How to Thin Paints for Miniatures

Thin your paints by adding a small amount of water (roughly 1:1 ratio for Citadel paints) until the consistency resembles milk. This is the single most important technique in miniature painting — thick paint obscures detail, creates unwanted texture, and makes your models look messy.

Every experienced miniature painter will tell you the same thing: thin your paints. It sounds almost too simple to be the most critical skill in the hobby, yet it genuinely is. Whether you’re painting your first Combat Patrol or your hundredth character model, proper paint consistency determines the difference between a model that looks professional and one that looks like it was dipped in house paint.

This guide covers everything you need to know about thinning paints for miniatures — from the basic water method to advanced mediums, consistency tests, and which paints need special treatment.

Why You Need to Thin Your Paints

Acrylic miniature paints come out of the pot or dropper bottle at a consistency designed for storage stability, not for painting fine details on 28mm models. Straight from the pot, most paints are too thick for miniature work. Here is what happens when you don’t thin:

Detail loss — Thick paint fills in the crisp edges, rivets, and fine sculptural details that make a model look good
Visible brush strokes — Unthinned paint leaves streaky, uneven texture across flat surfaces
Colour coverage issues — Paradoxically, one thick coat often covers worse than two thin ones because it pools unevenly
Longer drying time in wrong places — Thick paint pools in recesses and takes ages to dry, while thin areas dry too fast
Paint cracks — Very thick applications can crack as they dry, ruining the finish

When you thin your paints properly, each coat goes on smoothly, preserves detail, and builds up colour gradually. The mantra “two thin coats” exists for a reason — it’s faster, looks better, and is more forgiving than trying to get perfect coverage in one go.

The Basic Method: Water

Water is free, always available, and works perfectly for most miniature painting situations. Here is the process:

Load your brush — Dip your brush into the paint pot and pick up a small amount on the tip
Touch water — Dip just the tip of your brush into clean water. You don’t need much — a tiny amount goes a long way
Mix on palette — Work the paint and water together on your palette until evenly mixed
Test the consistency — Draw a line on your thumbnail or palette. It should flow smoothly and be slightly translucent
Apply to model — Paint in smooth, even strokes. The first coat will look patchy — that is normal and correct

The classic ratio is roughly 1:1 paint to water for Citadel Base paints. Layer paints typically need less water (they’re already thinner). Contrast paints and washes should not be thinned further unless you’re doing advanced techniques.

The Milk Consistency Test

The most common description of properly thinned paint is “the consistency of milk.” But what does this actually mean in practice?

When you drag your brush through properly thinned paint on a palette:

It should flow smoothly off the brush without clinging in globs
A line drawn on your thumbnail should be slightly transparent — you can see skin colour through it faintly
The paint should not run uncontrollably or pool at edges when applied to a model
It should self-level slightly, meaning brush strokes partially disappear as the paint settles

If the paint is too thin, it will run into recesses like a wash and barely leave colour on raised areas. If it’s too thick, it will leave visible brush marks and cling to details. The sweet spot is narrow but forgiving — you’ll develop a feel for it quickly with practice.

Water vs Acrylic Medium vs Flow Improver

Water isn’t the only option for thinning, and for some techniques, it’s not even the best one. Here is how the three main thinning agents compare:

Water

Best for: General thinning, everyday painting, beginners
Pros: Free, always available, easy to control
Cons: Too much breaks the paint’s acrylic binder, causing it to bead up and lose adhesion
Limit: Don’t go beyond roughly 1:3 paint-to-water or the paint becomes unreliable

Acrylic Medium (Lahmian Medium, Vallejo Glaze Medium)

Best for: Glazing, extending paint without losing binding strength
Pros: Maintains paint integrity no matter how much you add, creates transparent layers
Cons: Costs money, slightly different handling feel than water
Use when: You need very thin transparent layers (glazing) or are mixing paint heavily

Flow Improver (Vallejo Airbrush Flow Improver, Liquitex)

Best for: Reducing surface tension, preventing tip-drying on fine brushes
Pros: Helps paint flow off the brush smoothly, reduces brush strokes
Cons: Too much makes paint behave unpredictably, doesn’t thin as much as water
Use when: You’re getting frustrated with paint drying on the brush tip or leaving streaks

Most painters use water 90% of the time and keep a pot of medium on hand for glazing and advanced techniques. Flow improver is a nice-to-have but not essential.

