Why Model Thinners Are Essential for High-Quality Painting

Master the art of paint consistency for flawless finishes on every build

Whether you're working on scale models, miniatures, or architectural models, understanding how to properly thin your paints will transform your finished results. And once you get the hang of it, you'll wonder how you ever managed without them.

Key Takeaways
Primary Purpose	Adjust paint consistency for optimal flow, levelling, and adhesion
Key Benefits	Smoother finishes, better detail retention, reduced brush marks, airbrush compatibility
Main Types	Acrylic (water-based), enamel (solvent-based), lacquer (aggressive solvents)
Typical Ratios	1:1 for brush painting, 1:2 or 1:3 for airbrushing, varies by brand
Application Methods	Brush painting, airbrushing, glazing, weathering techniques

Model Thinners at a Glance

Right, so you've got yourself a lovely new gundam kit or maybe a beautiful aircraft model, and you're thinking about painting it. You grab your acrylic paints, load up your brush, and... well, the paint's a bit thick, isn't it? Goes on like treacle, leaves brush marks everywhere, and generally makes your detailed work look a right mess.

This is where model thinners come into play - and honestly, they're one of those things that separate the casual painters from the folks who get those jaw-dropping finishes you see online. Think of it this way: you wouldn't put neat cordial in a glass and expect it to be pleasant, would you? Paint's much the same - it needs the right consistency to perform properly.

What exactly are model thinners, then? They're specially formulated liquids designed to adjust paint consistency whilst keeping all the good stuff - the pigments, binders, and additives - working together harmoniously. Unlike chucking some water into your Vallejo paints (which works, sort of, but isn't ideal), proper thinners maintain the paint's integrity whilst improving how it flows and levels on your model's surface.

The real magic happens when you start using airbrushes. Try spraying unthinned paint through one of those delicate nozzles and you'll quickly understand why thinners exist - it's like trying to drink a thick shake through a coffee stirrer. Your airbrush will clog faster than a drain in a share house, and you'll spend more time cleaning than painting.

Different paint types need their own specific thinners, too. Your enamel paints won't play nicely with acrylic thinners, and lacquers are in a league of their own entirely. Get this wrong and you'll end up with something that looks like cottage cheese rather than a smooth paint finish.

What Are Model Thinners?

Model thinners are specially formulated liquids designed to adjust the consistency of paint used in scale modelling and miniatures. Unlike plain water or household solvents, proper thinners maintain pigment integrity whilst improving flow, levelling, and adhesion. They're essential for achieving precision—especially when working with airbrushes or applying multiple thin coats on finely detailed surfaces.

The chemistry behind quality thinners is actually quite fascinating, though you don't need a science degree to use them effectively. Manufacturers like Tamiya and Vallejo spend considerable time formulating thinners that not only reduce viscosity but also enhance the paint's performance characteristics. These aren't just dilutants - they're performance enhancers for your paint collection.

Depending on the paint type—whether you're using acrylics, enamels, or lacquers—different thinners are required to ensure compatibility and performance. Using the wrong thinner can result in clumping, separation, or complete surface failure. I've seen modellers ruin entire Gunpla kits by mixing incompatible products, and it's heartbreaking every time.

The key difference between model thinners and generic solvents lies in their formulation. Quality thinners contain flow improvers, retarders (which slow drying time), and sometimes anti-foaming agents. When you're working on detailed miniatures or intricate aircraft models, these additives make the difference between amateur and professional-looking results.

Why Thinners Matter for Your Models

Thinners aren't just for dilution—they actively improve how paint behaves on your model's surface. The science of surface tension and flow dynamics might sound intimidating, but the practical benefits are immediately apparent once you start using quality thinners with your model paints.

Flow and Levelling: Thinners reduce surface tension, helping paint spread more evenly across plastic or primed surfaces. This is particularly crucial when working with primer or when applying base coats to large areas. Without proper thinning, paint tends to sit on the surface rather than flowing into the microscopic texture of the material.

Detail Retention: Thin paint clings lightly to detail rather than pooling or burying surface texture—ideal for scale models with engraved panel lines or raised details. Thick paint acts like a liquid blanket, obscuring the very details you want to highlight.

Controlled Drying: Especially with Tamiya acrylics and Vallejo mediums, proprietary thinners offer better drying times for layer blending and edge highlighting. This controlled drying prevents the dreaded "orange peel" texture that occurs when paint dries too quickly.

High-end modellers prefer thinners not just for effect—but for consistency. When you're working on a competition-level diorama or a showcase military model, every coat needs to perform identically. Properly thinned paint results in fewer brush strokes, smoother finishes, and greater visual impact that'll make your mates wonder how you managed such professional results.

The working time extension that quality thinners provide cannot be overstated. When applying washes or glazes using weathering products, you need time to manipulate the paint before it sets. Generic thinners often evaporate too quickly, leaving you with patchy, uneven coverage.

Choosing the Right Thinner for Your Paint System

Here's where many modellers get themselves into trouble - assuming all thinners are created equal. The compatibility between your paint and thinner isn't just important, it's absolutely critical for success. Get this wrong and you'll be stripping paint rather than applying it.

