3D Tips for Out of the Machine Finishing FDM 3D Prints

Surface quality is a big issue in 3D printing. Whether you set your print to fine, medium or coarse settings, you know you have two options, time or surface quality.  A fine print setting can double or triple the print time but the surface quality of a coarse print is less than desirable so everyone has scratched their head and waited for a solution. Many tips and tricks have circulated around suggesting the use of an acetone vapor bath for FDM prints. There are many precautions needed for this process that make a product released from the company Smooth-On called  XTC-3D a product for 3D printing useful. XTC-3D is a brush on coating that fills in striations to seal the surface and provide a smooth surface that is a big leg up for 3D print quality.

We received the product to test before it hit the market last year and we applied our professional expertise to see if this product could compete with the acetone vapor bath method. Smooth-On is a company known for high-quality mold making and professional casting supplies and materials. Many of the products they offer can be great resources for post-production finishing of a 3D print or any other CNC related forms. 

Tips for Set-Up:

  • As always, review the Material Safety Data Sheets before using the product and thoroughly read the instructions provided with the product.
  • Mount or set up your 3D print in a work area where it can be left undisturbed while XTC–3D is curing.
  • Wear rubber or nitrile gloves.
  • Use the foam brush and measuring containers provided in the package.
3D printed cow head before coating is applied. 

3D printed cow head before coating is applied. 

Here’s What We Did:

1. 3D printed our model in ABS at .2mm layer height at a medium setting sized to 4" x 4"x 4".

2.   Mixed the 2 part solutions according to the product instructions (follow instructions closely).

3.     Brushing on solution with the provided foam brush is easy and goes on smoothly. It has a thick viscosity that auto-levels however you should make sure it does not pool in concave cavities.  Tip: Because of its exothermic properties you can extend it’s working time by pouring it into a shallow tray after mixing.

4.     Let solution cure on model undisturbed for 90 minutes. Around 90 minutes you will notice ridges smoothing. XTC – 3D does not melt detail like the acetone vapor bath.

5.     After 90 minutes, lightly and evenly sand with 220 to 320 grit sandpaper (go crazy with 600 grit if you like). Note: Only light sanding needed.

6.     Remix a new batch of XTC-3D and reapply to model. Tip: Second application really takes ridges down to a super smooth surface.

7.     Full cure time is 2 to 3.5 hours.

One of the reasons we took the time to run the tests with this product is that if you are intending to make a mold off of your 3D and use a plastic pour for faster reproduction of the sculpture/object, the smooth surface has a more appealing look and feel than the surface out of the FDM 3D printer. Bottom line too, this product is a safer solution to the acetone vapor bath, which for various reasons is best left to the dark ages of 3D printing.  

3D printed cow after applying the product.

3D printed cow after applying the product.

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