Smoothing 3d Print PLA With 1,3-dioxolane

2,348

27

6

Introduction: Smoothing 3d Print PLA With 1,3-dioxolane

About: Hi, I'm Matthieu Sonnati. I started my career as a Material Scientist and I'm now an entrepreneur in EdTech, helping others to find their way and learn new skills. My hobbies are related to making things ;) F…

The best solvent to smooth PLA is 1,3-dioxolane.

At least according to my calculations 😅 (yeah I'm kind of a chemist who loves math).

Anyway, I won't give you a lesson about why 1,3-dioxolane is the best solvent for PLA. You can go check this wikipedia page to know more about this solvent.

What you should know is:

  • 1,3- dioxolane is commonly used in paint solvent formulation and dissolve a lot of polymers/plastics,
  • This solvent is very good at dissolving many organic compounds and our body being mainly organic 🤪 it's not suprising that this solvent can be harmful for your health. However, it is less harmfull (not CMR) than other solvents described in literature to smooth PLA such as THF or Chloroform. And thus, it deserves more attention.

There are many articles/tutorials written out there about post-processing techniques for 3d printed objects in PLA, but most of them do not highlight how good 1,3-dioxolane is to smooth PLA:

  • 1,3-dioxolane is mentioned in a peer-reviewed article by Sato, S., Gondo, D., Wada, T., Kanehashi, S. and Nagai, K. (2013), Effects of various liquid organic solvents on solvent‐induced crystallization of amorphous poly(lactic acid) film. J. Appl. Polym. Sci., 129: 1607-1617. doi:10.1002/app.38833. However their conclusion is quite limited (quote: "PLA films are soluble in polar aprotic solvents") and fail to highlight why 1,3-dioxolane is particularly a good fit with PLA.
  • BrittLiv has written a very detailled 12-steps tutorial on instructables that I highly recommend you to read. It's well explained and she mentions also safety concerns which are critical when handling solvents, even for those with moderate toxicity. However, she didn't investigate 1,3-dioxolane for smoothing PLA, probably because this solvent is not easily available commercially. In this article I'll give you a few tricks on how to get this solvent.

Safety

Before I continue, I want to take the time to discuss about the safety concerns associated to handling solvent and especially 1,3-dioxolane.

According to its MSDS, 1,3-dioxolane causes serious eye irritation (H319) meaning you have to wear protective glasses and use it in well ventilated area.

Also, it is highly flammable liquid and vapour (H225) meaning you have to handle it away from any flame or ignition source and again in a well ventilated area.

So please protect yourself, wear your Personal protective equipment (PPE): glove, glasses and mask (you should get used to it with the covid19 situation around here ;)

Note: do not mistake 1,3-dioxolane with 1,4-dioxane. The names may be close, those are two very different chemical compounds with different polarity and toxicity!

Supplies

How to get 1,3-dioxolane?

I'm familiar with two producers of 1,3-dioxolane:

  • BASF is a global producer of chemicals and this solvent is part of their Intermediates division.
  • Lambiotte is a producer of chemicals, mainly from the acetal chemical family. They are located in Belgium.

If you are a company and are authorized in your country to buy/handle/sell chemicals so you can probably contact these companies or their local dictributors to buy 1,3-dioxolane in bulk.

If not, you can look at product such as paint strippers. I hope by sharing this info with the community that we can identfy more products containing 1,3-dioxolane.

The only commercialy available product I found containing 1,3-dioxolane is the Paint Stripper spray can from Montana. They do not advertise this product as being able to smooth PLA but as a general purpose paint stripper for graffity or DIY.

As you may know from my other articles on my blog, I'm a big fan of Montana paint spray cans for painting miniature scenery and terrain. That's how I found out this product and I was quite happy to discover in the MSDS of this product that it contains 30-40 % of 1,3-dioxolane among other solvents. That's not as good as pure 1,3-dioxolane but still I immediately thought it might do the trick (and it did as you will see below).

For my friends in France, you can buy this product on Allcity website.

For my friends around the world, I don't know. Let me know in the comments if you find this product (or other similar products containing 1,3-dioxolane) in your country and I will update the list

Step 1: Smoothing With Montana Paint Stripper Spray

Here is a quick experiment I did using Montana paint stripper spray. For those following me on IG or on my blog, I'm currently working on a Kessel game board for Star Wars legion and I needed some pipe connectors. I 3d printed a dozen "Industrial pipe components for Warhammer40k" by ComradeQuiche available here on Thingiverse and used it as a test for this experiment. This model has a curved shape that makes it hard to sand and was thus a good way to see how this paint stripper could affect the surface.

In term of 3d printing settings, I used an Alfawise U20 with 0.4 mm nozzle, 100 micron z layer resolution and Sunlu PLA+ filament.

  1. I sprayed three layers of Paint stripper waiting a few minutes between each
  2. I covered the piece with a glass to slow dow solvent evaporation
  3. As you can see on the picture, on the piece after drying, the surface change to white due to partial solvent‐induced crystallization as described in literature
  4. To better compare I applied a layer of brown spray paint
  5. As you ca see on the pciture, on the left: untreated, on the right: treated with paint stripper

As you can see it's far from being perfect but it definitely has an effect on the piece and I'm pretty sure with a more dedicated formulation we could have product specifically designed for 3d printed PLA object smoothing using 1,3 dioxolane.

Step 2: Smoothing With Pure 1,3-dioxolane

I tried to use pure 1,3-dioxolane on another piece of the same model. In this experiment I simply dipped the piece in pure 1,3-dioxolane for 1 min.