Two Thin Coats: The Golden Rule

The phrase “two thin coats” has become the unofficial motto of miniature painting for good reason. Here is why this approach works:

First coat: Goes on slightly translucent. You can see the primer or previous colour through it. This is correct — resist the urge to add more paint. Let it dry completely (5-10 minutes with properly thinned paint).

Second coat: Builds on the first, creating solid, smooth, opaque colour. The detail remains crisp because each layer is thin enough to flow around sculptural features rather than burying them.

Some colours need three or four thin coats — yellows, whites, and bright reds are notorious for poor coverage. This is normal. Each coat brings you closer to smooth, even coverage without sacrificing any detail. The result is always superior to one thick coat, even if it takes a few minutes longer.

Which Paints Need More or Less Thinning

Not all paints come out of the pot at the same consistency, and different brands have different formulations:

Citadel Paints (Games Workshop)

Base paints: Thick and high-pigment. Thin roughly 1:1 with water
Layer paints: Already thinner. Add just a touch of water — maybe 2:1 paint to water
Contrast paints: Pre-thinned for their specific purpose. Don’t add water unless doing advanced work
Shade paints: Already at wash consistency. Use straight from the pot
Dry paints: Designed to be used with almost no water for drybrushing

Vallejo Paints

Model Color/Game Color: Dropper bottles mean more consistent starting point. Thin slightly — a drop of water per two drops of paint
Generally thinner than Citadel out of the bottle — Vallejo paints need less thinning overall

Army Painter

Warpaints Fanatic: The new range has good consistency from the dropper. Light thinning needed
Speedpaints: Like Contrast, don’t thin these for normal use

ProAcryl, Kimera, Scale75

Premium ranges designed for serious painters. Generally come at near-perfect consistency and need minimal thinning for brush work

The Wet Palette Connection

A wet palette is a plastic container with a damp sponge and parchment paper on top. It keeps your paint wet for hours (or days) instead of minutes. This transforms the thinning process:

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Consistent moisture — The wet palette continuously adds tiny amounts of moisture to your paint, keeping it at a workable consistency
Less waste — Paint doesn’t dry out and get thrown away
Easier thinning — You can add water once and the palette helps maintain that consistency
Colour mixing — Mixed colours stay usable for hours, making matching easier

You can buy a wet palette (Redgrass Games, Army Painter, Masterson’s) or make one from a takeaway container, kitchen sponge, and baking parchment. Either way, it’s the single best quality-of-life purchase for miniature painting after good brushes.

Common Thinning Mistakes

These are the errors most beginners make when learning to thin paints:

Not thinning at all — The most common mistake. If paint comes out of the pot looking thick, it needs thinning
Thinning too much — Creating a wash when you wanted a basecoat. If paint runs into recesses uncontrollably, it’s too thin
Inconsistent mixing — Not fully incorporating water into paint, leaving streaks of thick and thin
Using dirty water — Thinning with brush-cleaning water tints your colours. Use a separate clean water cup
Impatience with coverage — Seeing the translucent first coat and adding more paint to compensate, defeating the purpose
Not drying between coats — Applying the second coat before the first is fully dry, which lifts paint and creates mess

How Do You Know When Paint Is Too Thick?

