Object Source Lighting (OSL)
Paint the effect of a light source on the model, like a glowing sword or magic spell illuminating nearby surfaces.
Object source lighting turns something on the model into a lamp — a glowing blade, a torch, plasma coils — and then paints what that lamp does to everything around it. Two rules carry the whole illusion. First, the source itself must be the brightest thing on the model, near-white at its core, because nothing looks lit by something dim. Second, light is honest: it lands only on surfaces that face the source, strongest up close, fading with distance, and never bends around a corner. And because a coloured glaze can only tint what's beneath it, we first rebuild the lit surfaces toward a pale near-white of their own colour — the brightness lives underneath, the glaze supplies the colour of the light.
Best For
Recommended Paint Types
Step-by-Step
Paint the source itself first: the light source — the blade, torch flame, or plasma coil gets your brightest tone at its centre, nearly white, ringed by the pure colour of the light.
Trace with a finger which surfaces face the source and how close they sit — those, and only those, receive light.
Re-highlight those receiving surfaces BEFORE any coloured glaze: build each lit patch up toward a pale, near-white version of its own colour, brightest nearest the source. A glaze can only tint — the brightness must already be underneath, or the glow dries as a dull stain.
Thin the light's colour (plus near-white for the source core and the pale pre-highlights) to skim-milk or thinner glazes and glaze those pre-highlighted surfaces with your size 1 round, wicked nearly dry, 3–4 coats close to the source, tapering to a single coat at the fringe.
Deepen the sell by darkening the surfaces facing AWAY from the source a touch — contrast is what makes the glow read.
Step back at arm's length between every few coats; the moment the glow reads clearly, stop — subtle OSL always beats loud OSL.
If It Goes Wrong
If the glow smeared somewhere light couldn't physically reach, repaint that patch in its original colours and re-fade the boundary; if the whole effect looks weak, don't add more spill — brighten the source's core instead, that's almost always the missing piece.
Pro Tips
Less is more. Subtle OSL looks way better than overdone OSL.
The light color should tint the receiving surface, not replace it entirely.
OSL works best on models that are otherwise darkly painted — the contrast sells the effect.
Fluorescent paints are unusually vivid and make source cores read as genuinely emissive — and they glow under UV as a bonus.
Red and purple light is hard: their saturated forms are dark, so hue-shift the core toward orange or pink to get real brightness.
Common Mistakes
Glazing the glow colour straight over dark paint with no pre-highlight — the classic dull, stained OSL.
Making the glow too strong — it should be subtle on most receiving surfaces.
Light reaching surfaces it physically couldn't (going around corners, through objects).
The light source itself not being bright enough — it needs to be the brightest point.
Applying OSL over bright basecoats — it's hard to see. Works best over dark schemes.