WHAT IS METAL LEAF?

And how does it differ from gold leaf and Roman bronze as a gilding material?

Metal leaf is an alloy of copper and tin that is made in thicker, larger sheets than that of gold leaf. Its thickness and brassier color distinguish it from gold leaf, yet this subtle difference is not always apparent to the untrained eye. Used primarily as a less expensive alternative to gold leaf, metal leaf always tarnishes or darkens over time, whereas gold leaf does not. Additionally, because of its thickness, metal leaf is less malleable than gold leaf and, therefore, cannot be as easily applied to more detailed, intricately carved frames. Its copper and tin composition makes it unsuitable for water gilding and burnishing, a technique that produces the highly polished surface typical of frames gilded with gold leaf.

Over the centuries, frame makers have used Roman bronze also known as Roman gilding or burnished bronze in the gilding process in an effort to minimize costs. Made with a powder comprising very finely ground particles of copper and tin and suspended in a binder containing either a water-based gelatin or rabbit-skin glue, Roman bronze is painted on the frame rather than applied in sheets like metal and gold leaf. Roman bronze and metal leaf look similar in color to the naked eye, but metal leaf appears as a sheet-like application, whereas Roman bronze appears as tiny particles on the frame’s surface. As a result, each reflects the light differently. Unlike metal leaf, Roman bronze, which is applied like gold leaf over a traditional clay bole, can be lightly burnished to simulate more closely the soft, lustrous surfaces produced by gold leaf. For this reason, it was used by frame makers and frame designers such as Stanford White to create subtle contrasts in gilded finishes.

When Lowy restores important frames that have been originally finished with metal leaf or Roman bronze, the intended patinas are preserved. But if a frame has been covered in bronze paint, sometimes called 'radiator paint', during a poor restoration, Lowy will clean the frame and try to save as much as possible of the original finish underneath. Both the modern and reproduction antique frames created in the Lowy workshops incorporate only the higher quality 22 or 23 karat gold leaf in their finishes.

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