How to Prime Miniatures: Spray Can, Brush-on and Airbrush

Priming a miniature gives paint something to grip. Acrylic paint on bare plastic rubs off at the first handling; on primer it stays put, covers in fewer coats, and shows a consistent colour rather than the plastic underneath.

This guide covers the three ways to prime, how to get an even coat from a spray can without losing detail, which primer colour to choose for the scheme you have in mind, and how to recognise and fix a bad prime before you paint over it.

What does primer actually do?

Three things:

• Adhesion. Primer bonds to the plastic mechanically and gives the paint a slightly textured surface to key into.
• Uniform colour. A model built from grey plastic, a black weapon sprue and green putty is three colours. Primer makes it one.
• Coverage. Paint over primer needs fewer coats, which means thinner paint and more preserved detail.

Skipping it does not mean the paint will not go on. It means it will chip off the edges of every model you handle.

How do you prime with a spray can?

Rattle-can primer is the fastest route and the one most people use. It is also the easiest to get wrong, because the failure is caused by conditions rather than technique.

1. Check the weather. Ideally 15–25°C and low humidity. Cold air and damp are what cause a furry, sandy finish.
2. Shake the can for a full two minutes after the ball starts rattling. Under-shaken primer sprays as thin pigment-poor liquid.
3. Warm the can slightly in your hands if it has been in a cold garage.
4. Test on the sprue or a scrap. Always. It costs one second and catches a spitting nozzle.
5. Hold the can 20–30cm away. Closer floods the model; further and the paint half-dries in flight and lands as dust.
6. Spray in passes, not bursts. Start spraying before the model, sweep across it, release after. Two or three light passes from different angles beat one heavy one.
7. Rotate and repeat — front, both sides, then a light pass from above. Do not chase full coverage in one go.
8. Leave it to cure for an hour before painting, longer in cold weather.

You are aiming for a coat thin enough that the model still looks crisp and just opaque enough that no plastic shows through. Slight thinness in a recess is fine — nobody sees it.

When is brush-on primer better?

Brush-on primer solves the two problems the can cannot: weather and ventilation. If you live somewhere humid, or paint in a flat with no outdoor space, it is the sensible default rather than a compromise.

Apply it like a basecoat — thinned slightly, two coats, avoiding pooling. It takes longer per model and needs more care around recesses, but it never frosts and it wastes nothing.

It is also the right tool for touching up: a model that got missed on one side, or a repair after a break, can be spot-primed with a brush without re-spraying the whole thing.

How do you prime with an airbrush?

An airbrush gives the most control and the thinnest coats, at the cost of setup and cleaning. Use a primer formulated for airbrushing, thin it to the consistency of milk if it needs it, run 15–20 PSI, and build up in light passes exactly as with a can.

The real advantage is not the flat coat — it is that an airbrush lets you place the primer directionally, which is the basis of zenithal priming.

Which primer colour should you choose?

Primer colour sets the value your whole scheme sits on, and it is the fastest way to save or waste hours.

• Black makes everything above it darker and richer. Recesses shade themselves. It is unforgiving of thin coverage on flat panels, and bright colours over black need several coats.
• White makes colours bright and saturated. Every flaw shows, and it needs careful shading afterwards or the model looks washed out.
• Grey is the sensible middle. Colours read close to how they look in the pot.
• Bone or off-white warms everything above it and is the standard choice under contrast-style paints.

The general rule: choose the primer nearest in value to your final dominant colour. Black armour over black primer is one coat. Yellow armour over black primer is six.

Which primer for which Warhammer army?

• Ultramarines, Space Wolves, or any mid-to-bright blue — grey primer. Macragge Blue covers cleanly over grey and stays vivid.
• Iron Hands, Raven Guard, Black Templars, Death Guard — black. The scheme is mostly dark, so the primer is doing most of the work.
• Imperial Fists, or any yellow or orange army — bone or white, then a yellow basecoat. Yellow over black is the classic beginner trap.
• Tyranids, Aeldari, or anything you plan to paint with contrast-style paints — bone. The whole technique depends on a light, warm ground.
• T'au Empire, whose kits have large flat plates — grey or bone, since flat panels punish uneven coverage and mid-tone primer hides it best.

Paints to use

The Citadel sprays below are the common starting points; the brush-on and airbrush ranges from other brands do the same job.

Chaos Black · Citadel Colour Spray

Grey Seer · Citadel Colour Spray

Wraithbone · Citadel Colour Spray

Corax White · Citadel Colour Spray

What are the most common priming mistakes?

• Spraying too close. The primer goes on wet, pools in recesses and drowns detail. Back off to 20–30cm.
• Spraying in cold or humid air. This is what causes a gritty, frosted, "furry" finish — the paint dries before it lands. Wait for a better day or switch to brush-on.
• One heavy coat instead of three light ones. Heavy coats obliterate the fine detail you paid for.
• Not shaking the can enough. Produces a translucent, glossy coat with no grip.
• Painting over primer that has not cured. It stays soft, and your basecoat lifts it.
• Priming a model you are still going to glue. Plastic cement will not weld through primer.

How do you fix a bad prime?

Look at the model under a bright light before you paint. If the surface is gritty, chalky, or has visibly lost detail, deal with it now.

• Light frosting on flat armour can sometimes be knocked back with a very fine sanding sponge, then re-primed thinly.
• Bad frosting or a flooded model needs stripping. Isopropyl alcohol or a purpose-made stripper, an old toothbrush, and patience.
• Patchy, thin coverage just needs another light pass once the first has cured.

Stripping and re-priming an afternoon's work is annoying. Painting forty hours onto a bad prime is worse.

Frequently asked questions

Do I really need to prime miniatures?

Yes, for anything you intend to handle or game with. Paint on bare plastic chips off edges and rubs off raised areas. The only models you can reasonably leave unprimed are display pieces that never get touched.

What is the best primer colour for beginners?

Grey. Colours look roughly how they do in the pot, thin coverage is forgiving, and it suits both dark and light schemes.

Why did my primer go furry or sandy?

Almost always humidity or cold. The primer partly dries in the air and lands as powder instead of a film. Prime on a dry day between 15 and 25°C, or use brush-on primer indoors.

Can I use hardware-store spray primer on miniatures?

It works, but the pigment is usually coarser and the coat thicker, so fine detail suffers. Automotive primers in particular go on heavy. If you use one, test on a spare model first and keep the passes very light.

How long does primer need to dry before painting?

An hour is enough in warm, dry conditions. Overnight is safer in the cold. Primer that still smells strongly of solvent is not ready.

Can I prime an assembled model, or should I prime the parts?

Either. Priming parts on the sprue or on sticks gives better coverage in tight spots; priming assembled is faster and avoids scraping primer off glue points. If you prime parts, remember to keep the glue surfaces clean.

What comes next

With an even, cured primer coat you have a choice. Go straight to a basecoat for full control over every colour, or spend five more minutes on zenithal priming and let the primer do your shading for you.