The Artist's Guide to Oil Painting - Choosing the Right Oil

From ancient cultivation practices to contemporary studios, the oils that bind our pigments carry stories of human ingenuity, agricultural mastery, and artistic evolution spanning millennia.

Oil painting has captivated artists for over a thousand years, offering unparalleled richness, depth, and working time that watercolour and tempera cannot match. But beneath the surface of every masterpiece lies a crucial decision: which oil to use as a binder. The choice between linseed, walnut, poppy, and safflower oils has a profound impact not only on how paint behaves on canvas but also on how it ages over centuries.

While many contemporary artists rely exclusively on commercial tube paints, understanding the properties and origins of painting oils—and learning to create your own paints—opens up new dimensions of artistic control and connects you directly to the traditions practised by Leonardo, Vermeer, and countless other masters throughout history.

Oil painting emerged in the medieval period when artists discovered that mixing finely ground pigments with drying oils created paints with unprecedented versatility and durability. Archaeological evidence from caves behind the destroyed Buddhas in Bamiyan suggests oil painting techniques were used as early as the 7th century, possibly predating European developments by centuries. However, it was in 15th-century Northern Europe that oil techniques truly flourished, with masters like Jan van Eyck perfecting methods that would define painting for generations.

The success of oil painting lies in the unique chemistry of drying oils. Unlike non-drying oils found in your kitchen, painting oils contain high levels of unsaturated fatty acids that undergo polymerisation when exposed to oxygen. This process, called autoxidation, transforms liquid oil into a flexible, durable film that can last centuries while remaining slightly workable for hours or even days.

Cultivation and Origins

Linseed oil comes from flax (Linum usitatissimum), one of humanity's earliest domesticated crops. Originally domesticated in the Fertile Crescent, flax has been cultivated since 3000 B.C.E., making it one of the earliest domesticated plants. The Latin name "usitatissimum" translates to "most useful," reflecting its dual purpose for both fibre production (linen) and oil extraction.

Today's major flax-producing regions include Canada, Russia, and Kazakhstan, with France producing 75% of the world's supply of flax. The plants grow 2-4 feet tall with delicate blue flowers that open each morning and shed their petals by afternoon after self-pollinating. Seeds develop in small capsules that rattle when mature, signalling harvest time.

Extraction and Processing

Traditional linseed oil extraction involves crushing the seeds and pressing them to release their oil. Ancient Egyptians used two primary methods: decanting (where hot water was poured over crushed seeds and oil was scooped off the surface) and pressing (squeezing oil directly from seeds). Modern processing offers three approaches:

Cold pressing preserves the oil's natural properties by extracting without heat, yielding the purest oil for artistic use. Hot pressing increases yield but may alter the oil's characteristics through heat exposure. Solvent extraction using hexane maximises oil recovery but requires extensive refining to remove chemical residues, making it suitable only for industrial applications.

Properties and Characteristics

Linseed oil has the strongest film of any oil used in painting, making it less likely to crack. It also dries relatively fast for an oil, becoming touch dry in a few days and curing fully in about 6 months. This strength comes from its high linolenic acid content, which promotes cross-linking during the drying process.

However, this same linolenic acid causes linseed oil's primary drawback: yellowing over time. The pale yellow colour becomes more pronounced in dark storage, but fortunately bleaches back to clear when exposed to light for just a few days.

Pros:

• Strongest, most durable paint film
• Relatively fast drying (3-5 days touch dry)
• Excellent pigment suspension
• Widely available and affordable
• 600+ year proven track record

Cons:

• Yellowing tendency, especially in dark storage
• Strong odor
• Can become brittle over extremely long periods

Cultivation and Origins

Walnut oil derives from the common walnut (Juglans regia), cultivated across temperate regions worldwide. Unlike flax, which requires specific growing conditions, walnut trees adapt to diverse climates and can produce nuts for decades. Major producing regions include California, France, and parts of Eastern Europe and Asia.

The extraction process mirrors that of linseed oil—nuts are cracked, cleaned, and either cold-pressed for artist-grade oil or processed with heat and solvents for lower grades. Leonardo da Vinci was particularly concerned with extraction methods, noting that walnut skins could discolour the oil if not removed during pressing.

Historical Significance

Walnut oil was known to the Egyptians in the fifth century, and by the Renaissance had become the preferred medium for many masters. Giorgio Vasari wrote that artists should "grind the colours with walnut or linseed oil, though walnut oil is better because it yellows less".

Vermeer's use of walnut oil is well documented. He sometimes used linseed oil in darker passages where yellowing wasn't problematic, but stayed with walnut oil for lighter colours. Other notable users included Van Eyck, Van Dyke, Raphael, and Rubens, who studied Italian mediums during his nine-year stay in Italy and made improvements to traditional techniques.

