Airbrush Highlight & Shadow (Post-Shading)

Short answer: Airbrush post-shading is a way to sculpt volume after the basecoat is down. You spray a lighter tone (the highlight) onto the upper, lit surfaces and a darker tone (the shadow) into the recesses and undersides. The payoff is speed: on big monsters, vehicles, and broad panels it gives you the smooth gradients that take hours with a brush, but only minutes with an airbrush.

Let's separate two terms up front. Pre-shading sets the shadow before colour; post-shading adds highlight and shadow after colour. So you work on top of the finished basecoat, feeding the light tone where the light hits and the dark tone into the recesses it never reaches. The secret comes down to three things: transparent paint, low PSI (low air pressure), and a consistent light direction.

What is post-shading and what is it for?

As the name suggests, post-shading is a technique that kicks in once the basecoat is finished. You add highlight and shadow with an airbrush to give the model a three-dimensional feel, all without ever touching the surface with a brush.

Its real power shows on large surfaces. Picture huge monsters, tanks, cloaks, and armour panels: layering those broad areas smoothly with a brush (thin coat after thin coat) takes hours. The airbrush, by contrast, lays the same gradient in minutes, with no brush marks at all.

So when should you use it? The answer is simple: on broad, continuous surfaces, whenever you want a soft volume transition. It is not the tool for crisp edge detail, which you add later with a brush. In short, post-shading builds the volume; the brush adds the sharpness.

There is also the bonus of repeatability. When you batch-paint five big monsters from the same army, you can apply the same highlight-and-shadow logic to each in minutes with the airbrush. Pulling off that consistency by brush is both tiring and prone to drifting from model to model.

How does it work?

At the heart of the technique is the airbrush's graduated spray, which feeds light and shadow into the surface softly, with no hard border. You start the paint at one point and squeeze it into a shrinking area, so the edges fade out in a soft transition instead of a sharp line.

On the highlight side, you spray the lighter tone (or a lighter version of the base colour) only onto the upper, lit surfaces, in an ever-smaller area. A gentle light accent in the centre of each panel gives that classic colour-modulation feel (colour modulation means shifting the tone within a single panel).

On the shadow side, you spray the darker tone into recesses, undersides, and panel edges. Falloff is critical here. Falloff means the shadow starts dense in the recess and fades toward the raised edge. Using transparent or semi-transparent paint lets you shift only the tone without drowning the colour underneath, which is exactly why paint consistency matters so much.

The principle Marco Frisoni repeats on broad surfaces holds true here too: the airbrush builds the volume, the brush adds the sharp detail. You get the strongest result when you use them together. Expect crispness from the airbrush alone and you will only end up disappointed.

How do you do it step by step?

Let's set the theory aside and head to the bench. Post-shading is really just feeding the shadow first and then the highlight onto a basecoated model. Here is the order you actually work in:

1. Have the base colour ready: The basecoat should be down and fully dry first, because post-shading always works on top of the base colour.
2. Spray the shadow: Feed the dark, transparent tone into the recesses and undersides the light never reaches, in thin passes at low PSI. Don't forget the falloff: dense in the recess, fading toward the raised edge.
3. Spray the highlight: Now for the light. Feed the light tone onto the upper, lit surfaces, in a shrinking area. Place a gentle light accent in the centre of each panel.
4. Balance it: Hold the model away from you and check the contrast from a distance. If needed, strengthen the shadow and highlight gradually, in layers rather than all at once.
5. Mask (optional): Use masking where you need a crisp shadow or highlight border.
6. Brush touch-ups: Finally, finish the fine edge highlights and point details with a brush. The sharpness on top of the airbrush's softness comes in this step.

Which paints and tools?

Here's the good news: post-shading does not demand a long shopping list. Half the job comes down to the right paint consistency and low-pressure control. Still, these are the things worth having on hand:

• Airbrush + compressor: A setup you can spray in a controlled way at low PSI. Good atomisation (the paint breaking into fine particles in the air) matters for fine highlights.
• Transparent/semi-transparent paint: Vallejo, Citadel, or similar brands; aim for a consistency that tints rather than covers the colour beneath.
• Glazing medium: An additive that turns opaque paint transparent and post-shade ready. It thins the paint without killing its colour strength.
• Masking material (optional): For panels or areas that need a crisp border.

