Fresh off the printer, most 3D prints have visible layer lines, support marks, and a rough texture. Post-processing closes that gap between "printed part" and "finished product."
This guide covers everything from basic sanding to smooth, painted results you'd struggle to identify as 3D printed.
Before any finishing, clean the print thoroughly.
Use flush cutters or needle-nose pliers to remove support structures. Work slowly near the model surface to avoid gouging.
Tips:
Sanding removes layer lines and creates a smooth surface for painting or display.
Start coarse, finish fine. For heavily layered prints:
Wet sanding (800 grit and above) produces a much better result than dry sanding alone — the water flushes away plastic dust and reduces heat buildup.
Sanding alone won't fix large layer gaps, cracks, or deep support marks.
Filler primer spray fills minor imperfections in one coat. Apply a thin coat, let dry, sand with 400 grit, repeat. 2-3 coats of filler primer + sanding produces a very smooth base.
For larger gaps, automotive spot putty fills deep marks. Apply with a spatula, sand once dry. Works well on flat and curved surfaces.
XTC-3D is a two-part epoxy coating designed for 3D prints. Brush it on and it self-levels, filling layer lines and creating a hard, smooth surface. Probably the most effective single product for a smooth finish without heavy sanding.
If you printed in ABS, acetone vapour smoothing produces a near-injection-moulded finish with almost no manual work.
Safety: Do this outdoors or in a very well-ventilated area. Acetone is flammable — no open flames, no sparks.
Result: Layer lines disappear, surface becomes glossy and smooth.
Important: This only works on ABS. Acetone has no effect on PLA or PETG.
Never paint directly onto bare plastic. Primer:
Use plastic primer spray in light, even coats from 20-30cm away. Let each coat dry fully before adding the next. Two coats is usually enough.
Grey primer is easiest to paint over. White primer is better under light colours.
Spray paint gives the most even finish on 3D prints. Rustoleum and Montana are popular choices.
Technique:
For detailed miniatures, props, or multi-colour pieces, acrylic paints applied with a brush give full control.
Thin your acrylics slightly with water for smoother coverage. Multiple thin layers always beats one thick one.
An airbrush kit produces the smoothest hand-applied finish possible, and is worth it if you paint regularly. Steep learning curve, but the results are excellent.
Always seal your finished paint job with a clear coat to protect it:
Rustoleum clear coat spray works well for most applications. Two light coats is enough.
| Method | Effort | Result |
|---|---|---|
| Light sanding + primer + paint | Low | Good |
| Full sand (to 2000) + filler primer + paint | Medium | Very good |
| XTC-3D coating + paint | Medium | Excellent |
| Acetone smooth (ABS only) + paint | Medium | Near-perfect |
| Full sand + filler + primer + airbrush + clear coat | High | Professional |
For most prints, the process is: remove supports - sand to 400 grit - filler primer - sand to 800 - paint - clear coat. That's achievable in an afternoon and produces results that look nothing like raw 3D prints.
If you want the smoothest possible finish without lots of sanding, XTC-3D epoxy coating or acetone smoothing (for ABS) are the fastest routes to a near-perfect surface.