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Gel Medium

Gel medium is essentially acrylic paint without pigment — the same 100% acrylic polymer binder, colourless and transparent. It is the most versatile and widely used acrylic medium, accounting for nearly 40% of the acrylic medium market. Available in five consistencies (Soft, Regular, Heavy, Extra Heavy, and High Solid) and three finishes (Gloss, Semi-Gloss, Matte) — each combination serving a different purpose. The name refers only to viscosity, not to softness or weight when dry.

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Molding Paste

Molding paste — sometimes called modeling paste — is an opaque, marble-dust or chalk-based medium that builds hard, three-dimensional surfaces. Unlike gel medium which dries transparent, molding paste dries opaque white and can be sanded, carved, drilled, and painted over. It is the primary medium for creating topographical texture and sculptural relief in acrylic painting.

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Pouring Medium

Pouring medium reduces the surface tension of acrylic paint so it flows freely across a surface, self-levels, and dries without the crazing (cracking) that occurs when paint is simply thinned with water. It is the essential medium for fluid acrylic and pour painting. The most reliable professional option is Golden GAC 800, specifically formulated to resist crazing. Liquitex and DecoArt offer mid-market alternatives.

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Retarder Medium

Retarder medium slows the drying time of acrylic paint, extending the open working time from minutes to hours. This allows wet-into-wet blending, soft gradients, and correction — properties that are otherwise unavailable in standard acrylic painting. The critical rule: keep retarder below 15–20% of total paint volume. Exceeding this threshold compromises the integrity of the dried paint film and may prevent proper curing entirely.

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Matte & Gloss Medium

Matte and Gloss mediums modify the final sheen of acrylic paint — the most basic but frequently underestimated control an acrylic painter has over their surface. Acrylic paint is naturally glossy when dry; matte medium brings it to a flat, non-reflective finish. Gloss medium intensifies colour saturation and adds luminosity. Mix the two in any proportion to achieve semi-gloss or satin. Both function simultaneously as paint extenders, flow improvers, and collage adhesives.

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Flow Improver

Flow improver — also called flow aid or flow release — reduces the surface tension of acrylic paint without significantly thinning its colour or binder. A small amount allows paint to spread smoothly and evenly, preventing drag, streaking, and brush marks. It is the essential additive for fine detail work, watercolour-style washes, and any technique requiring clean, even coverage on an absorbent surface.

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Linseed Oil

The most widely used oil medium in painting — and the same binder used in most commercial oil paints. Amber-coloured and pourable like double cream. Increases gloss, transparency, and flow. Slows drying time slightly compared to paint straight from the tube. Dries to a strong, flexible, durable film — one of the most archivally stable binders in painting history. Important limitation: linseed oil yellows over time, particularly in dark or unlit storage. This yellowing bleaches back when the painting is returned to light, but avoid using linseed for whites, pale blues, and delicate flesh tones.

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Stand Oil

Stand oil is linseed oil that has been thickened by heat-polymerisation — historically by leaving linseed oil to stand in sunlight for months, hence the name. The result is a much more viscous oil with exceptional flow-leveling properties. Applied to canvas, stand oil self-levels beautifully, reducing brush marks to a smooth enamel-like surface. It yellows less than regular linseed oil and dries to an extremely durable, flexible film.

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Walnut Oil

The clearest and most colourless of the drying oils — preferred wherever linseed yellowing would be a problem. Walnut oil has been used in painting since at least the Renaissance, particularly for whites, pale blues, and delicate flesh tones. It is non-toxic with a faint, pleasant scent. Dries more slowly than linseed but produces a flexible, moderately strong film. Not as strong as linseed when fully cured — best reserved for upper layers and colours where colour clarity matters most.

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Liquin

Liquin is Winsor & Newton's alkyd resin medium — the most widely used modern oil painting medium in the world. It significantly speeds drying time (touch-dry in 1–3 days versus weeks for straight oil), increases transparency and gloss, and improves flow. It is the preferred medium for glazing, layered indirect painting, and any technique where faster drying between sessions is essential. Important: once you introduce Liquin into a painting, continue with Liquin throughout — do not alternate layers of alkyd and straight oil.

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Turpentine & OMS

Solvents are not mediums in the strict sense — they thin paint and clean brushes rather than modifying its film-forming properties. But they are essential companions to all other oil mediums. Turpentine is the traditional artist solvent — powerful, able to dissolve resins, but strong-smelling and requiring ventilation. Odourless Mineral Spirits (OMS) — with Gamblin's Gamsol as the artist standard — performs the same function with far less fume and is safer for regular studio use. Never use hardware-grade turpentine or white spirit — impurities affect paint films.

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Cold Wax Medium

Cold wax medium is a mixture of beeswax and solvent (typically OMS or turpentine) that thickens oil paint to a stiff, buttery consistency and produces a distinctive matte, velvety surface. It has become increasingly popular as a medium for gestural, layered, and encaustic-influenced abstract work. Cold wax changes not just the texture but the entire character of oil paint — reducing its natural gloss to a waxy, luminous depth that no other medium replicates. Important rule: use cold wax only in upper and final layers. Never use it in underlayers, and never combine with fast-drying alkyd mediums like Liquin.