The level is medium-to-advanced, but on a large surface the result comes quickly. The single most critical choice here is keeping the consistency transparent. Don't thin in the pot; thin step by step with a dropper in the airbrush cup, because even heavily thinned transparent paint shows its strength after a few coats. A patient few thin coats always give a cleaner volume than one rushed thick coat.

The most common mistakes

The good news is that the traps in post-shading nearly always fall under the same four headings. And most of them come from skipping either the light logic or the transparency:

• Inconsistent light direction: Highlight from the top in one place and from the side in another, and the volume gets confusing. That is why you should pick a single light direction and stay loyal to it across the whole model.
• Post-shading with opaque paint: Covering paint drowns the base colour and leaves a flat, fake patch. To avoid this, always use transparent paint or a glaze.
• Skipping the falloff: Laying shadow and highlight with a hard border looks flat and artificial. Instead, fade the density gradually from recess to raised edge.
• High PSI / too close: Too much pressure and spraying too close cause blotches and overspray (unwanted spray drifting where you don't want it). The fix is low PSI, thin coats, and a sensible distance.

Pro tips

A few small habits lift post-shading from an amateur field of patches to a real sense of volume. Here are the ones that help most:

• Keep it transparent: Always work post-shade transparent; do not fully cover the colour beneath, just tint it. The effect builds layer by layer, not in one pass.
• Panel logic: Highlight the centre of the panel, shadow the panel edge. This sets up the classic modulation feel in the most natural way.
• Airbrush + brush: The airbrush gives the volume, the brush the sharp detail. Used together, they produce the strongest result.
• Think of related techniques together: Pair post-shading with Airbrush Zenithal Preshading and Airbrush Blending & Gradient; one comes before colour, one is the basis of the transition, and post-shading comes after colour.

When you want to shift colour transparently, Airbrush Glazing and, for within-panel light and shade, Marbling & Colour Modulation are natural neighbours. And for the conceptual basis behind all of this, look at Pre-Shading & Post-Shading too.

Frequently Asked Questions

What is the difference between pre-shading and post-shading?

Both add shadow and highlight, but the timing differs. Pre-shading works before colour: you shade the ground first, then glaze transparent colour over it. Post-shading works after colour: the basecoat is finished, then highlight and shadow go on top. So pre-shading plans the lighting from the start, while post-shading adds volume to a finished colour. The two are not rivals but complements.

What PSI suits post-shading?

The general rule is low pressure. High PSI and a close distance cause blotches and overspray, and you lose control. At low PSI you work in thin passes and build the paint up layer by layer. The exact number depends on your setup and paint consistency, so test on a scrap piece first and move to the model once you are sure.

Can I post-shade with opaque paint?

Technically you can, but it is not recommended. Opaque paint drowns the base colour and leaves a flat, artificial patch. The point of post-shading, though, is to shift the tone, not to cover the colour. So keep the paint transparent or semi-transparent, or thin it with a glazing medium; the colour beneath should stay visible.

What is falloff and why does it matter?

Falloff is the gradual fading of shadow or highlight density: the shadow is dense in the recess and fades toward the raised edge. Skip it and leave a hard border, and the volume looks flat and fake. For a natural volume, always grade the density gradually; after all, that soft fade is exactly the airbrush's real strength.

Do I need a brush after post-shading?

Usually yes. The airbrush gives soft volume nicely but leaves no crisp edge detail. That is why you finish the fine edge highlights, point accents, and high-contrast edges with a brush. In short, the airbrush builds the volume, the brush adds the sharpness; the strongest result comes from combining the two.

Which models benefit most?

It shines most on broad, continuous surfaces: huge monsters, vehicles, tanks, cloaks, and large armour panels. Layering those areas smoothly with a brush takes hours, while the airbrush lays the same gradient in minutes. On small, detailed human figures you rely more on brush techniques.

Key takeaway and next step

To sum up, the essence of post-shading fits in one line: over the basecoat, with transparent paint and a consistent light direction, feed the shadow into the recess and the highlight onto the raised edge. Low PSI, gradual falloff, and a final brush touch-up; nail that trio and large surfaces gain volume in minutes.

If you want to build your own post-shading kit with an airbrush, transparent paint, and a glazing medium, start with our paints, brushes & hobby supplies. But take your time: try it on a scrap model first, and as long as you stay loyal to the light direction, the rest follows on its own.