Workshop Post-Processing for 3D Sculptures: Sanding, Filler Primers and Dry Brushing
A complete step-by-step guide from raw FDM/SLA print to collector-grade sculpture: scar-free support removal, wet sanding progressions, filler primers and acrylic washes.
A complete step-by-step guide from raw FDM/SLA print to collector-grade sculpture: scar-free support removal, wet sanding progressions, spray fillers and acrylic washes.
A clean 3D print is only half the job. The real craftsmanship behind collectible sculptures, busts and dioramas comes from careful post-processing and multi-layer painting.
In our Dortmund workshop, we have refined a repeatable finishing process (from Outlast-inspired figures to monumental Balrog and Baphomet sculptures) that completely hides FDM layer lines and brings out realistic depth of detail.
⚡ Key takeaways:
- 🌡️ Warm-water bath: softening supports in water at around 50°C lets you remove them without tearing chunks out of the model.
- 🛠️ Wet sanding: a 240 → 400 → 800 grit progression combined with a filler primer creates a perfectly smooth base.
- 🎨 Acrylic shading: combining a zenithal prime, a dark wash and dry brushing brings out the finest anatomical and surface details.
1. Scar-free support removal and warm-water bath
Instead of snapping supports off dry with pliers, which often tears out parts of the model:
- 🧪 Resin prints (SLA): remove supports before the final UV cure. Soak the model for 3 minutes in warm water (approx. 48–52°C) — the support contact points soften and come away cleanly, leaving no marks on the surface.
- ⚙️ FDM prints (PETG/ASA): use a hobby scalpel with a No. 11 blade and a rotary tool with a diamond burr, slowed down to 3,500 RPM to keep the plastic from melting.
Raw UV resin print prepared for a warm-water bath and support removal
2. Wet sanding progression and filler primer
Choosing the right sandpaper and grit sequence determines how smooth the surface will be:
| Stage | Grit | Medium | Goal |
|---|---|---|---|
| 1. Leveling | 240 (wet) | Water with a drop of dish soap | Sanding off support marks |
| 2. Filler primer | — | Tamiya Surface Primer / Motip Filler | Filling micro-gaps between layers |
| 3. Smoothing | 400 → 800 (wet) | Demineralized water | A satin base ready for paint |
| 4. Final polish | 1200–1500 (optional) | Fine polishing compound | Mirror-smooth armor plates |
Workbench with the finished, richly textured Baphomet altar sculpture
3. Zenithal priming and dry brushing
- 🎨 Zenithal highlighting: with a 0.3 mm airbrush, apply a matte black primer from below, then a light mist of white from above at a 45° angle. This creates a natural map of light and shadow.
- 🖌️ Acrylic wash (shading): thin paint with reduced surface tension flows into recesses, fabric folds and rock cracks, instantly emphasizing the sculpture’s anatomy.
- ✨ Dry brushing: a flat natural-bristle brush with a tiny amount of thick acrylic paint (wiped off on paper) lightly grazes the most raised edges, simulating worn metal, bone or skin texture.
Artistic dry-brush finish on the Asylum Ghouls collectible sculpture
4. Protecting the finish with ultra-matte varnish
The final step is to seal the paint with two thin coats of UV-resistant ultra-matte acrylic varnish. It removes unnatural plastic shine and protects the sculpture from sunlight.
You can view and order all our finished sculptures directly in our 3D Works Gallery.