Q How does science protect great works of art?
— Ruby Taggart, Merrimac, Wis.
A Maria Saffioti Dale, curator of painting, sculpture and decorative arts at the Chazen Museum of Art, Madison, Wis.:
Art conservators can use different wavelengths of the electromagnetic spectrum, like X-rays and infrared technology, to learn more about how a painting was made, the structure of the painting, the paint layers and what happened to a painting over time.
For example, the Chazen Museum of Art has a 17th-century painting by an Italian artist named Elisabetta Sirani. The work was painted in 1661, a portrait of a woman holding a basket of apples and roses in the likeness of Saint Dorothy.
When conservators did some cleaning tests on the painting, they uncovered irregularities on the surface of the work. Some technical analysis was then performed using X-ray technology.
In an X-ray of this painting, you can see the structure of the canvas, the nails holding it to the frame and the actual physical composition of the art. What the X-ray shows and confirms is that part of the canvas, the lower left corner containing the basket of apples and roses, was moved from a different location in essentially a cut-and-paste scenario.
It’s possible the original canvas was larger and longer and the artwork was damaged in some way over the centuries. Someone wanted to preserve the image of the basket — the roses and apples being the main symbols of the saint — so they cut and moved it further up in the painting.
The X-ray reveals the fiber pattern of the canvas and shows that corner as slightly deformed and out of place. Infrared technology also shows that some painted leaves were added to cover up the seam of the cut-and-paste job.
X-rays can also shed light on the technique and materials used by the painter. In Sirani’s painting, the flesh areas particularly around the face and neck look bright white under X-ray, meaning the rays of light cannot penetrate the paint. This indicates to art historians and art conservators that lead white was used, a typical pigment in this period.
Learning as much as possible about works of art, whether it be an oil painting or sculpture or textile, can help conservators determine the best ways to protect and preserve these historical objects.