Short answer: Underpainting means building your light and shadow (your value) in a separate layer before you ever touch colour. The idea is simple: you perfect the form in a single tone first, then glaze transparent colour over it. It lifts busts and display pieces dramatically, though for tabletop armies it's usually overkill.
The logic comes from classical painting, and it's an easy one to grasp: the eye reads form from light-and-dark before it reads hue. So if you solve value on its own first, everything else falls into place. On top of that, underpainting isn't one technique but a small family, and the type you pick depends largely on the final colour you're aiming for.
What is underpainting and what is it for?
In short, underpainting is the umbrella term for building your value (and sometimes a colour foundation) separately from colour itself. The family comes in a few flavours: grisaille (grey), verdaccio (greenish), brunaille (brown), and imprimatura (a thin, single-colour wash over the whole surface).
Different names aside, they all do the same job: they separate value and form work from colour, then "dress" that structure with transparent colour layers. And you're not chained to grey-and-white while doing it. As Goonhammer's underpainting guide stresses, even for a metallic finish (say, Alpha Legion blue) you can build an underpainting that runs from dark metal to bright silver.
So where does all this effort actually pay off? Its real home is busts, display figures and showcase-quality single models, where it's a genuine level-up. For a 28mm tabletop army, on the other hand, it's usually too much.
How does it work?
It rests on one simple fact: the human eye reads volume from value first. Underpainting lets you perfect that value on its own, with no colour noise to distract you. The transparent colours you glaze on afterwards then leave that finished skeleton intact; they sit on top and inherit the light and shadow underneath as-is. Put in one sentence: you solve the hard problem (form) first and the easy one (colour) second.
That's exactly why underpainting lets you tackle two separate problems one at a time. First you wrestle only with light-and-dark, without trying to choose colours and build volume at the same moment. By the time you reach the colour stage the value is already settled, so you simply dress it with the right hue. In this way, the "think about everything at once" burden that wears beginners out disappears.
This is also where the type matters: the undertone you choose gives the final colour a different character, because the same colour over a grey skeleton reads differently depending on the warmth of the tone beneath it. Here's how the types compare:
- Grisaille (grey): Neutral and the most common choice. It works under any colour, so it's the safe starting point.
- Verdaccio (green-grey): The classic skin-painting secret. A green undertone balances the warm flesh tone above it and gives natural-looking skin. A Renaissance trick.
- Brunaille (brown): A warm brown undertone. Ideal for wood, leather and warm colour schemes.
- Imprimatura: More about unity than value. A thin, semi-transparent single colour (say a warm orange) over the whole surface gives every later colour a shared underlying warmth.
How do you do it, step by step?
At heart, underpainting is a two-stage job: value first, colour second. Most of the work lives in that first stage. The general flow runs like this:
- Pick the type. Start with your final colour: grisaille for a neutral scheme, verdaccio or a red imprimatura for skin, brunaille for a warm scheme.
- Build the value. With your single tone, lay in highlight, shadow and mid-tone smoothly. This is the skeleton of the piece, so don't rush it.
- Check the value. Before colour, stop and ask: are the volume, transitions and contrast right? Fix any doubts here, not later.
- Glaze colour on. Once the value is settled, apply transparent colours (a glaze is a heavily thinned, see-through layer) in stages, letting the colour inherit the value below.
- Add warmth and saturation. Next, use local glazes to enrich the colour and wake up any flat, lifeless areas.
- Accent. Finally, push the brightest and darkest points one last time, now in colour.
If you want a faster variant, see Zenithal Underpainting + Glazing Workflow, and for the grey version see Grisaille Underpainting.
Which paints and brushes?
The good news is the materials are plain. What really matters here is transparency and clean value transitions, so it's those, not expensive gear, that you should focus on.
- Acrylic paint for the underpainting tone: grey, green-grey, brown or a coloured imprimatura.
- Transparent colours and a glazing medium for the colour stage.
- A good detail brush and a wet palette to keep your value transitions under control.