Properties and Characteristics

Walnut oil resists yellowing and cracking according to M. Graham & Co., and can be used to remove colour from artists' tools as effectively as odourless paint thinners. The oil enhances paint flow, creating smooth applications with enhanced colour brilliance.

Walnut oil is a light, pale yellow oil that dries slowly, producing a flexible and durable film. It is often used as a substitute for linseed oil, as it has a less pronounced initial yellow hue, and some claim it does not yellow as much over time.

Pros:

• Minimal yellowing compared to linseed oil (due to its lower linolenic acid content, which reduces the risk of yellowing over time)
• Excellent colour retention for whites and blues
• Smooth application and enhanced paint flow
• Can double as a brush cleaner
• Pleasant, mild odour

Cons:

• Slower drying time than linseed oil
• More expensive than linseed oil
• Can turn rancid if not stored properly (refrigeration recommended)
• Weaker paint film than linseed oil

Cultivation and Origins

Poppyseed oil is obtained from poppy seeds (specifically seeds of Papaver somniferum, the opium poppy). Poppy seeds yield 45–50% oil. Despite its association with opium poppies, the oil has no narcotic properties and is highly palatable, high in vitamin E.

An early 20th-century industry manual states that while the opium poppy was grown extensively in Eurasia, most of the world's production of poppyseed oil occurred in France and Germany. Unlike flax and walnuts, large-scale poppy cultivation for oil is a relatively recent development, primarily emerging in the 19th and 20th centuries.

Properties and Characteristics

Poppyseed oil dries much more slowly (5–7 days) than linseed oil (3–5 days). For this reason, poppyseed oil should not be used for a ground layer of a painting, and linseed oil should not be painted over a layer of poppyseed oil.

Poppy seed oil is a pale yellow oil that dries slowly, producing a flexible and  durable film. It is often used in the final layers of a painting as it allows for more time to blend and work with the paint. Poppy seed oil is also known for its ability to enhance the brightness of pigments.

Pros:

• Minimal yellowing, excellent for whites and pale colors
• Very slow drying allows extended working time.
• Enhances pigment brightness
• Pleasant texture and handling

Cons:

• Very slow drying (5-7 days minimum)
• Weaker paint film than linseed or walnut oil
• Cannot be used in underpainting layers
• More expensive than linseed oil
• Limited availability

Safflower oil was introduced into painting in the mid-twentieth century and was unknown to earlier artists. Derived from safflower plants (Carthamus tinctorius), this oil offers properties similar to those of poppy oil, colourless but with better availability and lower cost.

Safflower oil is a light, nearly colourless oil that dries the slowest of all the drying oils used by artists and produces a flexible film. It is often used as a substitute for linseed oil when increased drying time is desired.

Pros:

• Minimal yellowing
• Nearly colorless
• Suitable colours for whites and pale colors
• More affordable than poppy oil

Cons:

• Very slow drying
• Weaker paint film
• Limited historical testing
• May have long-term stability issues

Creating your own oil paints offers complete control over pigment quality, oil choice, and paint consistency while connecting you to centuries of artistic tradition. The process requires patience but rewards you with paint perfectly suited to your specific needs.

Grinding surface: A glass slab with an etched surface provides the ideal grinding platform. You can create your own by grinding silicon carbide on glass with a muller.

Muller: A heavy, flat-bottomed glass tool used to grind pigment into oil. Get the heaviest muller possible—weight helps you grind without applying excessive downward pressure.

Palette knife: For mixing and testing paint consistency.

Pigments: High-quality artist pigments from reputable suppliers.

Safety equipment: Dust mask, gloves, and eye protection when handling dry pigments.

1. Prepare your workspace: Ensure good ventilation and lay out all materials. All fine powders are dangerous to breathe in. Scoop pigment from containers rather than pouring to minimize airborne particles.
    
2. Initial mixing: Place a small amount of pigment on your glass slab and add oil drop by drop, mixing with a palette knife until you achieve a paste-like consistency.
    
3. Test consistency: For the peak test, press the knife flat into your paste and lift straight up. Perfect consistency produces peaks that stand up without flopping over.
    
4. Grinding: Using a glass muller, rub the paste in circular motions, spreading it into thin layers. This process coats every particle of pigment with oil and can take anywhere from a few minutes to several hours depending on the pigment.
    
5. Final adjustments: Add more oil if the paint appears dry and cracked, or more pigment if it's too runny.
    

Each pigment requires different proportions to maximize its potential. Published charts detailing oil absorption rates are not always reliable because pigments from different sources have varying compositions.

