10 Best Mediums To Thin Acrylic Paint in 2026

A 2.02 oz bottle that works for both airbrush and brush use means you get one thinner for two jobs, and the odorless formula keeps your workspace comfortable. This is the pick for miniature and model painters who need a reliable, predictable thinner that won’t fight their paint’s adhesion or hardness. The bottle is made from r-PET recyclable plastic, and the dilution guidelines are up to 25% for airbrush and up to 50% for brush.

At 60 ml (2.02 fl oz), this bottle is noticeably smaller than many competing thinners, so if you paint frequently you’ll likely need to restock sooner than with a larger container. That compact size makes it easy to tuck into a hobby box or travel kit, and the r-PET recycled plastic bottle keeps the weight down to just 0.2 pounds.

A 250ml bottle of Flow Improver that reduces surface tension, meaning your paint glides smoothly into tight corners and crisp edges without losing any color strength. This makes it the go-to for fine detail work where every brushstroke matters and you need flat, even color without visible ridges. Artists who prize precision and hate fighting drag or skipping paint will appreciate how it keeps the pigment stable from wet to dry, so what you lay down is what you get once it cures.

The biggest reason to buy this medium is that it increases the flow of acrylic colors without changing color strength, so you can lay down flat, even color for hard edge painting techniques. It does slow drying slightly, which means you’ll need to wait longer between layers if you work fast. The no-color-shift promise only holds when you use Winsor & Newton Professional acrylics, so mixing brands could give you different results.

High Flow Medium is GOLDEN’s thinnest acrylic medium, designed to lower viscosity and increase flow and leveling of acrylic colors and mediums. For artists who work with acrylics and need to adjust how their paint behaves, this medium provides control over transparency, viscosity, and surface sheen without altering the color’s basic properties. It is made for professional artists who expect consistency and versatility from their materials.

GOLDEN’s High Flow Medium is their thinnest acrylic medium, designed to extend High Flow Acrylics or lower viscosity while increasing flow and leveling of acrylic colors and mediums. The 4-ounce bottle is compact, so if you are covering large areas or doing heavy pour work, you may go through it quickly compared to larger options like the Winsor & Newton Galeria Acrylic Flow Improver. But for focused studio work where thinning control matters more than volume, this medium delivers exactly what it promises.

An 8.4-ounce jar gives you enough flow improver to cover broad surfaces without constantly refilling, which is exactly what large-scale acrylic work demands. By loosening the surface tension of water inside the paint film, it lets you lay down flat, even color across wide areas while keeping the pigment strength intact. That makes it a natural fit for staining techniques and sweeping washes where consistency matters more than heavy body texture.

The trade-off is that you need to add it sparingly, the instructions say to use only the amount needed for the desired effect, so over-pouring can thin the paint past what you intended. Compared to the Vallejo Airbrush Thinner, which is built for fine spray work, this Galeria improver focuses on brush and flow applications for larger formats. If your priority is covering big canvases or creating fluid stains without shifting hue, this medium delivers exactly that.

A binder-free aqueous solution with surfactants means this isn’t a traditional thinner, it’s a flow aid that breaks water tension and lowers viscosity without adding body. That makes it perfect for staining effects on raw canvas, where paint sinks into fibers for translucent washes. Reviewers note it helps acrylic flow smoothly over absorbent surfaces.

Because it’s binder-free, you can’t rely on it to thicken or build film strength on its own, it’s strictly a flow modifier, not a medium. The Winsor & Newton Professional Flow Improver also reduces surface tension but comes in a 250ml bottle, while this Liquitex option is a 118ml bottle. If you need staining effects on raw canvas, this product is designed for that use; for general-purpose flow improvement, the larger bottle may last longer between refills.

Increasing translucency without reducing color intensity is what this flow medium delivers, making it a straightforward tool for fluid artists. The 250 ml bottle thins acrylic paints and mediums or dilutes binders while keeping vibrancy intact. Reviewers note it enhances flow for pouring or smoother brushwork, giving softer transparency.

This Mont Marte medium focuses on thinning and transparency, as stated in its feature bullets. The trade-off is that you’re getting a straightforward bottle without extra features like drying retarders or gloss control, which some artists might want for precise work. Compared to the Winsor & Newton Professional Flow Improver, which reduces surface tension to improve paint flow and support fine detail, this option is a simple, effective helper for fluid art.

Adding 1-3 drops of this flow improver per 10 drops of paint delays drying and reduces tip dry and nozzle clogging, so you can spray fine details without interruptions. The 200 ml r-PET bottle holds enough for many sessions, and the drop-based dosage lets you mix directly in the airbrush cup. This product is designed for acrylic paints and works with both airbrush and brush, making it a practical choice for miniature and model painters who want to keep their airbrush running smoothly.

For clog prevention, this flow improver directly addresses tip dry and nozzle clogging, as stated in the product features. The trade-off is precision: the drop-based dosage works well for small batches, but if you need exact ratios for larger mixes, a measured thinner like Vallejo’s Airbrush Thinner gives you more control.

The 1:1 mixing ratio with acrylic paint is the key reason this medium makes fluid art approachable for anyone. You don’t need to fiddle with complex formulas or extra tools, just mix equal parts and pour. The clear bottle also lets you see exactly how much is left, so you can plan your next project without guessing. That combination of simplicity and visibility is why this Shuttle Art medium suits artists who want to focus on the pour itself rather than the prep work.

The 250 ml bottle is a standard size for this type of medium, suitable for many fluid art projects. If you work on smaller pieces or occasional projects, the size is fine. For those who need more volume, other brands offer larger containers, but the Shuttle Art’s straightforward mixing and glossy finish make it a practical pick for fluid art newcomers and experienced pourers alike.

This Airbrush Medium combines a thinner and flow improver in a single bottle, so you can adjust thicker acrylic paints to a sprayable consistency while improving their flow through your airbrush. The drop-by-drop method is straightforward: start with one drop of medium, add one or two drops of paint, mix thoroughly, and test on paper before spraying. That process helps you get the right consistency for smooth, controlled coverage on miniatures and models without needing a separate range of airbrush paints.

The 100 ml bottle is a moderate size for hobby use, and the precision dropper bottle keeps dispensing clean and controlled. For miniature painters working on Warhammer armies or D&D figures, it offers a simple way to turn your existing acrylic paints into airbrush-ready colors with less mess.

The 1:4 mixing ratio makes preparation straightforward, but what sets this thinner apart is that it preserves the flexibility of dried acrylic paint. That matters most when you are painting on leather shoes, a fabric jacket, or a canvas bag, surfaces that bend and move. Angelus designed this thinner specifically to keep the paint film from cracking or stiffening, so your work stays durable through wear. It also reduces viscosity for airbrushes, preventing clogs on mesh or cloth, which means finer control on tricky substrates. This is the pick for any project where the painted surface will be handled, folded, or stretched.

The small 4 oz bottle means if you are thinning paint for a large mural or multiple pairs of sneakers, you will need to buy several bottles. Compared to Vallejo Airbrush Thinner, which is also designed for airbrushing but does not emphasize post-drying flexibility, the Angelus wins for wearable or soft-surface art. If your work stays on rigid canvas or models, the Vallejo is a fine alternative. For flexible surfaces, this thinner earns its place.