How to Dissolve PLA and Smooth It: Chemicals to Use

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If you have PLA stuck on your print bed or nozzle, or you just want to smooth your PLA prints a little and remove layer lines, you’re probably looking for a way to dissolve PLA filament or smoothen it.

In this post, we’ll look at the various methods you can use to dissolve PLA and see how effective or safe they are.

The best way to dissolve PLA is to use ethyl acetate, which is the main ingredient in non-acetone nail polish removers. However, ethyl acetate is a carcinogen and should not be used without proper care. Acetone does not dissolve PLA very well and you’ll get mixed results at best.

levels of smoothness in 3D prints

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Dissolving PLA with ethyl acetate

Ethyl acetate is the most effective way to dissolve PLA. It easily breaks PLA down. Ethyl acetate also evaporates very quickly, so once you use it, it will quickly dissipate into the air.

Whenever you handle any sort of chemicals, remember to do so in a well-ventilated area so you don’t unnecessarily breathe in any fumes.

Ethyl acetate is not toxic but it is a potential carcinogen and it is absorbed into your skin very easily.

If you don’t want to fully dissolve PLA, you can use very small amounts of ethyl acetate to smooth your PLA prints, too, much like how ABS prints are smoothed with acetone.

Dissolving PLA with acetone

Acetone is not very effective at dissolving PLA. Pure PLA will not react with acetone, but if there are some impurities, you may see some results. Still, it’s not as effective as ethyl acetate and acetone is best used to dissolve ABS.

Again, safety first! Do not try this in a poorly ventilated area!

Dissolving PLA with caustic soda

Caustic soda or sodium hydroxide also works well to dissolve PLA, but it is highly basic and should be handled with extreme care. One way you can dissolve PLA with caustic soda is by adding caustic soda to water to make an alkaline solution and soaking the PLA part in the solution.

With a little bit of time, the lactic acid will saponify and you can just pour the solution down the drain.

The highly basic nature of caustic soda means it is corrosive, so you should handle it with extreme care. DO NOT use caustic soda at home! Make sure you have the proper safety equipment.

Dissolving PLA with methylamine

Methylamine(which you probably know from Breaking Bad) in water can also dissolve PLA. Methylamine gives off fumes that can irritate your eyes and lungs, and you should not use it at home unless you have the proper equipment like a fume hood.

A mixture of methylamine and water can dissolve PLA.

Dissolving PLA with dicholoromethane

Dichloromethane is a chemical which is the primary ingredient in some types of paint stripper. It’s not very easy to find(you can’t just order some from Amazon!), but if you are able to source it, it will work well with PLA and PLA+.

Dicholoromethane can also be used to weld PLA parts together. A small amount will make the plastic sticky, and you can join two parts together. Once the plastic reforms, you’ll have a fairly strong bond between both parts.

Dissolving PLA with isopropyl alcohol

PLA generally does not dissolve in isopropyl alcohol, but Polymaker PLA does when used with Polymaker’s proprietary smoothing device.

This device is called the Polysher and it spins your Polymaker PLA parts in a mist of water and 90% isopropyl alcohol to smooth the surfaces of your print.

Smoothing and dissolving is essentially the same thing, except dissolving is going one step further!

If you don’t want to invest in a smoothing machine, you can also just spray Polymaker PLA parts with a mist of water and 90% isopropyl alcohol. You won’t get quite the same results, but it will work for basic smoothing.

The Polysher is not cheap(it costs more than a budget 3D printer), but if you’re looking for something that works with PLA and is not highly toxic, it is worth a shot:

Polymaker Polysher - Post Processing Device to Smooth Print Surface with IPA Alcohol for PolySmooth PVB 3D Printer Filament & PolyCast 3D Printing Filament

  • Post-Processing Machine : Polymaker Polysher is a post-processing machine designed for polishing the extrusion-based FDM/FFF 3D printed parts with PolySmooth to achieve a shining, layer-free surface finish.

  • Safe & Easy To Use: No heating is involved – The nebulizer technology requires only a very small reservoir – It is a liquid-phase polishing rather than vapor-phase polishing process. All electronic components are properly sealed, and no spark can be generated inside the chamber. Placing it on your desk, simply twisting the dial to set the time, the post-process will start and end automatically.

  • Low Costs: The Polysher is not only affordable but its running cost is incredibly low too. Isopropyl alcohol (also known as isopropanol) or Ethanol are both suitable. You can choose whatever is more easily available for you.

  • NOT A 3D Printer: the Polysher is NOT a 3D printer. You still need a extrusion-based, FDM/FFF 3D printer in order to use our new products. Specifically, PolySmooth is a new filament that you can print with your 3D printer, just like how you print with your PLA. Once the printing is done, you can post-process your printed objects in the Polysher to obtain the amazing surface finish. You can watch our Polysher video on YouTube.

Of course, you’d have to stick to only using Polymaker filament. Polymaker filament costs around twice as much as regular filament.

Again, you’ll have to consider whether smoothing PLA is very important for your use case.

Dissolving PLA support material

One of the most common reasons for wanting to dissolve PLA is to dissolve support material. When you break off support material, the breaks are not always very clean and a little bit of material is left stuck to the 3D print.

Also, if your settings are not configured very well, you may find that the layers right above the support are not formed very well and the layer lines are much more visible than they would be elsewhere.

In this case, dissolving the support material would give you the cleanest finish.

You have two ways to do this:

3D Print the supports in PLA and the model in another

This will give you the cleanest possible finish, since you’re chemically ensuring that the other material will not dissolve. For your main material, choose something like PETG, Nylon, or HIPS, and print the supports in PLA.

Please note that printing supports in one material and the model in another requires advanced slicing!

Then just soak the entire part in a solution that dissolves PLA(like ethyl acetate) and that will completely dissolve the supports.

Break off the supports manually and dissolve the residue

If you’re unable to print in two materials, then you can just 3D print the entire model in PLA and manually break off the supports as you normally would.

Then, if there is any material left over, you can dissolve it using one of the methods we listed above.

Smoothing PLA

Even though we’ve mostly talked about dissolving PLA so far, you can certainly use the same methods to just smooth PLA as well, like you saw with the Polysher device.

Dissolving is just smoothing gone too far!

Smoothing is great for giving a really nice, glassy finish to your 3D prints which you can just not get with a FDM printer. For really smooth prints out of the box, you’d need to use a SLA printer, and those are completely different ballgames.

Conclusion

PLA is not an ideal material to use if you want to dissolve or smooth it, but if the need arises, the chemicals we’ve listed above can do the trick.

The safest way to do it is using isopropyl alcohol, as it’s a common household chemical and not as much of an irritant as the other more volatile chemicals listed here.

Finally, if you don’t want anything to do with chemicals, you can try smoothing or melting your prints using a hair dryer or heat gun, but you do risk deforming the 3D print if you apply too much heat or heat unevenly.

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