In 2013, a painting by the Dutch CoBrA artist Karel Appel began to develop small, raised blisters across its surface. The blisters were zinc soap formations: zinc oxide pigment reacting with the fatty acids in the oil binder to create crystalline zinc carboxylates that push through the paint film. The painting was 60 years old, and the zinc white that had been mixed into its colors was slowly destroying it from within. This is the paradox of zinc white. It was introduced in the late 18th century as a safe, non-toxic replacement for lead white, and it did make painters' studios less dangerous. But it introduced a new problem that conservators are still struggling to solve: zinc white reacts with oil paint binders in ways that cause the paint film to crack, delaminate, and form soap inclusions that can take decades to appear.
Zinc white is a white pigment composed of zinc oxide (ZnO). It is semi-transparent, meaning it has less covering power than lead white or titanium white, and it produces a cooler, cleaner white when used pure. The pigment was developed in the late 18th century as a non-toxic alternative to lead white and entered commercial production in the 1840s. It was widely used in 19th and 20th-century painting, both as a mixing white and as a component of commercial paints, but its tendency to form zinc soaps in oil paint has made it a major conservation concern for modern collections.
This entry covers the history of zinc white, its properties, why it was adopted and then partially abandoned, and the conservation challenges it poses in 20th-century artworks.
What Is Zinc White and How Is It Made?
Zinc white is zinc oxide, a compound that has been known since ancient times but was not produced as a pigment until the late 18th century. The pigment is manufactured through one of two pyrometallurgical processes. The indirect (French) process involves heating metallic zinc until it vaporizes, then allowing the zinc vapor to oxidize in air to form zinc oxide particles. The direct (American) process involves smelting zinc ore directly in a furnace, producing zinc oxide along with impurities from the ore. The indirect process produces purer, finer pigment, while the direct process is cheaper but yields a product with more contaminants, including lead in some historical samples.
A 2023 study published in Heritage Science by researchers at the University of Amsterdam conducted the first systematic survey of a large corpus of zinc white artist materials, analyzing 49 samples from historical and modern pigment powders and paint materials from leading European and American manufacturers. The study found that indirect-process zinc oxide, characterized by submicron prismoidal particles with blue luminescence, was the dominant type in artist materials. The researchers also identified hydrozincite, a zinc carbonate mineral, in several samples, likely a degradation product of the zinc oxide. Read the study at Springer Nature Link.
The key property that distinguishes zinc white from lead white and titanium white is its transparency. Zinc oxide has a lower refractive index than either lead carbonate or titanium dioxide, which means it scatters less light and produces a more translucent paint film. This makes zinc white less useful for opaque highlights but excellent for modifying the transparency of other colors. Painters who wanted to lighten a color without making it chalky and opaque often chose zinc white over lead white for this reason.
Origins and History
Zinc oxide was known to ancient alchemists, but its use as a pigment began in France in the 1780s, when concerns about the toxicity of lead white in house paint and cosmetics drove the search for alternatives. The French court was particularly motivated: lead-based cosmetics had caused well-documented health problems among aristocratic women, and the pigment was also dangerous for the workers who manufactured it. Commercial production of zinc white began in the 1840s, with the Vieille Montagne company in Belgium becoming a major supplier.
In the United States, direct-process zinc oxide was developed in 1852 to take advantage of large zinc ore deposits in New Jersey. American production was cheaper but produced a less pure pigment. Some American zinc white contained significant amounts of lead, up to 35% basic lead sulfate in some samples, because the ore was not fully separated before processing. This "leaded zinc" was used primarily in commercial house paint rather than artist materials, but it complicates the analysis of 20th-century paintings that may contain both pigments.
A 2024 doctoral dissertation from the University of Florence by Cecilia Gallai explored the physico-chemical properties of 19th and 20th-century zinc white paints using a multidimensional approach, from nano- and microscopic analysis to macroscopic study of artworks. The research, which analyzed approximately 50 paintings in-situ at museums, found that zinc white was used from the mid-19th century alongside lead white, initially in mixtures and later as a pure pigment. The study highlighted the limitations of identifying zinc white through non-invasive XRF analysis alone, recommending photoluminescence as a complementary identification method. Read the dissertation at University of Florence.
Key Artists and Paintings
J.M.W. Turner (1775-1851)
Turner was among the first major painters to experiment with zinc white. By the 1840s, he was using it alongside lead white, attracted by its cleaner, cooler tone. The transition is visible in his late watercolors and oils, where the white areas have a slightly different character from his earlier work. Turner's experimentation with zinc white was typical of his willingness to try new materials, though he reportedly found its longer drying time and lower covering power frustrating compared to lead white.
