Cleaning and restoring paintings

Cleaning can revive the look of a painting dramatically. Sometimes simply surface cleaning and revarnishing a picture can be transforming.

Most oil paintings are coated in a layer of natural resin varnish, which wets out the colours and made the picture look lustrous. It also serves to protect the surface from atmospheric pollution and grime, and eventually becomes a sacrificial coating which needs to be replenished from time to time. Modern conservation varnishes are designed to be removed easily from oil paint, but even this task requires the skills of an experienced restorer, all the more so if a historic varnish is very old, hard, or thick.

Nearly all old paintings are peppered with small damages. More serious tears and lacunae, being more likely to occur towards the middle, can affect areas of face and other details requiring painstaking reconstruction.


The removal of dirt and varnish is carried out with solvents and other mild chemicals. Because dirt gathers very slowly on the surface of a picture, it can be very surprising how much difference even surface cleaning can make. Traditional resin varnishes usually become more golden – and slightly opaque – with age, which can upset the colour values and contrasts within the composition. Cleaning can be a very cost-effective way of quickly improving a painting’s impact. Of course, any old damages would be revealed, but these can be carefully restored with the minimum of fuss.


At Cooke and Sons, all restoration is done within the varnish layer, using pure powdered pigments. The retouchings are built up as the varnish is, and the paint medium used in the restoration is therefore the same varnish as that one coating the finished picture. This makes the added material easily removed in the future, a basic principle of modern conservation.

Our restoration ethos is always to disguise if possible rather than cover over, using the minimum touches of paint, and the fewest number of pigments in the mix. Years’ of experience has led to a working method that addresses the most visually disturbing marks first.

Conservation: Structural Treatments

By far the most frequent structural treatments done at Cooke and Sons are to minor bumps and dents in the canvas support, and small areas of cracking that have built up over time. A little like restoration, attending to these small discontinuities in the surface can transform a painting. More general cracquelure can be treated, sometimes without further reinforcement of the canvas support, but more usually by lining the painting onto a new linen canvas to provide added support into the future.

Cooke and Sons are specialists at traditional glue-paste lining, which as a general treatment for more deep-seated distortions has a number of important advantages. As it is a process as well as a structure, we are able to utilize it to treat raised cracking and other surface defects. The finished lining has sufficient stiffness to hold and support these defects over time. Being a tried-and-tested method, using simple organic materials whose  characteristics are known, its future performance and removability is predictable.

We are also equipped for the treament of paintings on wood panel: split repair, servicing of existing cradles, or the addition of useful wood slips to aid full-width framing.

Our working methods
Cooke & Sons

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