This Reddit post seems to have some good trial and error dialog.

This Thingiverse post, along with many other references online, suggest that the results are very similar to that of an Acetone treatment with ABS. I'm not familiar with the inner workings of how it works, but the general advice is to be conscious of what you're working with. A heat-induced vapor treatment seems to yield the best surface finish, but can be tricky to track down proper exposure times. It seems that the time required to achieve a desirable surface finish depends on the size and openness of the features on the object. By openness, I mean how evenly the vapor is able attach itself to the surface of the object as compared to other features. Some this variability may be reduced by streamlining the process. Perhaps if you found a way to rotate either the part or the vapor container during the process. This could ensure contact is made in small corners/features. Other variables to consider may be:

  • If a gradual reduction of exposure is necessary (as is with most heat treatment operations);
  • How much temperature effects time. Most pages I've read mention 100C as the temp to vaporize the chemical;
  • Size of the "vaporization chamber" in accordance with how much of the chemical is available. I've used a gallon paint can lined with lightly dabbed paper towel with Acetone for part between 1"^3 to about 4"^3.

That's all I can think of, currently, that could potentially have the most impact on the process. Just as with 3D printing, there's not an easy way to definitively know how your parts will turn out. The sheer difference in the shape of your parts could throw out any "proven process" you come up with. Hopefully this gives you an idea of what things to look out for in starting out.

Here's information about safety, before OP added disclaimer As with any chemical, always refer to the MSDS (Material Safety Data Sheet)! Whichever supplier you acquire the chloroform from, should ship an MSDS with the product. If one is not shipped, you should be able to request one. If they don't have one, don't use the product and don't purchase from them.

In most cases, you can get away with finding any MSDS online, but I'd recommend trying to get one directly from your supplier as they might theoretically have a different "strand" of the chemical. Therefore, reactions and safety precautions may be different than what you will find online.

A quick search yields this MSDS which states that chloroform does have "carcinogenic effects" along with some other long-term, undesirable effects. As with any other MSDS it continues to go over best-practices and extremity limits.

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  • $\begingroup$ The mentioned Reddit post indeed has some useful info! Thanks for sharing MSDS and safety concerns, but that is not the information I am looking for. I asked about practical processing tips like exposure time, evaporation temperature and so on. I have higher education in chemistry and can handle chemicals safely, no worries :) $\endgroup$ – Klara Feb 23 '16 at 15:28
  • $\begingroup$ Sorry about that, I'd rather include the "no-brainer" type content for the poor sap that forgets something as important as the MSDS lol. I'll keep poking around, I found a few Google Group pages talking about it in my quick search. You might also try searching the forum pages on 3DHubs website. The peer-based printing service has some post-processing articles floating around. $\endgroup$ – tbm0115 Feb 23 '16 at 16:09
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Beside vaporizing with heat, you can use an atomizer and do cold vapor. The time is around 1-5 minutes at 45ºC for a 10x10x20 mm piece like a Marvin or a bot. I have done only gangster tests with it, so I have no larger piece info.

Passive vapor polish does not work with chloroform since it tends to crack. It needs a fast flash on the outside only.

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