A professional painted finish on a 3D print comes from preparation: sand the surface, apply filler-primer to hide layer lines, sand again, then paint and clear-coat. Skipping prep is why most painted prints look rough. Done right, a printed part is indistinguishable from an injection-moulded product. Here is the step-by-step.
Key Takeaways
- Finish quality is 80% surface prep, 20% paint.
- Filler-primer fills layer lines; sand between coats.
- Light coats beat one heavy coat — avoid runs.
- Clear-coat protects and sets the sheen (matte/gloss).
- SLA needs less prep than FDM thanks to smoother surfaces.
The pro finishing steps
| Step | What to do |
|---|---|
| 1. Sand | Knock down layer lines (200→400 grit) |
| 2. Filler-prime | Fill remaining lines, reveal flaws |
| 3. Sand again | Smooth primer (600+ grit) |
| 4. Paint | Light coats, build colour |
| 5. Clear-coat | Protect + set sheen |
FDM vs SLA prep
FDM has visible layer lines that need sanding and filler-priming. SLA is far smoother and often needs only light sanding before primer — making it the better base for show-quality finishes. For big assemblies, bond first, then finish — see bonding & gluing.
Special effects
Metallic paints, soft-touch coatings, weathering, and two-tone masking all build on the same prep. A good base coat is what makes them read convincingly — essential for appearance models and props.
Let us finish it
Layer X offers professional finishing — sanding, priming, painting, and clear-coat — so parts arrive show-ready. Ask about finishing.
Frequently Asked Questions
Do I need primer?
Yes — filler-primer hides layer lines and helps paint adhere. It''s the single biggest quality step.
Which prints are easiest to finish?
SLA resin — smoother surface, less sanding. See finishing methods.