Tutorial — Painting Object Source Lighting

How To Paint OSL

Make Your Weapons Actually Glow

Object source lighting looks like sorcery and isn't. It's three rules about how light behaves, a value ladder of saturated paint, and the patience to lay down a few thin coats in the right order. Learn the rules and you can make anything glow, in any color, forever.

Here's the cheapest magic trick in the hobby. Take a model nobody looks at twice, paint one weapon so it looks like it's throwing off light, and suddenly the whole thing reads as alive. People pick it up. They tilt it toward the lamp to figure out where the glow's coming from. That's object source lighting, OSL, and it's the single best return on five minutes of effort you will ever get at the painting desk.

It also looks, from the outside, like sorcery. It's not sorcery. It's three ideas about how light behaves, plus the patience to put down a few thin coats in the right order. Learn the three ideas and you can make anything glow, in any color, forever, no matter what paints exist on the shelf when you read this. Skip them and you'll keep wondering why your glowing sword just looks like a sword someone painted bright blue.

I wrote a version of this tutorial back in 2013. It worked, but it was a recipe — mix this exact paint with that exact paint. The problem with recipes is the ingredients keep getting discontinued. So this is the rebuild. The why under the what, so you're never stranded when a paint range changes on you. Which it will. More on that in a minute.

First, the part nobody can skip: how light actually works

You cannot fake something convincingly until you know what the real thing does. Light isn't complicated, though. Three rules carry the entire technique.

Light travels in straight lines. Picture a little sun sitting at your light source, throwing beams outward in every direction. Surfaces facing the source catch the most light. Surfaces turned away from it stay dark. Anything tucked behind something else, in the shadow it casts, gets nothing. That's it. Once you decide where your glow lives, you can trace those straight lines in your head and know exactly which surfaces should light up and which stay black.

Distance equals dimness. The light is hottest and most saturated right at its origin, pure white or screaming neon at the core, and it gets darker and weaker the farther it travels across the model. A blade's glow is blinding at the edge of the blade and barely a whisper by the time it reaches the wielder's elbow. Paint that falloff and your eye buys it completely.

The light is never brighter than the source. This is the one people break constantly, and it's the one that wrecks the illusion. The thing making the light — the energy coil, the lantern, the daemon sword — has to be the single brightest object in the scene. The glow it casts onto the armor, the hand, the face, must always be a step dimmer than the source itself. The moment the spill looks as bright as the lantern, your brain stops reading 'lantern' and starts reading 'someone painted two bright spots.' Source brightest, spill dimmer. Always.

Get those three straight and you already understand OSL better than half the people who've been avoiding it for years.

Second: painting the glow

Now the paint. The whole effect is a value ladder, dark and saturated at the bottom, blinding white at the top, climbing in thin steps.

Start by painting your model normally, like the glow isn't there at all. OSL goes on last, on top of a finished mini. Then block in your core ambient color, the base hue of your light, over the source and the surfaces nearest it. Build brighter from there in thin coats, each one covering a smaller area closer to the source than the last, until you finish with a tiny hit of near-pure white at the absolute hottest point. Saturated base, brighter mid, white core. That ladder is the whole game.

And here's where the color matters, because OSL lives and dies on saturation. Normal paints are too muted to read as emitted light. You want fluorescents — the obnoxious, eye-searing, why-would-anyone-paint-a-model-this-color fluo paints. That unreal vibrancy is exactly what tricks the eye into seeing light instead of pigment.

Here's what I'd actually reach for today, and you'll notice I'm steering you toward third-party, alternative paint brands and indie paint makers, because they're doing this better and we like them more:

The Army Painter Warpaints Air Fluorescent range is purpose-built for this — six airbrush-ready fluorescents made for OSL, and their newer Warpaints Fanatic "Effects" line has glow-named colors like Lens Flare Glow and Radiation Glow that are basically OSL in a bottle. For a Dark Eldar violet weapon like the ones in these photos, their fluorescent pink/purple is the heir to every gross-bright DE glow ever painted.

AK Interactive's fluorescent acrylics thin beautifully for the airbrush and come in the full spread of glow colors. If you're already an AK airbrush user, you're set.