Claude Monet (1840-1926)
Monet used zinc white in his Impressionist paintings from the 1870s onward, particularly for the hazy, luminous effects in his series paintings. In Impression, Sunrise (1872, Musee Marmottan Monet), the pale gray-blue morning mist is built from zinc white mixed with small amounts of blue pigment. The semi-transparency of zinc white allowed Monet to create atmospheric effects that would have been impossible with the more opaque lead white.
Piet Mondrian (1872-1944)
Mondrian's transition from lead white to zinc white is documented in a 2023 study published in Heritage Science. Analysis of nine paintings dated between 1921 and 1935 showed that Mondrian used lead white in his earliest Neo-Plastic works, then switched to zinc white, often painting zinc white over lead white underlayers. In paintings from 1932 to 1935, he used a specific zinc white paint with aluminum phosphate inclusions, a formulation never before reported in the literature. This "marker paint" allows conservators to date Mondrian's works with unusual precision. Read the study at Springer Nature Link.
Karel Appel (1921-2006)
Appel and other CoBrA artists used zinc white extensively, as documented in the 2018 University of Amsterdam study of 179 paintings in Dutch modern art collections. The study found that many CoBrA artists preferred zinc white, which was the standard mixing white in European artist materials through the mid-20th century. This preference now poses a conservation crisis, as zinc soap formation in these paintings causes cracking, delamination, and surface blistering.
Barnett Newman (1905-1970)
Newman's color field paintings, including Vir Heroicus Sublimis (1950-1951, Museum of Modern Art), use zinc white in the ground layers and in the "zips" that divide the color fields. The semi-transparency of zinc white allowed Newman to build up thin, even layers that do not obscure the canvas texture, creating the flat, matte surfaces that characterize his work.
The Conservation Problem: Zinc Soaps
Zinc white's most significant drawback is its reactivity in oil paint. Zinc oxide is amphoteric, meaning it can react with both acids and bases. In oil paint, it reacts with the fatty acids in the drying oil binder to form zinc carboxylates, commonly called zinc soaps. These soaps can aggregate into crystalline inclusions that grow within the paint film, causing it to crack, delaminate, and develop surface protrusions. The process is slow, often taking decades to become visible, which is why zinc soap degradation in 20th-century paintings has become a major conservation issue only in recent years.
A 2025 study published in Heritage by researchers from Italy and the Netherlands examined the oxidative degradation of zinc white acrylic paint under artificial aging. The study found that zinc oxide plays a catalytic role in accelerating photodegradation of the organic binder, and that the degradation is unevenly distributed due to the heterogeneous mixture of zinc oxide and calcium carbonate extender in the paint film. The results provide fundamental insights into formulation-specific degradation processes and offer practical guidance for conservation strategies. Read the study at MDPI Heritage.
How to Spot Zinc White in a Painting
Zinc white is identifiable through XRF analysis by the presence of zinc. However, as the 2024 Florence dissertation noted, XRF alone can be unreliable for zinc white identification because zinc is a light element that produces weak XRF signals, and because zinc can be present as an extender or impurity rather than as the primary white pigment. Photoluminescence spectroscopy is a more reliable method: zinc oxide exhibits characteristic luminescence that can be detected non-invasively.
Visually, zinc white produces a cooler, cleaner white than lead white, but not as starkly brilliant as titanium white. It is the most transparent of the three major whites, which means it is often used in thin glazes or mixtures rather than as a standalone white. In 19th-century paintings, zinc white often appears in skies and atmospheric effects where its transparency was an advantage.
Zinc white was developed as a replacement for lead white and was itself largely superseded by titanium white in the mid-20th century. Many modern white paints combine titanium and zinc white to balance opacity with handling. The pigment is used in oil painting, acrylic painting, and gesso formulations. For more on how white pigments interact with other colors, read our entry on cadmium colors, or explore our post on how to read a painting.
See Zinc White in Person
Zinc white is visible in Impressionist and Post-Impressionist paintings at the Musee d'Orsay in Paris, particularly in Monet's series paintings where the semi-transparent white creates atmospheric effects. The Kunstmuseum Den Haag holds Mondrian's later works, where zinc white replaces lead white in the white planes of his Neo-Plastic compositions. The Stedelijk Museum in Amsterdam holds CoBrA works by Appel and Constant, where zinc white is now causing visible conservation problems.
For a comparison of all three major white pigments, look at a Rembrandt at the Rijksmuseum (lead white), a Monet at the Musee d'Orsay (zinc white), and a Pollock at MoMA (titanium white). The differences in tone, opacity, and aging are visible even without scientific equipment. For more on the pigments that shaped painting, read our entries on lead white and titanium white, or explore our guide to chiaroscuro and dramatic contrast.
