Guides Post Production

[GUIDE] Painting 3D Printed Objects – Primer

Primer: how many times after we took an object off our beloved printer’s plate did we think it was missing something!? Often to give the final touch to our print just paint it, but let’s start with the background.
In this quick guide I will explain you how to prepare your print for painting.

Primer: Remove imperfections

Before painting, any filament residue or printing error should be removed.

Everything we need.
These residues, due to effects such as stringing or the use of poor quality filaments, can be easily removed by using two easy-to-find objects:
Both of these instruments must be used with caution. The lighter, in fact, is very useful for removing unwanted filament cobwebs or smaller lumps. How? With quick passages in the affected area so as not to heat up and, consequently, risk dissolving the piece (especially if you use PLA). With the knife, on the other hand, the hardest and most resistant residues can be removed from the surface. E.g. substrates that are too insistent.

Primer: Sanding the surface

This step is perhaps the most important to give a better look to your prints. The tools that can be used are different but I personally, after a little ‘experience, I opted for:
  1. Spray putty primer
  2. Sandpaper 
  3. abrasive sponges (those used by decorators).
Obviously this step requires patience especially if the object we are dealing with is very detailed or very small.
First of all you apply the spray putty spraying it on the object with alternating vertical and horizontal passes keeping the can at a distance of about 30 cm from the object.
Attention: the more you pass the primer, the more you run the risk of covering the small details.
Once the grout has dried, first sand it down with sandpaper soaked in water with a thick grain (usually 100).  And then, to scale, you use finer grains (first 150 or 180 and finally 220-240).
Personally, I also use sponges for details or in areas that are more difficult to reach.
This process can be repeated several times, alternating filler and sandpaper until you reach the desired result.

Cleaning and Primer

Once you have obtained the finish you want, remember to clean the object before proceeding with the next steps.
With paper or anti-dust cloths it is necessary to clean each point well to avoid dust deposits due to sanding, which could not stick the primer or even less the colors.
After cleaning thoroughly, it’s time to give the primer that will be essential to adhere to the colors we want to use, whatever they are. I recommend using a primer spray for plastic, specifically leaning towards a light gray primer but, depending on the colors that will be applied later, can also fit a white or black background. The primer is applied with the same procedure as the spray grout, taking care to completely cover the object.
If you want a superior finish I recommend the grey modeling primer by Tamiya, it costs a little more but it is definitely worth it.
Here we are! After waiting for the primer to be dry, here is your 3D printed object ready to be painted!

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