Paint that is too thick for miniature work shows clear warning signs. When you apply it to a model, you will see visible brush strokes that don’t self-level. The paint will cling to raised edges and fill in fine details like engraved lines, rivets, and textured surfaces. On your palette, thick paint will hold its shape when you push it with a brush rather than flowing. If you draw a line on your thumbnail with thick paint, the line will be fully opaque with sharp, defined edges — properly thinned paint would show some transparency and have softer edges.

How Do You Know When Paint Is Too Thin?

Over-thinned paint behaves more like a wash than a paint. When applied to a model, it immediately runs into recesses and pools in the lowest points, leaving raised surfaces barely coloured. On your palette, it looks watery and almost transparent. The paint has lost its body — it won’t stay where you put it. If you find yourself doing five or six coats and still not getting coverage, your paint is likely too thin. Add more paint to your palette mix and try again.

Can You Thin Every Type of Paint?

Most acrylic miniature paints benefit from some thinning, but certain products are pre-thinned for their intended purpose. Contrast paints, Speedpaints, and shade washes are formulated to work at their out-of-bottle consistency. Thinning them further changes their behaviour — sometimes usefully (for glazing effects), but often negatively (loss of the recess-shading effect they’re designed for). Technical paints like texture paints should never be thinned. Metallics can be thinned but behave differently — the metallic flakes separate from the medium more easily, so thin less and stir frequently.

Does the Type of Water Matter?

For most painters, tap water works perfectly fine. However, if your local water is extremely hard (high mineral content), you might notice slight chalky residue or faster tip-drying. Some painters use distilled water for consistency, especially when doing competition-level work or airbrush painting where any contamination shows. For regular tabletop painting, don’t overthink it — tap water is fine.

Frequently Asked Questions

What ratio should I thin my paints?

Start with roughly 1:1 paint to water for thick paints like Citadel Base. Thinner paints like Vallejo or Citadel Layer need less — around 2:1 paint to water. The exact ratio varies by paint, age of the pot, and humidity, so test on your palette each time rather than measuring precisely.

Do I need a wet palette?

You don’t need one, but it makes thinning dramatically easier by keeping paint at a workable consistency for hours. A DIY wet palette costs almost nothing to make. It’s strongly recommended for anyone painting regularly.

Why does my thinned paint look patchy?

That’s normal for the first coat. Properly thinned paint is meant to be slightly translucent on the first application. Wait for it to dry fully, then apply a second coat. Two thin coats will give smooth, solid coverage that preserves all detail.

Can I use other liquids to thin paints?

Acrylic medium and flow improver are the main alternatives to water. Some painters use isopropyl alcohol for certain effects, but this is advanced territory. Never use oils, solvents, or household chemicals — they’ll destroy acrylic paint.

How long should I wait between coats?

With properly thinned paint, each coat dries in 5-15 minutes depending on humidity and room temperature. You can test by gently touching an inconspicuous area — if it feels cool or tacky, wait longer. Using a hairdryer on low speed can accelerate drying.

How much should I thin paint for an airbrush?

Much more than for brushwork. Airbrush paint should be roughly the consistency of skimmed milk or thinner, which for thick pots like Citadel Base paints can mean several parts thinner to one part paint. Use a dedicated airbrush thinner or flow improver rather than lots of water, because it keeps the paint bound and reduces tip-drying in the nozzle.

How do I fix a pot of paint that has gone thick?

Add a few drops of clean water or acrylic medium, close the pot and shake or stir it thoroughly, then leave it a few minutes before testing. Repeat until it flows again. Paint that has turned lumpy, rubbery or completely solid can’t be saved and should be replaced. Keeping lids clean and tightly shut slows thickening.

Can I thin Contrast paints?

Yes, but use Contrast Medium rather than water. Contrast Medium thins the paint and makes it more transparent while keeping the flow properties that make Contrast shade into recesses, which is useful for lighter tints and glazes. Water tends to break that effect and leave tide marks. For normal use, apply Contrast straight from the pot.

How to Thin Paints for Miniatures — The Most Important Skill