Demystifying Oil Painting Mediums: A Guide to Linseed, Walnut, Spike Lavender, and Alkyd

Unlike acrylic paint, which dries simply through water evaporation, oil paint dries through oxidation—a

chemical reaction where the drying oil absorbs oxygen and solidifies into a durable film. Oil paint mediums are liquid additives used to alter this drying time, change the paint’s viscosity (thickness), adjust the gloss level, or increase transparency.

Understanding these mediums is the key to mastering your paint's behavior. This guide explores four of the most popular and useful oil painting mediums: linseed oil, walnut oil, spike lavender oil, and alkyd media.

1. Linseed Oil: The Traditional Standard

Linseed oil, pressed from the seeds of the flax plant (Linum usitatissimum), is the historical backbone of oil painting. It is the most widely used binder and medium in the art world.

Varieties of Linseed Oil

• Refined Linseed Oil: The standard, general-purpose medium. It lowers paint viscosity, slows drying time, and increases gloss and transparency.

• Cold-Pressed Linseed Oil: Extracted without heat, this oil is considered pure and highly durable. It improves paint flow and is favored by traditionalists for hand-grinding pigments.

• Stand Oil: Linseed oil that has been heated in an oxygen-free environment. It becomes thick, honey-like, and highly viscous. Stand oil levels out brushstrokes, dries to a smooth, enamel-like, high-gloss finish, and is highly resistant to yellowing.

Properties & Best Uses

• Drying Time: Medium (typically dries to the touch in 3 to 6 days depending on application thickness).

• Gloss Level: High gloss.

• Yellowing: Moderate. Linseed oil naturally yellows over time, especially when kept in dark environments (though exposure to natural light can reverse this effect).

• Best For: Creating smooth glazes, increasing paint flow, and building durable paint layers in the middle-to-late stages of a painting.

2. Walnut Oil: The Luminous Alternative

Walnut oil has been used as an artistic medium since the Renaissance. Highly favored by masters like Leonardo da Vinci, it offers a natural, slow-drying alternative to linseed oil.

Properties & Best Uses

• Drying Time: Slow (dries slower than refined linseed oil, often taking 5 to 9 days).

• Gloss Level: Medium-high gloss.

• Yellowing: Low. This is walnut oil’s greatest strength; it yellows significantly less than linseed oil over time.

• Best For: Painting with whites, pale blues, and light pastel colors where yellowing would be highly noticeable. It is also excellent for wet-on-wet (alla prima) painting due to its extended working time.

Pros and Cons

• Pros: Highly fluid, reduces paint viscosity smoothly, resists yellowing, and is entirely natural and non-toxic.

• Cons: Dries slowly, which can test the patience of artists working on tight deadlines. It also forms a slightly less rigid paint film than linseed oil, though it remains highly durable for archival standards.

3. Spike Lavender Oil: The Natural Solvent

Unlike linseed and walnut oils, which are fatty binders, Spike Lavender Oil (distilled from Lavandula latifolia) is a natural solvent. It is used to thin oil paints and mediums rather than fatten them.

Historically used by artists like Peter Paul Rubens, spike lavender oil has experienced a modern resurgence as a safer, natural alternative to harsh petroleum-based solvents like odorless mineral spirits (OMS) or turpentine.

Properties & Best Uses

• Drying Time: Fast. Because it evaporates, it speeds up the initial drying time of the paint.

• Gloss Level: Matte to satin (solvents disperse the oil binder, resulting in a less glossy finish).

• Toxicity & Scent: Non-hazardous but highly aromatic. It has a powerful lavender scent. While it does not produce the toxic petroleum vapors of mineral spirits, the intense fragrance still requires a well-ventilated studio.

• Best For: Thinning paint for the initial underpainting (the "lean" layer), cleaning brushes, and thinning thick oil mediums.

Pros and Cons

• Pros: Strong solvent power (can dissolve resins easily), pleasant natural aroma, safer for artists with chemical sensitivities to petroleum solvents.

• Cons: Highly volatile; the strong scent can become overwhelming in small, unventilated spaces. It is also significantly more expensive than standard mineral spirits.

4. Alkyd Mediums: The Modern Speed-Driers

Alkyd mediums are a modern addition to the artist’s toolkit. They are made from synthetic polyester resins modified with natural drying oils (such as soy or linseed oil) and a small amount of solvent. The most famous commercial example is Winsor & Newton’s Liquin.

Properties & Best Uses

• Drying Time: Very fast. Alkyd mediums typically dry to the touch within 12 to 24 hours.

• Gloss Level: Varies from semi-gloss to high-gloss depending on the specific formulation (e.g., gel vs. liquid).

• Viscosity: Available in various forms, from self-leveling liquids to buttery gels that retain brush marks.

• Best For: Artists working on tight deadlines, glazing techniques, and underpaintings where a dry surface is needed the next day.

Pros and Cons

• Pros: Dramatically speeds up drying times, resists yellowing, levels out brushstrokes nicely, and creates a tough, flexible, and uniform paint film.

• Cons: Contains solvents (requiring proper ventilation), dries too quickly for artists who prefer to blend paint on the canvas over several days, and can feel slightly "gummy" if overused.

Studio Safety and Care

• Spontaneous Combustion: Rags soaked in drying oils (especially linseed oil) generate heat as they oxidize. Never leave oil-soaked rags bunched up. Lay them flat on a non-combustible surface to dry, or submerge them in water before disposing of them.

• Ventilation: Even natural solvents like spike lavender oil release volatile organic compounds (VOCs). Ensure your workspace has a steady cross-breeze of fresh air.

• Less is More: Always use mediums sparingly. Over-diluting paint with solvent can break down the binder, causing the paint to dry chalky and flake off. Overusing oil can result in a wrinkly, sticky surface that takes years to fully cure.

Many artists find that a single medium is too extreme. You can mix your own custom medium by blending oils and solvents.

By understanding the unique chemistry of these mediums, you gain total control over your artistic process, allowing you to paint with confidence and create pieces that will endure for generations.