Painting Restoration – a snapshot of what’s involved

What is the most common type of painting that needs restoration?

The traditional oil painting is the most common type to come to my studio for painting restoration. This is more a statement about the popularity of the medium than it is about its instability. In fact oil paint on linen canvas is still one of the most popular and stable combinations of painting materials available. There are still so many examples in existence of beautiful oil on canvas paintings dating to the 17th century. Many have survived with much of the original paint layer in tact. This is a true testament to the superiority of the medium. Whether modern painting materials such as acrylic paints will last just as long, we can’t say as we don’t have the historical proof. Acrylics have only been around since the 1950s.

painting restoration

Oil painting materials:  red pigment in the centre, linseed oil on the right, and a glass muller on the left to thoroghly mix the 2 ingredients

Why are oil paintings so long-lasting?

The secret to this question lies in the oil paint recipe. Traditional oil paint is made up of 2 main ingredients. Yes, just 2! There’s the all important colourant in the paint, referred to as the ‘pigment’. It’s usually a lump of coloured mineral or rock that has been ground down to a very fine dry powder. Then you also have the ‘binder’, which is linseed oil. It looks a lot like cooking oil when wet, but linseed oil is a drying oil. This means it gradually undergoes a 3 step chemical process as it dries, to become a strong, unified and impermeable layer. It’s the drying oil in the paint that makes oil paintings as tough as they are.

What are the main types of damage to an old oil painting?

Painting cracking

Cracking caused by a blow to the painting

The obvious causes of damage to a painting are of course physical impacts such as a blow to the surface. This can result in paint loss or a scratch around the impact site. But it can also lead to a series of cracks in that location. Even a fairly soft blow to a painting on canvas can lead to a tear in the canvas, if it’s quite old and the canvas has become brittle with age.

However even if your painting hangs on the wall well out of reach of clumsy hands, your painting will undergo chemical changes over time. The first signs of ageing in an oil painting is the slight gradual darkening of the paint. This happens over several years and decades after the painting was made. It’s caused by the darkening of the linseed oil component, though generally you won’t even notice it. If your painting has been varnished, then much more disturbing is the darkening that occurs in a varnish layer as it ages. A dark varnish can really change the look of the colours in a painting and the clarity of the artist’s work. To learn more about a varnish removal treatment, go to my article on ‘Cleaning a Painting’ here.

What other types of damage do you commonly see?

The paint also gradually loses its flexibility and becomes more brittle. At this point it can start to crack. Where an artist has used cheaper quality paints for their artwork, this can often lead to a greater level of cracking in the paint layer and sometimes to mould attack. The cause of the increased cracking and mould growth is the chalk filler that has been added to the paint. It replaces some of the pigment, making it cheaper to produce.

Paint flaking and lifting is another common condition seen by painting restorers. It’s caused by the movement in the painting. Linen and cotton canvases tend to move with changes in humidity in the air. This causes the canvas to expand and contract. The movement in the canvas also forces movement in the paint. With older, less flexible paint-films this can result in cracks and potentially in paint flaking, as the expansion and shrinkage forces on the paint become too great.

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Detail of oil painting on board with severe paint cracking and flaking

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Detail after painting restoration. Painted by Robert Finlayson

Probably the most common situation with a painting though is dirt build-up on the surface of the paint. If your painting has lived with you for around 20 years and it hasn’t been sponged down by a resident ‘DIY restorer’ (something I don’t recommend), then it will likely have a layer of dirt over it. Sometimes a dirt layer can look almost as disturbing as a darkened varnish. Both dirt and dark varnish can completely change the colours in your painting. See my article on ‘Cleaning a Painting’ if you’d like to know more about these 2 conditions.

art restoration Katoomba

Detail of oil painting by Jan Schmidt undergoing varnish removal – the right half is cleaned, the left half is still untreated

What can you do to repair a damaged painting?

There’s a lot a qualified painting restorer can do to help an old or damaged painting. Perhaps surprisingly to some people, none of it involves using a magic wand. Though many people seem to view painting restoration as something quite magical. First I’ll usually try to work out the cause of the damage. That’s because it might effect the way I choose to restore the artwork and the materials I select. Then I’ll focus on repairing the damaged painting.

When a paint layer is cracked or has suffered paint loss, this usually involves introducing a special adhesive to secure the damaged paint. It ensures that the paint doesn’t start to lift or suffer further loss. Once the paint is secure, any paint losses can be filled and retouched. This can completely mask the damages so you wouldn’t even know they were there. If your painting has developed a tear to the canvas then the broken and ruffled canvas threads can be re-woven and sealed back together. By re-weaving a tear in this way, you can quite successfully hide it from view. A painting can be carefully cleaned to remove a disturbing dirt layer. And a varnish removal treatment can be undertaken to remove a darkened varnish. Refer to my article about ‘Cleaning a Painting’ to find out more about either of these treatments.

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Painting detail with a large tear in the canvas

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Detail after painting restoration

What about a really old painting?

For paintings older than about 100 years, it is common to encounter the work of a previous restorer. Sometimes a large part of the treatment can involve removing the now darkened retouches and varnish coatings applied by the restorer. Painting restoration ethics, techniques and materials have changed and developed so much in the last 60 to 70 years. For several centuries restoration was a trade practiced by artists. They would often bring their own artistic flair into the work as they over-painted large areas of a damaged painting.

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Australian Impressionist painting with large areas of overpaint within the sky and the dirt road. The overpaint has changed the colour palette of the painting and the sense of the time of day

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Painting following varnish removal and overpaint removal, restoring the artist’s original colour palette. Painted by Albert Henry Fullwood

Now it’s a scientific and highly analytical profession that respects the artist’s work and their intention, above all else. Today it’s considered inappropriate to cover any of the artist’s original paint. Restorers would previously often use the same materials employed by the artist. Materials are now chosen for their stability, their tendency not to darken or yellow and their ability to be separated from the original. The aim is not just to increase the lifespan of the painting. It’s also to improve the long-term appearance of the restoration work and allow the restorations to be removed in future if needed.

Written by Kristel Smits

Kristel Smits

Kristel Smits is a painting conservator who runs her own practice, K.S. Art Restoration. Located in the Blue Mountains, west of Sydney, she restores paintings for private clients and Regional Galleries. She has 25 years experience in art restoration. To find out more, visit her ‘About’ webpage here.