Saturday, March 30, 2013

3D Printing - Preparing the Raw Print for Painting

I wanted to share some model preparation steps, since this is very important in getting a great finished product.  The raw print from Shapeways is transparent, covered in a waxy like residue, and in some cases can look rather rough.  I did some research on the internet to see what people were doing to prep these models, and what type of paint to use.  The following photos illustrate what I am doing, but don't necessarily mean best practice.

First, I use a bath of Bestine brand heptane to soak the model overnight.  I then pull them out, rinse them with water, and let them dry.  Here is where I have seen some variance in my Shapeways orders.  It is obvious after observing the raw prints, that items can be printed using different orientation.  I shared this in an earlier post, and will show some examples.  Since each item is printed from the bottom up in layers, the supporting material used to hold the existing layers together during printing can leave a less than ideal surface.  It's not until the heptane has done its job removing the waxy residue that this becomes apparent.  Here is a great comparison of the two Pete cabs that were printed in the same batch.  One cab is nice and smooth, and the other will require some prep work:

What am I using to get the surface of the model smooth and ready for paint?  So far, I have found that a sanding needle works well for corners and cracks, and a medium sized micro brush will remove most of the flaky residue that is left after the heptane soak.

As far as the rest of the Petebilt parts, the frame turned out well.  I added some detail, but decided to not go overboard since this is N scale.  There are simulated airbags, springs, and shocks on each axle.  

The grill/bumper part, and the air cleaner canisters are a perfect fit, and only require some minor cleaning where they fit into the cab component.  These are exceptional prints, and show just how much detail can be obtained.

Here is an example of a grain trailer right out of the Shapeways box.  It is transparent, and has a thick waxy coat.  After a bath in heptane, it becomes white like styrene, and the details can be more easily seen.  I am sharing a photo of the tire/rim sets to illustrate this best.

Overall, I am pleased with Shapeways and 3d printing in general.  As you can see, it is not perfect, and models with differing results can be frustrating.  However, I am making the best of this newer technology, and hoping that it will continue to improve over time.  Unfortunately, the orientation of the model during printing is out of my control, and Shapeways will not accept requests for specific orientation at this time.  This is a shared concern by many designers based on public discussions I have observed online.  

I have a few models available for purchase through Shapeways now, and more to come in the future.  If you purchase one of my models, please let me know about your results.  My intent is to purchase and finish every model that I design before making it available publicly to ensure that it turns out as intended.


  1. Hi there,

    love the work! I'm currently printing up both HO and N Scale rollingstock and have also noticed the variation in results. Does the Heptane itself do anything to smooth out the print? OR is it just used to clean the surface of oil and wax?

  2. The solvent is just for removing the wax. It really does nothing to the surface of the model.