History, Preservation, and Restoration of Oil Paintings on Copper
While wood panels and canvas dominate the history of oil painting, metal, particularly copper, has served as a distinctive and durable support since the late Renaissance. Emerging in 16th-century Italy and rapidly adopted across Flanders, Spain, and beyond, copper offered artists an exceptionally smooth, luminous surface well-suited to fine detail and brilliant color. Despite its relatively limited use compared to traditional supports, painting on copper developed into a refined practice among elite workshops and court painters, leaving behind a rich legacy of small-scale, jewel-like works. This article traces the global history of oil painting on metal supports, with a focus on copper, examining the technical methods used by artists, the advantages and challenges posed by the material, and both historical and modern approaches to preservation and restoration.
History of Oil on Metal Supports
Painting with oil on metal sheets (especially copper) emerged in the Renaissance and flourished in 16th–17th-century Europe. Its roots lie in even earlier metalwork traditions (glazing techniques like medieval cloisonné) but oil-on-metal came into its own during the 15th century. Vasari’s Lives notes that Sebastiano del Piombo (1485–1547) painted on copper, and Correggio (d.1534) executed a Penitent Magdalene on copper.
Antonio da Correggio, Penitent Magdalene . Image from Wikimedia Commons.
By the 1560s even Medici court painters (Vasari, Bronzino, Allori) used copper panels. Northern artists picked up the practice in Italy and brought it home, Van Mander reports Spranger and Rottenhammer painting on copper in Rome. By the late 1500s and early 1600s, painters like Jan Brueghel the Elder, Joachim Wtewael and David Teniers the Younger made hundreds of oil on copper miniatures. In short, oil-on-copper was widespread across Italy, Flanders, the Netherlands, Germany, Spain (and even New Spain) in the 16th–17th centuries. Its popularity waned after 1650; by the 18th century copper supports were seldom used.
Over history, a few artists outside this core tradition also painted on metal. 18th- and 19th-century painters like Chardin, Copley Fielding or Carle Vernet occasionally used copper. More recently (20th–21st century) a small “resurgence” of interest has appeared, with contemporary painters such as Kate Lehman and Karina Keri-Matuszak intentionally using copper supports as a nod to old masters.
Preparing Copper Supports
Artists made their own copper panels by hammering or rolling sheet copper. Early copper plates were often uneven – hammered plates show faint dents and rolling marks under raking light. Before painting, the metal surface was carefully prepared. Historic sources instruct rubbing the panel with fine abrasive (pumice, emery or sandpaper) and even raw garlic juice. Garlic was believed to clean the copper and “create a more even surface” for paint. Numerous 17th/18th‑c recipes say to “dress & pumice” the plate. After abrasive cleaning, painters often applied an ultrathin oil ground (essentially a primer) of white lead (and sometimes chalk or umber) in oil. For example, Pacheco (1649) instructs that “plates are prepared with lead white, and umber in oil”. Analytical studies of period copper paintings confirm a very thin (10–20 µm) ground of lead white/carbon black (and occasional vermilion or red lead). These scant grounds leveled the surface and gave initial “tooth” for adhesion. Importantly, the ground was applied sparingly – treatises even advise using fingertips to spread it evenly, since a heavy gesso defeats copper’s advantage. In modern practice some artists omit oil ground altogether: if the metal is very clean (e.g. degreased with alcohol), one can paint directly on bare copper. However, many still use a single thin oil-priming coat (lead white, alkyd ground, or even diluted shellac) to ensure grip.
Painting Techniques
Oil painting on copper tends toward highly finished, small-scale works. Because copper is so smooth and reflective, artists could build extremely fine detail and luminous color. In practice, painters often began with a detailed underdrawing or underpainting to “grab” the metal (since early layers slip on bare copper and then applied thin glaze layers to achieve depth. The non-porous metal means paint is not absorbed; rather the copper “inner glow” back-lights transparent layers. Conservators note that a copper support “can increase color saturation” and impart a warm reddish tone to glazes. In Hendrick van Balen’s Adoration of the Magi (c. 1625, 16.5×13 cm) – an oil on copper panel – the jewel-like reds, greens and golds still shine brightly after centuries. Modern artist Melinda Whitmore remarks that transparent pigments like rose madder, chrome yellow or ivory black look extra vivid against copper’s shine.
Rembrandt, Self-Portrait, 1630, oil on copper. The smooth copper surface let Rembrandt achieve exceptionally subtle modeling and luminous flesh tones.)
Because copper holds little texture, painters often built up very thin layers. They applied multiple translucent glaze passes, allowing earlier tones and the copper base to show through. Some artists even used chemical oxidation (patina) artistically: acids or salts were applied to create blue-green verdigris or blackened metal as part of the image. Historically, after each layer dried, a very thin oil varnish or siccative resin might be added to stabilize the paint and speed drying. Modern artists typically varnish finished copper paintings to protect them from oxygen and moisture. Overall, the technique emphasizes careful layering, fine brushwork and patience.
