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Giovanni Benedetto Castiglione, An Offering to Pan​ (detail), c.1645–60. Photo: NGC

This painting I have seen countless times at the National Gallery of Canada in Ottawa on the second floor in the baroque room. It’s a very big painting and a fascinating one. The title of my post is about change, but what it refers to is the change that occurs in a painting over the years as paint ages and nature takes its toll. Like people paintings do age and decay with time and they need restoration and cleaning.

I presented this painting to school groups who come to the National gallery in Ottawa. Children and adults are fascinated by the subject and all the items shown. Doing interpretative work on paintings is to me always interesting, this is something I love doing.

This painting has changed, the colours are much darker with age. The darkening has changed the view we have of the painting.

Here is what Stephen Gritt, Director, Conservation &  Technical Research, at the National Gallery of Canada has to say about it.

When William Hogarth published his book The Analysis of Beauty in 1753, he touched upon a subject that could potentially strike fear into the heart of any art lover. “When colours change at all, it must be somewhat in the manner following, for as they are made some of metal, some of stone, and others of more perishable materials, time cannot operate on them otherwise than as daily experience we find it doth, which is, that one changes darker, another lighter, one quite to a different colour, whilst another, as ultramarine, will keep its natural brightness,” he stated. “Therefore how is it possible that such different materials, ever variously changing … should naturally coincide with the artist’s intention.” The English painter was stating, in effect, that art objects – here specifically paintings – begin changing right from day one, so what we ultimately see is not the work the artist originally intended.

These changes in a work may occur on their own, within the object’s raw materials – for example, drying oil in oil paints darkening over time. There are also changes that can be engendered by “misuse” of these materials, typically called “inherent vice”, for example when the use of too much oil produces even greater darkening. Although this term is usually thought to apply to works of art that may be experimental in nature and made in the last 50 years, artists have always pushed the limits of their craft and knowingly used materials that were going to change. One could argue that we have centuries of inherent vice with which to contend.

Typically the artworks we see today have changed in a way that stems from the interaction of these various phenomena and the environments in which they have been kept. What often has a more profound effect on the nature and appearance of these works is the way conservator-restorers have treated them, and what they may have done to correct or simply hide any changes. Today, one of the roles a conservator-restorer should play is to look at the forensics of the situation, while trying to unravel the causes and effects of the changes over time. If the conservator-restorer is able to achieve this, thoughtful treatment can mediate these effects and enable a presentation of the work that has it talking in something like its own voice once more.


Painted in the mid-17th century by the painter Giovanni Benedetto Castiglione, An Offering to Pan illustrates examples of such compound effects. The painting depicts an altar-like structure, heaped with offerings and trophies to a damaged sculpture of the ancient god Pan, shown in his characteristic form as half-man, half-goat. Pan was an embodiment of wild and eruptive nature, as well as fertility. His followers were mainly people in remote and rural areas, and in this portrayal one sees hunters, shepherds and herdsmen making offerings, in the hope that he will assist them.

Unlike depictions of the Classical world by Castiglione’s contemporaries, the eclectic and exotic nature of the clothing and objects is designed to invoke Pan’s non-Olympian strangeness, and potentially his origins in the East. Castiglione is attempting to bring that world to life by making it vibrant and exotic, full of unusual beauty, which allows him to show off his ability to represent the sumptuous and glittering bounty. Castiglione was also an excellent painter of animals, and the spaniel is simply one of the best depictions of a dog in the Gallery’s collection.


The upper part of the canvas shows some of the changes that have occurred over the years. In addition to the top section of the sky looking uneven and blotchy due to cleaning damage and discoloured old restoration, a horizontal line has become very prominent. It is a seam where two sections of fabric were originally stitched together to make the large canvas, and the seam has been pushed forward by past structural treatment of the painting.

The mottled cloud-forms should actually read as a more even, luminous pale blue, set against and contrasted with the gold colour. The blue pigment used here is called “smalt”, which typically decolourizes and ultimately is more susceptible to damage during cleaning operations. In this particular instance, the combination of the colour change in smalt, an increased visual effect of the dark red-brown underlayer and the significant cleaning damage twists the painting away from Castiglione’s originally realized intention.

On the left, the same effects can be seen in the darker clouds. The black lines rising up above the ducks are actually the artist’s initial drawing in paint, which has been revealed by the changes, and it appears that Castiglione originally intended to include a tree. On the right, the foliage of the trees has also changed over time. Green tints were typically based on copper, which causes the oil medium to turn brown. Pan was associated with springtime, and this change potentially takes the viewer to a different season. Overall, the effects of restoration processes and the basic aging of the materials will have caused the painting to be generally darker, and to have lost force in the mid-tones, creating an effect of heightened tonal contrast.

So what does all this mean? How does one interpret and understand works that are far from their intentional state? Much of Castiglione’s fine-tuning in finalizing this painting has simply disappeared, although some sections have survived relatively unscathed. As Hogarth noted, the blue ultramarine, used here in the mountains and drapery, has proved resilient, and now consequently stands out as strident.

This should give us pause for thought, but it should not be critically unnerving. With the right kind of information, one can meet the work halfway and, in turn, achieve something more meaningful. Helping us do this is one of the key roles of Museums, and has been since their inception. With enough information we can retrieve more of the work’s nature and its original grandeur and, in turn, engage with it and appreciate it in a more meaningful way.