Turbo Dork's fluorescent "Flourish" paints are the loudest neon on the market, full 80s-arcade vivid. I reach for these when I want the hottest part of a glow to genuinely punch — less the smooth gradient body, more the screaming core accent.

And if you just want the easy-to-find shelf staple, Vallejo Game Color Fluo (Fluo Violet, Fluo Cold Green, Fluo Blue, Fluo Red) is everywhere and does the job. That's the modern descendant of the Vallejo fluo I used in the original 2013 version of this, so there's a nice continuity there.

Pick a fluorescent in your chosen color, get some white, and you have everything you need.

Here's that ramp broken into five steps. Each coat covers a smaller, brighter area than the last, walking your eye straight up the value ladder to the source.

Airbrush or brush, both work

Let me kill the biggest myth right now. You do not need an airbrush for OSL. An airbrush is great at it, because spraying paint behaves a lot like spraying light — soft gradients fall right out of the tool, and that's why I prefer it. But I was doing this with brushes long before, and you can too. Drybrushing the glow color outward from the source (brush only ever moving away from the light, never back toward it) builds the gradient in passes. Thin glazes and washes do the blending for you. The technique is the principle, not the gadget. Anybody telling you OSL requires an airbrush is selling airbrushes.

If you do airbrush it, thin your fluo heavily, drop your pressure low, keep the needle close, and build in light passes rather than one heavy hit. Soft and slow wins. Control the spray radius by distance — closer for the tight hot core, pulled back for the wider ambient spill.

A shortcut for patterned glows

One trick the original tutorial didn't have. If your glow isn't a simple blob but an actual pattern — energy shielding, glowing circuitry, tribal markings lit from within — you don't have to freehand that misery. Lay down a Fallout Hobbies stencil and airbrush your fluo through it, and you get crisp, repeatable glowing patterns with none of the shaky-hand heartbreak. Hex mesh for energy fields or hazard markings for reactor glow. Stencil first, glow through it, done.

Third: contrast is what sells it

You can mix the perfect glow color and still end up with a model that looks flat, because OSL isn't really about the bright part. It's about the difference between the bright part and everything else. Contrast is the whole illusion.

Darken the rest of the model. A glow surrounded by mid-tones barely registers. The same glow surrounded by deep, muted shadow looks like it's burning a hole in the dark. If you want the light to scream, make the rest of the mini whisper. Knock the surrounding tones down, mute them, and let the glow be the loudest thing on the table.

Paint shadows on the dark side. Light hits one side, which means the other side falls into shadow, and most people forget to paint that half of the equation. Deepen the shadows on the surfaces turned away from your source. The contrast between the glowing near-side and the swallowed-up far-side is where the drama lives.

This is also, conveniently, why OSL is so forgiving. A clean glow on a flat-lit model looks okay. A messy glow on a high-contrast model looks incredible, because the eye is so busy reading the drama of light-versus-dark that it forgives a wobbly blend. Lean into contrast and the technique covers for you.

Watch it happen

Reading about gradients only gets you so far. Here's the technique in motion — airbrushing an object-lighting effect onto a daemon prince's sword to give Be'lakor a blade worth slashing across a few Space Marines. Different model than the Scourges in this article, exact same method start to finish, and seeing the paint go down in real time makes the value ladder click in a way no diagram can.

And here's the finished Be'lakor on the turntable, OSL and all. This is what that value ladder looks like once it's dry and spinning under the lights.

The payoff, and an honest word about the models

Here's the technique on a few finished Dark Eldar, so you can see the same five-step ladder working in two completely different colors. First the violet:

And the exact same technique in turquoise, to prove the ladder doesn't care what color you climb it in:

Quick honesty, because the hobby moves and these minis are a decade old. The winged ones are Scourges, and good news — they're alive and well, still a current Drukhari unit and actually buffed in the latest codex. The serpent-bodied one is an Sslyth from the old Court of the Archon, and that whole unit got cut in the most recent Drukhari book, packed off to Legends with a bunch of other classics. So one of these you can still buy and field today, and the other's a relic of a bygone roster. Doesn't matter even a little for our purposes. The glow technique is identical whether you're lighting a current-codex plasma weapon or a thirteen-year-old conversion the rules forgot. That's the entire point of learning the principle instead of the recipe — the models change, the editions change, the paint ranges change, and the way light works does not.

Now go make something glow.