Color is often the first feature that draws us into a painting, but in art history and conservation it is far more than a visual impression. Color can offer important clues about how a work was created, the choices an artist made and the ways it may have changed over time.
For art conservators and those caring for historic oil paintings, understanding the use of color, pigments and materials is essential for historical context, professional restoration and long-term preservation.
Above: detail from Oleanders by Vincent van Gogh, 1888
What Is Oil Paint Made Of?
Traditional oil paint is made from two main components:
Pigment: the substance that provides color
Drying oil: the binder that turns pigment powder into paint
Pigments can come from many sources, including minerals, metals, natural earths such as ochre, plants, animal materials or modern synthetic compounds. To create paint, these pigments are mixed with oils, most commonly linseed. As the paint dries, the oil forms a flexible film that holds the pigment particles together and allows the paint to adhere to the surface.
Oil paints may also contain additional ingredients such as natural resins, waxes, or drying agents that influence texture, gloss, or drying time. Before the 19th century, artists usually prepared their own paints by grinding pigments and mixing them with oil. Because of this handmade process, paint mixtures could vary widely from one artist to another, which can affect how a painting ages.
How Was Color Used Across Art History?
For much of art history, artists worked closely with the physical materials that produced color. Preparing pigments and mixing paints meant that painters had a deep understanding of how their colors behaved, how they blended, dried, and changed when layered.
During the Renaissance, artists such as Leonardo da Vinci began studying color more scientifically, observing how light, shadow and atmosphere affect the way colors appear. These observations helped painters create greater realism through subtle changes in tone and color temperature – think warm reds and cool blues.
Above: detail from The Interior of a Woman Painter’s Studio by Marie Victoire Lemoine, 1789
By the 19th century, scientific discoveries in optics led to the development of tools such as the color wheel, helping artists understand how colors interact through contrast and harmony. At the same time, industrial production introduced many new, easily accessible pigments, including chrome yellow, cobalt blue and emerald green. While these pigments offered new creative possibilities, some proved chemically unstable and have changed over time. For conservators today, identifying historical pigments can reveal important information about a painting’s age, materials and techniques.
Above: detail from In the Studio by Alfred Stevens, 1888
How Much Artistic Freedom Did Historic Artists Have?
Color was both a technical tool and an economic consideration. Pigments varied dramatically in price, availability and quality. Some colors were made from common earth minerals and were relatively affordable. Others came from rare materials that were expensive to obtain and process.
One of the most famous examples is ultramarine blue, historically made from the semi-precious stone lapis lazuli imported from Afghanistan. It was so costly that it was often reserved for the most important parts of a painting, such as the robes of the Virgin Mary. Patrons sometimes specified in contracts how much of a particular pigment should be used, because they were effectively paying for the material as well as the artist’s labor.
Above: detail from Madonna and Child by Titian, 1508
This balance between commerce and artistic freedom shaped how painters approached color. Artists had to think carefully about how to achieve visual richness while working within the financial limits of a commission. Some developed highly skilled techniques to extend small amounts of expensive pigments through glazing or mixing, while others relied on more affordable earth colors to build complex palettes.
When colours became more easily obtainable in the industrial revolution of the 19th century, artists were able to practice with more freedom – without the constraints of traditional patronage and expensive materials.
Above: detail from Haystacks, Morning, Eragny by Camille Pissarro, 1899
Why Do Paintings Change Over Time?
The colors in oil paintings can change due to natural aging and environmental conditions. Several factors contribute to these changes:
Light: prolonged exposure can cause certain pigments to fade
Environment: fluctuations in temperature or humidity can affect paint layers
Pollution: airborne contaminants may react with pigments or varnish
Varnish: varnish often yellows over time, making paintings appear darker
Binders: drying oils become more transparent as they age, altering how underlying colors appear
Some pigments are also naturally unstable. Certain yellows may darken, reds can fade in strong light, and copper-based greens may change color as they oxidize. Understanding these processes helps conservators interpret how a painting may have originally looked.
Above: our conservator assessing pigments under UV light
Understanding Color in Art Conservation & Care
When restoring a painting, conservators rely heavily on their understanding of color. The goal of conservation is not to repaint the artwork but to stabilize it and integrate restoration work so it blends visually with the original paint while remaining reversible.
To achieve this, conservators study:
The artist’s layering and mixing techniques
How pigments have aged
How varnish and lighting affect the painting’s appearance
Even small retouching areas require precise color matching. Conservators must consider how new conservation pigments will appear once varnish is applied and the painting is viewed under normal lighting conditions.
Preserving Color
The colors we see in historic oil paintings are the result of centuries of artistic experimentation, material choices, and natural aging.
By studying pigments, materials, and color relationships, conservators can better understand how paintings were originally created and how they have changed over time.
This knowledge allows conservation professionals to preserve artworks more accurately, ensuring that the colors chosen by artists can continue to be appreciated for generations to come.
Above: contemporary art and historic paintings both require care when it comes to preserving their true colors
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