Art historians and conservation specialists are always dismayed when the fine art restoration of a portrait by one of the Old Masters is completed, and the luminous colours and bright light of the original is revealed to universal confusion. Where is the warm gold and tobacco brown glaze we associate with the portraits of old? People are used to what they have been looking at for years, and when the oxidised old varnishes are removed, revealing the colours and light of original works, they seem very bright to our eyes.
But the dismay never lasts, as we are allowed to study the painting as it left the studio, and we can see new elements and new contrasts, brush strokes and tiny details obscured by years of old varnishes getting darker, and the environmental degradation of the paints and substrates.
Portraits tend to be painted on very fine substrates, so the textures of the canvas do not interfere with the painted image. Wooden board is popular, and very finely woven linen canvas. These substrates last longer than more textured cotton canvas, but any organic materials will respond to the environment over time.
Artists protect the surface of a painting with varnish. Even best quality oils and acrylic paints, egg tempera, watercolour, pastels, gouache, will absorb humidity, collect dust and dirt, and react to air and water over time, oxidizing and darkening. Varnishes are designed to protect the surface from light, humidity, and the effects of the environment, such as dust. But since varnishes of old tended to be made of natural materials, they also oxidised and were affected by the environment over time.
The majority of old varnishes darkened to a warm honey gold to tobacco brown colour over time, becoming more translucent, then opaque. Modern restoration of portraits involves first cleaning the surface to remove dirt and dust, and then evaluating the chemical composition of the varnish, so it can be safely removed without impacting the paint underneath.
Once the varnish is removed, the painted surface is examined closely, and any damage repaired. Many times, a substrate is backed by another to give the painting additional stability and longevity. Modern conservation-grade varnishes are designed to be completely reversible, so if in the future it is discovered that they are beginning to degrade and change colour, or otherwise interact with the environment, they can be easily removed from the surface and replaced. However, the modern varnishes are manufactured with ingredients that are environmentally stable, and should not interact with light and moisture the way the older varnishes did.
Are you considering having a portrait evaluated for conservation and restoration? We would be pleased to be considered. Please contact us for an appointment.