Smooth 3D Prints using a Cold Acetone Vapor Bath

3D Printing is very handy, but often the resulting prints have ridges which are neither visually, or functionally ideal. I’ll show you how you can use Acetone to smooth ABS plastic into a nice, glossy finish.

Why would I want to do this?

It’ll reduce the ridges on 3D printed objects, leaving them with a shiner surface. It’ll help the layers bond together, increasing the strength of a part. It’ll help close any small cracks, defects and pockets left by the 3D printing process, decreasing crevasses that bacteria could grow in for parts in contact with food or the body.

Why Acetone, and why ABS?

First, this technique only works on prints using ABS, not other types of common plastics like PLA. Acetone dissolves away ABS, and we will use this property to dissolve away the ridges of our prints. If we subject our print to an acetone vapor rich environment, the vapor will condense onto the plastic. After we give it some time to eat away some of the ridges, we’ll remove the print and let the acetone evaporate off the print. We are then left with a strong, smooth object.


  • Pure Acetone – Acetone mixtures such as nail polish remover won’t work, we need pure acetone. You can buy it at most home-improvement retailers.
  • Empty Paint Can – Make sure the can is metal, and large enough to cover the object you want to smooth with plenty of room on the sides.
  • Paper Towels – Used to line the paint can, and soak up the acetone.
  • Magnets – Used to hold the paper towels to the sides of the paint can (see, the metal can is helpful!). A handful of strong magnets from the hardware store will work.

The Setup

The set up is simple. Take the paper towels and line the inside of the paint can with it. You want to make sure the sides and bottom are completely covered. Use the magnets to secure the paper towels. You want to make sure that none of the paper towels will actually be touching the object you want to smooth (it’s called acetone vapor bath, not acetone-soaked towel smothering).

Bath Time

With the lid to the can upside-down, place your object in the center of the lid. As a sanity check, double check that you can cover the object with the paper-towel lined can without touching it. We are ready to begin. Pour enough acetone onto the paper towels to make them consistently damp, but not enough to pool in the bottom or drip. Cover the object, and let it do its magic. Aim for about 40 to 60 minutes. Larger parts will require more time, but be careful, smaller details can be dissolved away if left in too long. You may have to experiment with time to adjust for paint case size, amount of acetone, size and quality of the print. Once you’ve checked that the print had achieved the look you desire, remove the can.

Let It Dry

Your print will need an hour (or maybe longer!) to let the remaining acetone evaporate away. You’ll find that the surface is very gummy right now, and if you try to move the object, it’ll simply bend and be mushy, leaving fingerprints and imperfections on the surface. Give it time to dry, and you’ll soon find that your object is much stronger, and shiner than before! Congrats, you just completed your first Cold Acetone Vapor Bath!

I hope this post helped guide you on performing your own Cold Acetone Vapor bath. I would love to see your results, and as always, let me know if you have any questions in the comments below!
-Christopher Hoffman

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