Conservation: Cleaning @ National Museums of Liverpool

We would usually know if a painting needs to be cleaned as a result of initial examination where we would be aware that there is any some surface deposit or surface dirt or discoloured varnish or we had some existing knowledge of the condition of the picture. Colleagues of ours photograph the paintings and then we can tell with things like ultraviolet photography what's going on with the surface and we can identify from a lot of these methods what's going on and whether there's a need to think about cleaning the picture. They usually need cleaning because over the years even atmospheric pollution and dirt can settle on the surface and that can make a very very big difference to how the picture appears. The surface can appear dull and grey and particularly if the painting isn't behind glass the surface deposits from city and traffic pollution can be quite significant over a number of years and if it's not been looked at for a very long time even things like excess coal smoke pollution from the 1940s and 50s can still have an effect on the surface now if it hasn't been cleaned since then. The cleaning process usually starts with a very basic look at the surface and we might try and get off some of those atmospheric dirt or surface pollutants just dust grime it can even be nicotine smoke if the paintings been somewhere not so much in a gallery but in a private house where there's been somebody smoking you can get quite heavy deposits from that. We would normally check the surface and do some cleaning tests to make sure what we're dealing with and find out what's the most appropriate method. When you're cleaning a painting you need to consider what the surface of the picture is what the medium of the picture is and often what's been done to it before. You'll always be carrying out safety margin tests to work out what coatings are that you're trying to remove and being very careful to make sure that you're using the right cleaning agent or solvent that will match what you're trying to remove so there's no risk to the original paint. Today we were looking at a painting by a French artist called Sonterre and this was the review to removing an awful lot of surface dirt from the picture which we do with small cotton wool swabs and this has made a huge improvement to the surface because we've actually found that the varnish underneath is still in very good condition it was just completely masked by the dirt on the surface.