Advantages and Challenges
Copper (and other metals like tin or zinc) offered painters unique benefits. The advantages include: extreme rigidity (no warping or sagging) and immunity to insects, rot or mold – copper “will not rot, mildew or be eaten by insects” as wood might. Its thinness and light weight (compared to equal area of wood) made panels easy to frame and transport. Copper’s inherent color (warm orange-red) could subtly warm the painting, similar to a pink ground. Critically, because it absorbs none of the oil, all the applied pigment retains its full brilliance. As a conservation report notes, paintings on copper “often retain their brightness and condition better than those on canvas”. The smoothness of copper means brushstrokes can be imperceptible – details are razor-sharp. For instance, miniature portraits and still lifes on copper are renowned for their intricate precision and glazing effects.
However, these properties also introduce challenges. The very smooth, hard metal gives initial paint little to grab onto. Artists experienced that “paint slips and slides around” on a bare copper plate, so they typically had to roughen the first paint layers. Many built texture in the underpainting (often in the light areas) precisely “so subsequent layers can grab onto [it] more effectively”. Even with a ground, adhesion can be delicate because copper’s impermeable surface tends to resist oil uptake.
Once painted, copper panels present other risks. The paint layer is usually very thin (on the order of 10–20 μm)j, so it is easily abraded or scratched. Small knocks or rough handling can remove paint. Also, although copper itself is dimensionally stable (RH changes cause “negligible” expansion), it can corrode chemically. Prolonged exposure to moisture or salts (even from polluted air or acidic mat boards) can oxidize the copper. This corrosion can form greenish copper-carboxylate complexes (verdigris) at the interface, weakening paint adhesion. If the bond loosens, the paint film may blister or flake off. In extreme cases, reactive conservation mistakes (like aqueous cleaning) have even etched the metal.
Proper care is therefore crucial: it’s best to keep copper paintings dry and stable in temperature/humidity. Frames often include a rigid backing board to prevent any bending of the thin metal. Specialists advise using only pH-neutral glazing and mats, as acidic materials can catalyze metal corrosion. Interestingly, putting copper under glass must be done carefully – trapped moisture between glass and paint can create a micro-climate that actually accelerates verdigris.
Notable Artists and Works
Many famed masters painted on copper. For example, Flemish artist Ambrosius Bosschaert II and Dutch miniaturists like Ambrosius Goudt used copper for flower and wildlife scenes. El Greco executed small devotional figures on copper, and Guido Reni, Guercino and Saraceni all used copper panels for mythological and religious subjects. Among the Dutch, Joachim Wtewael was a prolific copper painter, and Jan van Kessel used the medium for intricately rendered insects and plants. The Courtauld recently studied a 1600s St. Jerome on copper (after Palma Giovane), noting that “paintings on copper often retain their brightness and condition”. In Britain, John Singer Sargent and other portraitists preferred canvas, but British watercolourists occasionally sketched in oils on copper.
Hendrick van Balen the Elder, Adoration of the Magi, c.1625, oil on copper (16.5×13 cm).
Hendrick van Balen the Elder’s Adoration of the Magi shows the intense color and fine detail possible on copper. Copper panels were ideal for such cabinet-size works. Brueghel’s son-in-law David Teniers even painted the grand Archduke Leopold Wilhelm in his Gallery (c. 1650) on a large copper sheet.
Copper painting is uncommon today, but a few modern artists experiment with it for its unique “gem-like” effect. For example, abstract painters Karina Keri-Matuszak and Kate Lehman work on copper or copper-clad substrates to create highly saturated, reflective effects. Also, commercial suppliers now produce pre-made copper panels (often aluminum-backed or lacquered) for artists who wish to try this historic support.
Preservation and Restoration
Conservators generally find copper supports to be fundamentally stable under proper conditions. Unlike wood or canvas, copper does not warp or shrink with humidity, and it normally supports centuries of paint without delamination. However, treatment of copper paintings requires caution. Cleanings must avoid water: conservators use solvent gels and organic solvents (no water) to dissolve surface grime. During varnish removal or cleaning, each solvent swab is changed frequently to prevent contaminating the metal. Any time moisture contacts the copper it may cause oxidation, so even storage humidity above ~65% must be avoided.
If cracks or flaking appear, conservators consolidate them with carefully chosen adhesives. Because the metal is impermeable, they often apply adhesives by micro-injection under each flake Loose fragments can be re-affixed and losses filled with inert putty and inpainted. As always, treatments are tailored individually – two paintings of the same period may use different binders or corrosion states, so each is tested first. After treatment, many copper paintings are kept behind glass with silica gel or in airtight enclosures to slow any further corrosion.
In preventive terms, copper paintings should be framed rigidly (with backing boards) and kept in a dry, stable environment. Avoiding touch and abrasion is key, since the paint is delicate. When displayed, minimal direct light is also wise (bright sunlight can heat the metal). With such care, historic copper-based works can remain vibrant for centuries. Indeed, collectors often treasure oil-on-copper pieces precisely because, if intact, they look nearly as fresh as the day they were painted.