Paint Type	Recommended Thinner	Best Applications	Browse Options
Acrylic	Water-based acrylic thinner (Tamiya X-20A, Vallejo Airbrush Thinner)	General painting, airbrushing, weathering	View Acrylics
Enamel	Mineral spirits or Humbrol Enamel Thinner	Detail painting, panel lining, washes	View Enamels
Lacquer	Strong volatile thinner (Tamiya Lacquer Thinner)	Base coats, primer, automotive finishes	View Lacquers

Acrylic thinners are the most beginner-friendly option. They're water-based, have minimal odour, and work brilliantly with the vast majority of hobby paints available today. Most Citadel paints and Vallejo Game Color respond beautifully to their respective brand thinners, though cross-compatibility is generally good within the acrylic family.

Enamel thinners pack more punch and require better ventilation. They're slower-drying, which makes them perfect for blending and weathering effects on military vehicles or ships. The extended working time allows for sophisticated techniques like pin washes and realistic rust effects.

Lacquer thinners are the heavy-duty option. They're aggressive, fast-drying, and create incredibly durable finishes. If you're serious about automotive scale models or want that glass-smooth finish on your custom builds, lacquers thinned properly will give you results that rival commercial paint jobs.

Choosing the right thinner for your paint system is crucial. Browse our full thinners collection to get compatible solutions that'll work harmoniously with your existing paint supplies. Don't mix and match randomly - compatibility charts exist for good reason.

How to Use Thinners Correctly

Getting the ratio right is part science, part art, and entirely dependent on what you're trying to achieve. There's no universal "correct" ratio because different techniques require different consistencies. However, there are some reliable starting points that'll save you from making costly mistakes on your prized collector models.

Start with a 1:1 ratio of paint to thinner for general brush painting, then adjust based on the effect you're aiming for. This ratio works well for most acrylic hobby paints and gives you a consistency that flows nicely without being too runny. For glazes and weathering washes, you might push this to 1:3 or even 1:4, but that's advanced territory.

Mix thoroughly—inconsistent blends cause clogging in airbrushes or streaks in brushwork. I use a cocktail stick for small amounts or invest in proper mixing tools for larger batches. The paint and thinner should be completely homogeneous before application.

Apply in layers—thin coats dry faster and build up smoother, more even colour. This is particularly important when painting white metal miniatures or working with light colours over dark primers. Two thin coats always beat one thick coat.

Test on scrap plastic before applying directly to your model. Every combination of paint, thinner, and surface behaves slightly differently. Keep some spare plastic sheets or failed kit parts for testing. This simple step prevents disasters on expensive limited edition kits.

Advanced technique: Temperature matters. Warm thinners flow better and mix more easily, whilst cold thinners can cause the paint to break or separate. Room temperature is usually perfect, but in winter months, letting your paint bottles warm up to room temperature before mixing can prevent frustrating compatibility issues.

Storage and mixing: Always use a mixing cup or palette rather than pre-thinning paint in the original containers. Pre-thinning paint in jars can cause premature ageing and pigment separation. Those little mixing cups might seem like an unnecessary expense, but they'll save you money in the long run by preventing waste.

For airbrush work, strain your thinned paint through a fine mesh or old stocking material. Even tiny particles can clog your airbrush's delicate internals, leading to expensive repairs or replacement of airbrush parts.

Common Mistakes to Avoid

Even experienced modellers can fall into these traps, and beginners almost always make at least one of these errors during their learning journey. Learning from others' mistakes is cheaper than ruining your own premium model kits.

Over-thinning: Paint turns translucent or fails to adhere properly. This is particularly problematic with metallic paints where the metal flakes need sufficient binder to stay suspended. Avoid exceeding a 1:3 ratio unless you're specifically doing glazes or washes. Over-thinned paint often requires multiple coats to achieve proper coverage, negating the time-saving benefits.

Wrong thinner: Using enamel thinner in acrylics equals instant paint shock - the paint will curdle, separate, or become grainy. Always use the correct thinner for your paint type. This seems obvious, but it's easy to grab the wrong bottle when you're in the zone painting your latest project.

Skipping primer: Without a properly primed surface, thinned paint beads up or flakes off. This is especially problematic on smooth plastic surfaces or metal miniatures. Always prime your models first using quality primer products. The primer creates a uniform surface that accepts thinned paint consistently.

Mixing incompatible brands: Whilst most acrylics play nicely together, mixing Vallejo thinners with Citadel paints or vice versa can sometimes cause unexpected reactions. When in doubt, stick with matching brand systems or test thoroughly first.

Poor workspace ventilation: Even water-based thinners can cause headaches in poorly ventilated spaces. Enamel and lacquer thinners require proper ventilation and may need respiratory protection. Don't underestimate the importance of a safe working environment.

Not accounting for humidity: High humidity can prevent thinned paint from drying properly, leading to a tacky finish that never fully cures. Low humidity can cause paint to dry too quickly, preventing proper flow and levelling. Australian weather can be particularly challenging - adjust your thinning ratios based on conditions.

Explore our paint and surface preparation range to make sure you're starting with the right foundation. Remember, successful model painting is about building good habits and understanding your materials rather than rushing through the process.