Please note that when handling this solvent you need to use glassware and/or stainless steel only as it will dissolve most plastics. Pay attention if you want to use a brush as it can also dissolve most synthetic hair.

  1. I poored pure 1,3-dioxolane in a glass cup
  2. I dipped the piece for 1 min
  3. The surface is way smoother, layer separation is less visible
  4. To better compare I applied a layer of brown spray paint
  5. Left: untreated, right: treated with 1 min in pure 1,3-dioxolane

Step 3: Smoothing With Mixture of 1,3-dioxolane + 7% PLA

Last experiment was to use a mixture of 1,3-dioxolane with 7 wt. % of PLA. I used misprints that I cut in small chunks and let it dissolve in 1,3-dioxolane overnight. Due to the molecular weight distribution of PLA, the solubility is partial so you need to shake it before use.

This time I only did a quick 10 s dip of the piece in the mixture, then let it dry.

  1. Quick dip of the piece for 10s (time to take the picure)
  2. Left: untreated, right: treated with 10 s in mixture 1,3-dioxolane + 7 wt. % PLA
  3. To better compare I applied a layer of brown spray paint
  4. While not as smooth than 1min dip in pure 1,3-dioxolane, the result is quite promising

Step 4: Next Steps?

As you can see with these three experiments, it's far from being perfect and it's more exploratory than anything else.

My objective with this tutorial is to share this info with the community to open new possibilities together. I'm sure we can develop product that are better adapted for post-processing 3d printed PLA objects. Imagine if we could have access to a whole range of paints specially formulated with 1,3-dioxolane. This would open up a wide range of application I'm sure in the 3d printing world.

So let me know what you think in the comment. I hope this could inspire others in the Maker community to investigate more this path and maybe together we can developped better PLA post-processing techniques than the few products we have at our disposal now.

Take care and happy (safe) making ^^

Matt Sonnati (SimpleAsWar)

3D Printed Contest

Participated in the
3D Printed Contest

Be the First to Share

    Recommendations

    • Maps Challenge

      Maps Challenge
    • Summer Fun: Student Design Challenge

      Summer Fun: Student Design Challenge
    • Make it Fly Challenge

      Make it Fly Challenge

    6 Comments

    0
    NeilRG
    NeilRG

    1 year ago

    Your knowledge is impressive, and the presentation very detailed. Fine tuning my printers yields excellent results. The chemical solution presented has toxicity and flammability issues I will refrain from using.

    0
    Icelandian
    Icelandian

    Question 1 year ago

    Hey Matt, question for you. I know this Instructable focuses on FDM printing, but was wondering what your thoughts would be if it were used to clean the uncured liquid resin from SLA printed parts. If not, would you happen to have any recommendations for alternatives to the standard IPA everyone uses, since IPA is not available now? I've tried a few suggestions from our good friend Google but none work as well as a good soak in IPA. (Mean Green kinda works. Even bought a jug of cheap Vodka and it made them worse!)

    0
    Matt-S
    Matt-S

    Answer 1 year ago

    Hi,

    Liquid resin used for SLA 3d printing can have a wide range of composition. From what I could gather by looking at a few MSDS of the major brands they are mostly based on acrylate prepolymers with photonitiator which activates polymerization ("curing") when exposed to light (UV). Sometimes, use of urethane prepolymers is also described. All the prepolymers (resin) and the resulting polymers after curing/printig (printed part) should be sensitive to polar aprotic solvant such as 1,3-dioxolane as decribed by BASF in their technical datasheet (http://www.intermediates.basf.com/chemicals/web/en...

    So it should work but be carefull because it will be much more powerfull than IPA at dissolving uncured resin and your printed part too.
    1,3-dioxolane being highly soluble in water, maybe you could mix it with water to control its dissolving power on your printed part.

    Also, have you tried acetone? It may work for your need and it is much easier to find acetone in a local DIY store than 1,3-dioxolane.
    Hope this helps

    0
    Icelandian
    Icelandian

    Reply 1 year ago

    Cool, thanks for the detailed answer. Actually had some acetone in the garage (not sure why I had it, but glad I did). I tried it on a part that just finished and it worked way better that what I've tried so far. (Still not as good as IPA though.) My next thought was going to be to try denatured alcohol as I'm pretty sure I saw that on the shelves of our local hardware store. But I'll stick with the acetone I have for now. Thanks for the suggestion!

    I like the idea of using this but after dilution. I'll report back any findings if I do.

    0
    Matt-S
    Matt-S

    1 year ago

    Thanks for your feedback.

    Settings optimization is definitely critical to get good prints. However, the objective here is experimental, not qualitative. Through these experiments I wanted to explore an alternative post-processing technique and share it with the community. The piece being "very rough" was thus on purpose as it helps to highlight the effect of 1,3-dioxolane on PLA prints. My hypothesis was: if it works ok on a PLA prints with highly visible layer separation, it would work even better on PLA prints with less visible layer separation.

    I would be very interested to see how good you could print this model and the settings you used. It is available here on thingiverse: https://www.thingiverse.com/thing:1810675
    It was printed at 38% scale. Please let me know your findings.

    0
    lime3D
    lime3D

    Tip 1 year ago

    You can greatly reduce the need for smoothing by adjusting the settings of your 3D printer. In your photos, the part looks VERY rough and uneven. Try some sort of Z brace to prevent shaking and movement, reduce the speed and layer thickness. Your parts shouldn't look that bad to start with. This is a PLA part from my $250 printer, with no post print finishing.

    DSCF4811.JPG