- If you like, an airbrush for fast underpainting; it drops zenithal-style value work down to minutes.
Per Goonhammer's underpainting guide, you don't have to tie underpainting to grey-and-white. Even for a metallic final colour you can build an underpainting that runs from dark metal to bright silver, then glaze colour over the top.
The most common mistakes
There's a hard truth to know up front: underpainting is unforgiving, because colour won't rescue a value you built badly. The usual stumbles are these:
- Building the value sloppily. A bad foundation shows through everything you put on top, so this is where your time belongs.
- Making the glazes opaque. If the colour layer isn't see-through it smothers the underpainting and all your work vanishes. In other words, transparency is non-negotiable.
- Choosing the wrong type. Forcing a warm brunaille under a cool scheme, for example. When the undertone fights the final colour, the result goes muddy.
- Full underpainting where it isn't needed. A full grisaille on a 28mm tabletop model is usually wasted effort; zenithal priming normally does the job.
Pro tips
A few practical rules make this much easier:
- Match the type to the final colour. For skin, verdaccio (green) or a red imprimatura gives legendary results; pair this with Face & Skin Painting.
- Push the contrast a touch. Colour glazes always soften the value, so leaving the underpainting slightly over-contrasted lands it right.
- Use it at the right scale. It's a game-changer on busts and display, but on small tabletop, slapchop is more efficient.
- Study references. Goonhammer's underpainting guide and classic portrait technique are the most solid sources here.
Frequently Asked Questions
Is underpainting the same as zenithal priming?
Not quite. In fact, zenithal priming is a fast, airbrush-focused subset of underpainting: white sprayed from above over a black prime builds value in seconds. Classic underpainting, by contrast, is brush-led, more controlled, and works through types like grisaille and verdaccio. In short, zenithal is the practical, small-scale version of the same idea.
Why use a green underpainting for skin?
The green-grey undertone called verdaccio comes from the Renaissance, and the reason is simple: green is the complement of flesh tone. Sitting underneath, it balances the warm pink-beige tones above and gives skin a natural, non-waxy depth. Pure warm colours stacked together tend to look plastic, whereas the green undertone breaks that up.
Should I pick grisaille or imprimatura?
It depends on what you're after. Grisaille is for building value: you work full light and shadow in greys. Imprimatura, on the other hand, isn't about value but unity; a thin single colour over the whole surface gives later layers a shared underlying warmth. So if you want to work volume, use grisaille; if you only want atmosphere, use imprimatura.
What colours do I put over an underpainting?
Use transparent, heavily thinned glazes, because the goal is to keep the value below visible. An opaque basecoat would erase the whole underpainting. Instead, build colours thinned with glazing medium in stages, near-dry and controlled, so the value keeps reading through every pass.
Does underpainting make sense for a tabletop army?
Usually no. Full underpainting is slow and two-stage, so across 50 models it becomes wasted effort. For tabletop, zenithal priming, slapchop or contrast paints are far more efficient. Save underpainting for character models, commanders, busts and display pieces.
How do I know my underpainting contrast is enough?
There's an easy way to check: before colour, step back from the model or photograph it in black and white. If the volume, transitions and the highlight-to-shadow split read clearly, you're ready. If it looks vague, push the contrast a bit further; since colour glazes soften value, extra contrast always works in your favour.
Do I need an airbrush for underpainting?
No, you don't. An airbrush is great for fast underpainting (especially zenithal), but it isn't required. Classic grisaille and verdaccio can be done entirely by brush, with a wet palette and glazing medium. So the airbrush shortens the time; it doesn't determine the result on its own.
Key takeaway
In the end, underpainting has one core idea: separate value from colour, perfect the light and shadow first, then dress it with transparent glazes. As you do, match the type to your final colour, push the contrast slightly, and reserve this effort for busts and display models.
To start this workflow you'll want the right acrylic tones, a glazing medium and good detail brushes, so browse the shop's paints, brushes & hobby supplies; the right materials make underpainting far easier.