How to Paint 3D Prints — Primer, Paints & Finishing Techniques

A raw 3D print looks like a 3D print. A well-painted 3D print looks like a finished product — a prop from a movie, a piece of art, or a professional prototype. Painting is the single most impactful post-processing step you can apply to any print, and it is more accessible than most people think.

This guide covers the complete painting workflow from sanding through final clear coat. Whether you are finishing a cosplay helmet, a tabletop miniature, or a decorative piece for your shelf, these techniques will transform your prints.

The Complete Workflow Overview

1. Sanding — remove layer lines and surface imperfections
2. Cleaning — remove dust and oils
3. Priming — fill remaining lines and create a paint-ready surface
4. Primer sanding — smooth the primer for a flawless base
5. Base coating — apply your main color
6. Detail painting — add secondary colors and fine details
7. Washing and dry brushing — add depth and realism
8. Clear coating — protect the finish

You do not need to do every step for every project. A quick paint job might skip straight from priming to base coating. But following the full workflow produces professional results.

Step 1: Sanding

Sanding removes the visible layer lines that mark a print as 3D printed. As detailed in Anycubic's sanding guide, progressive sanding is the foundation of a good paint finish.

Sanding Progression

Start with coarser grits and work your way up:

• 120-150 grit — aggressive removal of support marks, blobs, and major layer lines. Only use this grit if the surface is very rough.
• 220 grit — the standard starting point for most PLA and PETG prints. Removes visible layer lines.
• 400 grit — smooths the surface left by 220 grit. After this stage, layer lines should be barely visible.
• 600-800 grit — fine sanding for a smooth surface ready for primer. Use wet sanding (dip the sandpaper in water periodically) for the best results.

Sanding Tips

• Sand in circular motions to avoid creating directional scratches
• Use sanding sponges for curved surfaces — they conform to the shape better than flat sandpaper
• Wet sanding at 400+ grit reduces dust and produces a smoother finish
• Do not skip grits. Jumping from 120 to 600 leaves deep scratches that finer grits cannot remove
• PLA sands easily. PETG is slightly tougher. Resin sands very smoothly.
• Wear a dust mask. PLA dust is not toxic but is irritating to breathe

What About Filler?

For deep layer lines or imperfections, spot-fill with automotive body filler (Bondo) or specialized 3D print filling compound before sanding. Apply, let cure, then sand flush. This adds time but produces a perfectly smooth surface.

Step 2: Cleaning

After sanding, your print is covered in fine dust that will ruin your primer adhesion if not removed.

• Rinse the print under warm water
• Use a soft brush (old toothbrush) to clean crevices
• Wipe down with isopropyl alcohol (IPA) to remove any oils from your hands
• Let dry completely — any moisture under primer causes adhesion problems

Step 3: Priming

Primer serves three critical functions: it fills remaining micro-imperfections, provides a uniform color base, and gives paint something to grip. According to Formlabs' painting guide, at least two coats of primer are recommended for the best results on 3D prints.

Best Primers for 3D Prints

Rust-Oleum 2X Ultra Cover Primer (spray) — ~$5-7/can The most popular choice for 3D prints. Available in gray, white, and black. The "2X" formula provides good coverage in fewer coats. Gray is the most versatile base for most paint colors.

Tamiya Surface Primer (spray) — ~$10-12/can A finer, thinner primer popular with miniature painters. Fills layer lines less aggressively but produces an extremely smooth surface. Available in gray, white, and pink.

Vallejo Surface Primer (brush/airbrush) — ~$10-15/bottle A water-based acrylic primer that can be brushed or airbrushed. Excellent for miniatures and small parts where spray cans are overkill. Thins with water and cleans up easily.

XTC-3D (epoxy coating) — ~$25 Not technically a primer, but a brushable epoxy that fills layer lines completely in one coat. Apply thinly, let it self-level, and cure for 2-4 hours. The result is a glass-smooth surface ready for painting. Best for large parts where sanding every layer line would take hours.

Spray Primer Application

• Hold the can 8-12 inches from the surface
• Apply in light, sweeping passes — not one thick coat
• Two to three thin coats with 10-15 minutes drying between coats
• Rotate the piece between coats to ensure full coverage
• Let the final coat dry for at least 1 hour before sanding

Brush Primer Application

• Thin the primer slightly (10-15% water for Vallejo)
• Apply in one direction, not back-and-forth strokes
• Two thin coats, drying between each
• Do not overwork partially dry primer — it will tear and leave texture

Step 4: Primer Sanding

This step is what separates good paint jobs from great ones.

After primer has fully cured, lightly sand with 800-1000 grit sandpaper. This smooths the primer's own texture, removes any dust nibs that landed during drying, and creates a perfectly smooth surface for paint. If any primer sands through to bare plastic, apply one more thin coat of primer to those spots.

As recommended in Raise3D's painting guide, this post-primer sanding step is essential for a professional finish.

Step 5: Base Coating

Now you apply your main color. You have three application methods, each with trade-offs.

