Advanced OSL — Painting Bioluminescence on VoidHive Forge Models

Object Source Lighting — OSL — is the technique of painting a model as if it is being illuminated by a light source on the model itself. Done well, it is one of the most striking effects in miniature painting. Done poorly, it looks like someone spilled paint. This guide will help you do it well.

For VoidHive Forge models, OSL is not just a stylistic choice — it is the defining technique of the range. The bioluminescent sacs, vein channels, and eye clusters on every VoidHive sculpt are designed to glow. This is how oʻyou make them.

Understanding OSL

OSL works on a simple principle: light from a source illuminates nearby surfaces. The closer a surface is to the light source, the brighter it appears. The further away, the darker. The light also tints surrounding surfaces with its colour — a green glowing sac casts green light on the chitin around it.

To paint OSL convincingly, you need to think about three things: the source, the falloff, and the colour cast.

Step 1: Establish the Light Source

Identify which parts of your model will glow — bio-sacs, vein channels, eye clusters. These are your light sources. Paint them first:

• Basecoat the area white
• Apply your glow colour (Moot Green, Baharroth Blue, Flash Gitz Yellow) thinly over the white
• Build up the intensity toward the centre with additional thin coats
• Add a tiny dot of pure white at the very brightest point

Step 2: Paint the Falloff

The glow doesn't stop at the edge of the sac — it spills onto surrounding surfaces. Using a very thin glaze of your glow colour (heavily diluted with medium or water), apply it to the surfaces immediately surrounding the light source. The effect should be subtle — a tint, not a coat. Build it up in thin layers, concentrating the colour closest to the source and fading it out as you move away.

Step 3: Adjust the Shadows

OSL also affects shadows. Surfaces facing away from the light source should be darker than they would otherwise be — the light isn't reaching them. Deepen the shadows on the opposite side of the model from your light source using a dark wash or glaze. This contrast is what makes the OSL read as real light rather than just a coloured patch.

Step 4: Colour Temperature

For maximum impact, use a warm/cool contrast. If your OSL is a cool green or blue, make the surrounding shadows warm (purple, brown). If your OSL is a warm yellow, push the shadows cool (blue-grey). This contrast is what the eye reads as light — it's the same principle used in film lighting and concept art.

Common Mistakes

• Too opaque: OSL glazes must be thin. If you can't see the surface colour beneath, dilute further.
• No falloff: The glow must fade. A hard edge kills the illusion.
• Ignoring geometry: Light travels in straight lines. Only surfaces that face the light source receive the glow.
• Forgetting the source: The light source itself must be the brightest point. If the surrounding glow is brighter than the sac, something has gone wrong.

Final Thoughts

OSL is a technique that rewards practice. Your first attempt will be imperfect. Your fifth will be convincing. Your tenth will make people stop and stare across the table. VoidHive Forge models are built for this — every bio-sac and vein channel is a canvas waiting for light.

The Hive glows. Make it glow.