How to Use Acetone in Post-Processing: Vapor Smoothing FDM Parts

   By Tommy Dupuy on May 9, 2017

If you have an FDM 3D printer, you might have heard about vapor smoothing parts. For those who have not seen it yet, you’re in luck! Because in this blog we discuss how to use acetone in post-processing and use vapor smoothing on FDM parts.

What is Vapor Smoothing?

Smoothing is a 3D printing application finishing process that uses acetone or a solvent to finish parts after printing. This process is used to achieve a more polished finish (such as an injection molded look) and to seal your parts.

Why is This Finishing Technique Used on FDM Parts?

Naturally FDM parts are porous, so sealing them can be useful in several applications. Just to name a few:

  • Holding water
  • Holding air pressure
  • Sealing tools
    • Composite tooling
    • Sandcasting
    • RTV molding
  • Painting
  • Electroplating
  • And More

Now, not all FDM materials are compatible with the vapor smoothing process, but we can use ABS and ASA.

Using Acetone*

*Please note: We caution all users to know their risks when working with acetone or solvents.

While there are custom DIY solutions for making vapor smoothing chambers, if you find yourself doing this process a lot, it might make sense to look at a Finishing Touch Smoothing Station. DIY solutions are popular to explore, but they are not very consistent and can lead to a loss of time and money.

Another option for users who don’t want to use a chamber is to brush acetone or solvent directly on to your part. However, this process tends to be harder to control when applying due to uneven coats or over exposure. These application errors can give your part an appearance of melting.

To avoid the poor part quality mentioned above, I will show you why I recommend a Finishing Touch Smoothing Station and how easy it is to get that perfectly smooth part.

Testing How to Use Acetone in Post Processing

We started off 3D scanning a triceratops with an Artec scanner. After prepping the model in Artec Studio, we 3D printed several copies of the part for testing. In our tests, nine triceratops parts underwent different cooling times, smoothing times and smoothing repetitions to see how much exposure is necessary for that special finish.

We opened the station on the cooling side to prep the parts for the smoothing action. After about 15 to 20 minutes of cooling, we moved the part to the smoothing side. Here, we exposed each part to anywhere from 10 seconds to 1 minute of smoothing time. Then, we moved the part back to the cooling side to evaluate the finish. Note that the smoothing process is not immediate. You should allow for the part to rest. This is because the part is still cooking much like your food when it comes out of the oven. So, short cycles is recommended to get that perfect finish. We repeated the process until the desired finished was reached.

Here the results of a part that had no smoothing done, moderate smoothing (smoothed once for 30 seconds) and over-smoothing (smoothed twice for 1 minute the first time and 30 seconds the second time). All three parts experienced 15 minutes of cooling prior to vapor smoothing. 

FDM Part without Smoothing FDM Part with Regular Smoothing FDM Part with Over-Smoothing
Left: No Smoothing, Middle: Moderate Smoothing, Right: Over-Smoothing


Let’s take an even closer look at the fine details.

FDM Part without Smoothing FDM Part with Regular Smoothing FDM Part with Over-Smoothing
Left: No Smoothing, Middle: Moderate Smoothing, Right: Over-Smoothing


diy acetone vapor chamber
All three parts side-by-side going from most smoothed to least smoothed


For more post-processing techniques, watch our on-demand webinar called Post-Processing Your 3D Printed Parts.

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Tommy DuPuy

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