Spray Paint

Best for: large parts, uniform coverage, smooth finish Brands: Rust-Oleum, Krylon, Montana Gold (artist-grade)

• Apply in multiple thin coats, not one thick coat
• 2-3 coats typically provides full coverage
• Rotate the piece between coats
• Spray paint provides the smoothest finish of the three methods

Brush Painting

Best for: small parts, multiple colors, detail work Brands: Citadel (Games Workshop), Vallejo, Army Painter

• Thin your paint. Consistency should be like milk, not yogurt
• Two thin coats are always better than one thick coat
• Paint in one direction to minimize brush strokes
• Use a quality brush — synthetic sable brushes (size 1-2) for details, flat brushes for large areas

Airbrush

Best for: professional results, gradients, large volume Equipment: Iwata, Badger, or Harder & Steenbeck airbrush ($50-200) + compressor ($80-150)

• Produces the smoothest, most professional finish
• Enables smooth gradients and fades impossible with brush or spray
• Requires more setup and cleanup
• Worth the investment if you paint frequently

Acrylic vs Enamel Paint

Acrylic paints are the go-to choice for most 3D printing applications. They are water-based, low-odor, dry quickly (10-30 minutes between coats), clean up with water, and are available in vast color ranges. Brands like Vallejo, Citadel, and Army Painter are formulated specifically for painting models.

Enamel paints (Testors, Humbrol) are solvent-based, producing a harder, more durable finish. They take longer to dry (2-4 hours between coats) and require mineral spirits for cleanup. Enamels are excellent for parts that will be handled frequently or need superior durability, but the fumes and cleanup make acrylics the better choice for most people.

Recommendation: Start with acrylics. They are easier to work with, safer, and produce excellent results. Consider enamels only for specialty applications requiring extreme durability.

Step 6: Detail Painting

Once your base coat is dry, add secondary colors and fine details:

• Mask with tape to create sharp color boundaries. Use Tamiya masking tape for curves — it conforms better than standard painter's tape.
• Paint details by hand with a fine brush (size 0 or 00). Brace your painting hand on your holding hand for stability.
• Work dark to light. It is easier to paint light colors over dark than the reverse.
• Clean mistakes immediately with a damp cotton swab while the paint is still wet.

Step 7: Washing and Dry Brushing

These techniques add depth and realism that flat colors cannot achieve.

Wash (Shade)

A wash is very thin, dark paint (or premixed products like Citadel Nuln Oil or Army Painter Dark Tone) that flows into recesses and crevices, creating shadows. Apply it liberally over the model and let it settle into the low points. Wipe excess from flat surfaces with a clean brush or cloth. This single technique dramatically improves the appearance of any painted model.

Dry Brushing

Dry brushing highlights raised surfaces. Dip a wide, flat brush into a lighter shade of your base color, then wipe most of the paint off on a paper towel until almost nothing comes off. Lightly flick the brush across the model's surface — paint will catch only on edges and raised details, creating natural-looking highlights.

Weathering

For a battle-worn or aged look:

• Chipping: Dab a small sponge with a dark metallic color (like gunmetal) on edges and corners
• Rust: Apply orange-brown washes to recesses, then stipple with a sponge
• Dirt and grime: Dry brush with dark brown or earth tones on lower surfaces
• Scratches: Use a fine brush with silver or light gray to paint thin scratches along edges

Step 8: Clear Coating

A clear coat protects your paint job from handling, UV damage, and wear.

Matte vs Satin vs Gloss

• Matte — no shine, gives a natural, realistic appearance. Best for miniatures, terrain, and props meant to look real.
• Satin — subtle sheen, a versatile middle ground
• Gloss — high shine, best for metallic finishes, wet surfaces, or a polished look

You can use different finishes on the same model. Gloss on metallic armor, matte on cloth and skin, satin on leather.

Application

• Spray clear coat in the same thin, sweeping passes as primer
• Apply 2-3 coats for durable protection
• Let cure fully (24 hours for handling) before using the piece
• Krylon Matte Finish and Rust-Oleum Matte Clear are popular, affordable choices
• Vallejo Matte Varnish works well for brush application on miniatures

Material-Specific Tips

PLA

• Sands easily and takes paint well
• No special preparation beyond sanding and priming
• Avoid heat guns or hair dryers for drying — PLA softens at 60°C

PETG

• Slightly harder to sand (material is tougher)
• Adhesion is excellent once primed
• Can handle slightly more heat during drying

Resin

• Sands very smoothly due to lack of layer lines in XY plane
• Wash and cure completely before painting
• IPA wipe is essential to remove residual resin before primer
• Resin holds detail exceptionally well, making it ideal for miniatures

Find Models Worth Painting

The best models for learning to paint are designed with clear surface details — raised edges, recesses, and distinct areas for different colors. Search for miniatures, busts, and cosplay props on 3DSearch to find models specifically designed for painting. Many model creators include painting guides with their designs.

Final Thoughts

Painting 3D prints is a skill that improves with practice. Your first paint job will not be perfect, and that is fine. Each project teaches you something — how thin to mix paint, how much primer is enough, how to steady your hand for detail work. Start with a simple piece, follow this workflow, and you will be surprised how quickly your results improve.