Generally, start with a 1:1 ratio of pigment to oil by volume and adjust based on the specific pigment's behavior. Ultramarine Blue with linseed oil typically requires about a 3:4 ratio (oil to pigment), while with poppy oil it needs a higher proportion of oil.

Ultramarine Blue: One of the more difficult pigments to disperse in oil. It may not wet easily at first, then suddenly becomes soft and fluid. If this happens, set it aside for a week in a closed container, then grind further.

Heavy pigments (like Vermilion): The problem with heavy inorganic pigments is separation from binder. Consider using a mixture of regular oil and stand oil (thickened linseed oil) to prevent separation.

White pigments: Best made with walnut, poppy, or safflower oil to avoid yellowing.

The choice of oil depends on your painting technique, subject matter, and personal preferences:

For traditional alla prima painting: Linseed oil provides the best balance of working time and film strength.

For indirect painting with multiple layers: Use linseed oil for dark colors and underpainting, walnut oil for light colors and detailed work.

For extended blending time: Poppy or safflower oil in final layers allows prolonged manipulation.

For portrait work: Walnut oil in flesh tones prevents yellowing that could alter skin color over time.

For landscape painting: Linseed oil throughout provides durability for outdoor subjects.

The evolution of painting oils reflects broader patterns of trade, agriculture, and technological development. Research into historical recipes shows that painters in the North preferred linseed oil, whereas in the South, particularly in Italy, walnut oil seems to have been more common.

This regional preference likely reflected both agricultural conditions and artistic traditions. Northern European artists, working in cooler climates where flax thrived, developed techniques that exploited linseed oil's fast drying and strong film. Italian Renaissance masters, with access to abundant walnut groves and working in warmer studios, perfected the use of walnut oil for its superior color retention and refined handling qualities.

The choice of oil became part of each artist's signature technique. Rembrandt is credited with using a thickened walnut oil and sometimes a resin to enhance the flow of the paint, contributing to his distinctive impasto effects and luminous glazes.

Understanding how painting oils dry helps explain their different properties and applications. Drying oils undergo autoxidation—the absorption of oxygen at room temperature, leading to formation of hydroperoxides that decompose into various radicals. These radicals react through oligomerization, where small molecular units bond to form larger, more complex structures.

The speed and completeness of this process depend on the oil's fatty acid composition. Linolenic acid promotes faster, more complete polymerization but also contributes to yellowing. Oils with primarily linoleic acid (like safflower and poppy) dry more slowly and yellow less but form weaker films.

Modern artists increasingly consider the environmental impact of their materials. Linseed oil production generally has a lower environmental footprint than synthetic alternatives, as flax requires fewer inputs than many crops and the entire plant can be utilized—seeds for oil, stems for fiber.

Walnut oil production supports orchard agriculture that provides habitat for wildlife and can be part of sustainable farming systems. However, water requirements for walnut cultivation in drought-prone regions raise environmental concerns.

Poppy cultivation for oil is often integrated with pharmaceutical production, making it an efficient use of agricultural resources.

As artists and manufacturers seek alternatives to petroleum-based products, traditional painting oils are experiencing renewed interest. Modern processing techniques can produce oils with improved clarity and reduced yellowing while maintaining the working properties that have made them indispensable for centuries.

Research into oil modification—including stand oil production and the addition of natural antioxidants—continues to refine these ancient materials for contemporary use. Some manufacturers are developing hybrid approaches that combine traditional cold-pressing with modern filtration and stabilization techniques.

The oils we choose as vehicles for our pigments carry within them the accumulated wisdom of millennia of human cultivation, processing, and artistic experimentation. Whether you work with linseed oil for its proven durability, walnut oil for its luminous clarity, or poppy oil for its extended working time, you participate in traditions that connect your studio to ancient Egypt, Renaissance Italy, and countless other moments when artists mixed pigment with oil and created beauty that endures.

Making your own paints deepens this connection, offering not just economic advantages and artistic control but also the meditative satisfaction of creating your medium from fundamental materials. In an age of industrial art supplies, this hands-on approach reminds us that painting remains, at its heart, a craft—one that transforms simple elements through knowledge, skill, and vision into works that speak across centuries.

The choice of oil is never merely technical; it's part of your artistic voice, influencing how your work will look today and how it will age over time. By understanding these materials—their origins in field and orchard, their processing from seed to studio, and their behavior on canvas—you make more informed decisions that serve both your immediate artistic goals and your work's legacy.

As you stand before your canvas with brush loaded with paint, remember that you hold in your hand a medium that has served artists for over a thousand years and will likely serve them for a thousand more. The oil that binds your pigments carries not just color to canvas, but the continuity of human expression itself.