Guide · 7 min read
Object source lighting, painted right
OSL is the technique that makes a glowing sword actually look like it's lighting the hand holding it. Most attempts read as a smudge instead of a glow because the light never falls off. Here's the method, the real color temperatures, and the four ways it goes wrong.
PaintMini's Expert tier renders an OSL scheme on your own miniature before you commit a drop of paint.
Object source lighting (OSL) is a miniature-painting technique that paints a surface as if it were lit by a light source that exists inside the scene itself - a glowing blade, a lantern, a power core - rather than by the studio light overhead. The light color bleeds onto nearby surfaces and fades with distance, the same way a real light does. It's one of two techniques PaintMini's Expert tier unlocks, alongside non-metallic metal (NMM).
OSL vs. non-metallic metal - the two get confused constantly
Both are Expert-tier techniques and both involve painting light where there isn't any pigment for it, so new painters lump them together. They're solving different problems.
OSL
A light source that emits its own glow - a rune, a plasma coil, a torch. You're inventing a light and painting its effect on everything around it. See the four-step method below.
NMM
A metal surface with no metallic paint on it at all - painting the reflections, highlights and environment bounce that make flat acrylic read as steel or gold. Read the non-metallic metal guide for the method.
The four-step method
Every working OSL scheme breaks down the same way, whether it's a candle or a reactor core.
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Pick one light color and one intensity
Decide the hue (amber candle, cyan plasma, green rune) and how bright it is before you touch a brush. One light source per model unless you're deliberately painting two - mixed uncommitted light is the single fastest way to end up with mud.
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Map near vs. far
Everything touching the light source gets the full color at full strength. Surfaces a few centimeters away get a diluted version. Anything on the far side of the model gets none of it - light doesn't wrap around a torso.
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Blend the falloff, don't fade it evenly
Real light falls off fast near the source and slowly further out - an inverse-square curve, not a straight gradient. Paint two or three visibly distinct bands rather than one smooth airbrushed wash, or the glow reads as a stain.
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Add the hotspot last
A small, near-white core at the actual source - the tip of the blade, the center of the rune - is what sells the whole effect. Skip it and the surrounding glow looks like a colored smudge instead of a light.
Picking a color temperature
The color you choose tells the viewer what kind of light it is before they've consciously registered why. These are the standard starting points painters return to:
| Light source | Hue | Reads as |
|---|---|---|
| Candle, torch, campfire | Warm amber-orange | Comforting, organic |
| Plasma, power core, sci-fi tech | Cool cyan-white | Artificial, high energy |
| Arcane rune, toxin, poison | Acid green | Unnatural, dangerous |
| Warp energy, psychic power | Violet-magenta | Otherworldly |
| Molten metal, lava, explosion | White-hot core to red edge | Volatile, destructive |
A source photographed under daylight-balanced light will read differently once your phone's white balance corrects for it - check your reference photos in the same light you're painting under.
How long it actually takes
OSL is slower than it looks, and most of the time goes into the blending, not the color mixing.
- A standard highlight-and-wash scheme: roughly 1-2 hours for a 28mm infantry model, PaintMini's Beginner-tier time estimate.
- The same model with one OSL light source added: add 30-60 minutes - the falloff blend alone is usually three to five thin layers.
- A full Expert-tier scheme with OSL and NMM together: 6-10 hours, which is why it's reserved for a centerpiece model, not a squad of twenty.
The payoff shows up specifically in contest judging and photography - a light source that actually looks lit reads from across a table in a way flat highlights don't.
The four ways it goes wrong
No falloff
The glow color is painted at the same strength everywhere near the source instead of fading. Reads as a flat colored patch, not a light.
No hotspot
Every OSL attempt needs a near-white core at the source itself. Without it, the surrounding color looks smeared rather than emitted.
Wrong color temperature
A magic rune painted candle-amber reads as a torch, not magic. Match the hue to what the light is supposed to be, not to whatever's already on the palette.
Light that ignores geometry
Light doesn't wrap around a shoulder or bend around a cloak fold. If a surface is angled away from the source, it gets less light - painting it at full intensity anyway is the tell that gives away an unplanned OSL attempt.
OSL is hard to undo once it's blended into the base color. A rendered preview on your own miniature - what PaintMini's Expert tier generates - shows the light placement and falloff before you've mixed a single glaze.
Is OSL right for this model?
Three questions worth answering before you start:
- Does the model actually have a light source sculpted onto it? A blade, gem, or lantern gives OSL something to originate from. Inventing one on a model with no obvious source usually looks arbitrary.
- Is this a centerpiece, or one of twenty? At 30-60 extra minutes per light source, OSL on a full squad is a multi-day project. Save it for the model that's meant to stand out.
- Have you painted basic edge highlighting comfortably already? OSL is a falloff-blending skill built on top of highlighting fundamentals, not a starting point.
New to the vocabulary? The miniature painting glossary defines OSL, NMM, and every other term on this page in one place.
Questions people ask about OSL
What does OSL stand for in miniature painting?
Object source lighting - painting a surface as though it's lit by a light source inside the scene itself, like a glowing weapon or a lantern, rather than the ambient light of wherever the model sits.
What's the hardest part of OSL to get right?
The falloff. Painters get the light color right and the hotspot right, then paint the surrounding glow at one flat strength instead of fading it in two or three visible bands, which is what actually reads as light rather than a colored patch.
Is OSL the same as non-metallic metal (NMM)?
No. NMM paints a metal surface using no metallic paint at all. OSL paints the effect of an invented light source on the surfaces around it. Both are Expert-tier techniques and often appear on the same model, but they solve different problems - see the comparison above.
Can a beginner attempt OSL?
Not as a first project. It builds directly on edge highlighting and layered blending, so most painters get comfortable with those first. PaintMini gates OSL behind its Expert tier for the same reason.
How much longer does OSL make a paint job?
Roughly 30-60 minutes per light source on top of a standard highlight-and-wash scheme, mostly spent on the falloff blend rather than color mixing.
What paints do I need for OSL?
No special range - a light color, a lighter version of it for the falloff bands, and a near-white for the hotspot. Contrast and Speedpaint-style paints can shortcut the base glow layer, but the falloff blend is still done by hand.
See OSL on your own miniature first
Upload a photo of your primed model, pick Expert tier, and get a rendered preview with the light source placed before you mix a single glaze.