Spray Painting your 3D Prints

This was my first botched attempt at spray painting my 3D prints, and there will be many more that follow.

I'm using PLA as the print medium, and some cheap spray from the hardware store.

I’m using PLA as the print medium, and some cheap spray from the hardware store.

 

Here’s what you need:

  • Primer
  • Spray paint
  • Clear coat
  • Masking tape
  • Sand paper
  • Exacto knife (for applying and removing masking tape
  • Wires, strings, boxes, or other disposable things to suspend your print or paint on

 

What I actually  used:

  • 1 can Rustoleum Satin (olive green spray paint)
  • 1 can Krylon Matte Finish (clear coat)
  • Blue painter’s tape

Total cost: $3

 

Step 1: Always calibrate your printer.

The overall quality and resolution of your print makes a huge difference, so take some time to calibrate your printer. Spray painting won’t hide any flaws in your print. I decided to run my tests on less-than-perfect prints, and you can clearly see all the flaws in the pictures below. I would recommend that everyone practices on their bad prints before attempting to spray their better quality prints.

Step 2: Clean your print before painting.

You can lightly sand your prints before spraying, but this can be a double-edged sword. PLA doesn’t respond particularly well to sanding, so proceed with caution (else you might just gum up the print even more). Work you’re way from a rough grit sandpaper to a fine grit sand paper. I would recommend starting with something like 80-100 grit and ending at about 300-500 grit. Take your time.

I opted to skip the sanding in this trial because I want to see how well the paint adheres to a “fresh print” with no post-processing. Some paints like Krylon Fusion and Plastidip might not need much prep work (or so I’ve heard).

Step 3: Mask your print.

Mask off anything you don’t want to be painted. A good masking job will give you clean, professional edges when you remove the tape.

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Step 4: Spray with many light, even coats.

The key to a good-looking rattle-can job is to use many light coats of paint.  Shake the can well before you start spraying and always test spray before you start. When spraying, sweep the paint across the print using long, overlapping coats. Start spraying off to one side of the print, and end your coat off the other side of the print.

Use 5-10 light coats of paint plus several light coats of primer to seal it up. Thin coats of paint help with adhesion; if the coats are too thick/heavy, the paint will look gummy and peel off easily.

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Step 5: Let it dry before you peel the masking tape.

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As always, safety comes first. Always spray in a well-ventilated area and use a respirator. The fumes are strong and dangerous.

Tips, Tricks, and Other Resources

  • Painting is 80% prep work. Take extra time cleaning and masking your print for a good looking spray job.
  • Regular Rustoleum spray paint works okay; Krylon Fusion probably works a little better because it’s designed for painting plastics.
  • Plastidip might be another good choice for painting your prints, but I haven’t experimented with it yet.
  • Krylon How-To / FAQ
  • Krylon Best Practices
  • Popular Mechanics Spray Painting Tips

 

Not perfect, but not bad for a $3 color change.

Not perfect, but not bad for a $3 color change.

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