Add (Glow) creates a stronger, more luminous effect than Add. It brightens the base layer by adding color values, but produces a more intense glow, particularly around soft or partially transparent areas.
The Math
Add (Glow) is closely related to Add, using the same basic idea of adding the colors of the blending layer to the base layer. The difference is in how strongly the effect responds to the transparency and brightness of the blending layer, producing a more concentrated glow.
Think of it as Add with the brightness response turned up: soft brushstrokes and partially transparent areas can produce a stronger atmospheric glow instead of simply adding a uniform amount of brightness.
Core Rules of Add (Glow)
Black does nothing: Pure black contributes no brightness, leaving the base layer unchanged.
Bright colors hit hard: Bright or highly saturated colors quickly push the underlying pixels toward white.
Soft edges glow: Partially transparent areas can produce a stronger atmospheric glow than the equivalent stroke on a standard Add layer.
Stronger than Add: Add (Glow) is more aggressive, so lower opacity can help keep the effect from becoming overwhelming.
When to Use It
Glowing effects: Use a soft airbrush with saturated colors such as cyan, neon yellow, or hot pink for magical effects, sci-fi lights, or laser fire.
Atmospheric glow: Blur a duplicate of a bright line or shape and set the blurred layer to Add (Glow) to create a soft aura around the light source.
Dark backgrounds: Add (Glow) is especially effective against dark or night-themed artwork, where the added light creates strong contrast.