Short answer: OSL means painting light as if it comes from an object on the model: pick the light source, then tint every surface facing it with the light colour — strongest at the nearest point, fading with distance. Two glazes and one highlight colour are enough for a convincing effect. Reflection, not brightness, is the secret.
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What Is OSL — and Why It Elevates Your Models
Object Source Lighting is the painted illusion that a model emits light: a torch, a plasma coil, a warp portal. Done well, OSL makes viewers see light instead of paint. It’s the single highest-impact technique in the hobby — and it’s less about skill than about discipline: consistent light direction, controlled intensity, restrained coverage.
Step 1: Determine Light Direction and Falloff
Fix three things before painting:
- Where the light source sits on the model
- Which surfaces face it — mentally trace a straight line from the source to every panel
- How far the light reaches — falloff is fast; light rarely travels more than 10–15 mm convincingly
Mark the facing surfaces with a light pencil dot if you need to. OSL fails when light lands on surfaces that couldn’t possibly see the source.
Step 2: Layering Transparent Glazes
- Mix your glow colour as a thin transparent glaze (glaze medium or heavily thinned paint)
- Apply 1 glaze to the outermost zone of the lit area
- Apply 2–3 glazes on the mid zone
- Apply 4–6 glazes — or a stronger mix — on surfaces immediately adjacent to the source
Because glazes are transparent, the underlying paint still reads through: this is what makes OSL look like light on a surface rather than paint on top of it.
Step 3: The Source Itself
Paint the emitting object at maximum brightness: base colour → bright tone → near-white core. The source must always be the brightest point of the model, or the whole illusion collapses.
Step 4: Avoiding Common Over-Glowing Mistakes
- The “spray tan” error — tinting every surface equally. Light has direction; distance matters
- Too saturated colour — real light washes surfaces out; your glazes should lighten, not just colour
- Light on impossible surfaces — the underside of an arm facing away from the torch breaks the illusion instantly
- Glow stronger than the source — reflected light is always dimmer than the emitter
When to Use Which Effect
| Effect | Best tool | Difficulty |
|---|---|---|
| Small glow (eyes, coils) | Direct painting (see glow guide) | Beginner |
| Medium OSL (torch, weapon) | Glazes on facing surfaces | Intermediate |
| Large OSL (portal, engine) | Airbrush or extensive glaze work | Advanced |
Recommended Brushes and Glaze Mediums
- Glaze medium — the single most useful OSL purchase
- Soft Taklon glaze brush (#2) — holds a thin, even coat
- Kolinsky detail brush (#0) — for reflected streaks
- Matte varnish — kills any accidental shine before you start glazing
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FAQ
Is OSL too advanced for beginners?
Simple two-glaze OSL on one small light source is a beginner-accessible technique. Save the 20-glaze portal engines for model number fifty.
What colour should I use for OSL?
Match the light source’s logic: fire = warm orange, plasma = blue/cyan, warp energy = violet or storm-green. The reflected colour must always match the source hue.
Do I need an airbrush for OSL?
No — an airbrush speeds up large surfaces, but glazes handle everything a tabletop model needs.
How do I combine OSL with weathering?
Weather first, glow second. OSL light passes over grime naturally — but paint order matters: pigments and chipping under glazes, never on top.
Continue on the Workbench
- 👉 How to Paint Glowing Plasma Effects — the beginner version of this technique
- 👉 Easy Weathering Techniques — how grime and glow interact
- 👉 Airbrush for Miniatures: Beginner Setup — when you’re ready to speed up
- 👉 Warp Travel Explained — the lore behind violet portal light
OSL is the difference between a painted model and a scene. One light source, two glazes, full commitment. Shop glaze mediums → (affiliate links)
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