Conserving the frame: step by step


Five days into our campaign to raise the £15,000 we need to conserve the frame of The Snake in the Grass, Head of Conservation Jane Wilkinson explains the painstaking process that we’ll undertake to return the frame to its former splendour.

At Sir John Soane’s Museum we have a very particular approach to how we conserve objects. While we need to keep the works of art in the best possible condition, we always try to preserve any details and finishes that have survived from when Soane displayed them. This means that the process of conserving the frame of The Snake in the Grass is especially complex, with careful testing and examination needed before we can treat it.

What we know about the frame

The frame dates from the late 18th or early 19th century. Frame-making was an important industry at this time, with whole workshops of skilled craftsmen using complex techniques to create highly decorated frames.

The main structure is made of wood, with applied decorations that are not carved but made from a material called composition – usually shortened to ‘compo’. This is a dough-like substance made from mixing whiting and animal glue with linseed oil, rosin and Venice turpentine. When this mixture is heated, it softens and can be pressed into carved wooden moulds to produce elaborate decorations that are then fixed to the frame.

Over this structure several layers of gesso, a creamy mixture of whiting mixed with water and animal glue, are applied. This creates a smooth surface for the gold leaf to be laid on. Before the gold is applied the surface is usually coloured. The brand-new frame would have looked extremely impressive, but over the last 200 years the surface has become dirty, the gilding flaky and unstable, and there is damage to some of the gesso.

Testing and cleaning

The first stage of conservation is to clean all the surfaces. We have had very good results cleaning gilded frames in the collection in the past, but every frame is different. Before we can start, we have to carry out tests with a range of solutions to find one that will clean the delicate surface without damaging it. With the right solution, we hope that once the dirt is removed the appearance of some of this frame’s original gold will be good enough to keep.

Consolidating, gilding and toning

We may need to consolidate some of the old gold where it is unstable, and we will definitely need to repair some of the gesso. Once all these repairs are completed, new gold will be applied to the repairs and to any areas where the gilding is lost. New gilding can look positively ‘blingy’, so the next process is to tone down this gold to match the old. We do this by distressing the new gilding and toning it with watercolours mixed with animal glue, using traditional methods.

Finally, we will apply a thin coat of gelatine over the whole surface of the frame to protect the gold from dirt and pollutants.


After three months of work, the conserved frame will be reunited with the painting. We hope the impact on visitors will be as powerful as it was on Sir John Soane when he first saw the painting at Christie’s Auction House in May 1821. You can join us to see the unveiling of the new frame as one of our exclusive rewards – find out more and donate here.

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