With testing out of the way it is now time to commence the varnish removal. It comes as a surprise to some people to learn that the cleaning can be a relatively quick part of the restoration process. With the Crossing of the Red Sea we have anticipated that the cleaning time required will take up only one month of the twelve we have set aside for the treatment, though that will be subject to revision if we encounter any unexpected problems.
Like the testing, the varnish removal itself will take place in stages:
First stage of varnish removal
If the solubility tests suggest the cleaning will not present any particular problem, the first part will involve a first broad cleaning across the painting. The aim of this step is to remove the bulk of the discoloured varnish and restorer's retouchings, leaving fine residues and hard-to-remove retouchings for a later secondary cleaning. Doing it this way gives you an opportunity to assess the cleaning in a gradual and considered way and allows for adjustments to be made you go along. For example the conservator can vary the proportions of the solvents used as it the varnish thins down.
Second pass of varnish and overpaint removal
The second pass allows the painting to be cleaned to a more refined level of consistency across the surface and allows for any problematic areas to be cleaned on their own terms. Quite often older restorer's retouchings were painted in oil, making them more difficult to remove. Removing them during a second stage of cleaning enables them to be treated locally.
Mechanical removal
Sometimes old retouching paint and varnish is resistant to solvent cleaning. When this occurs, they may need to be cleaned mechanically. This is often done manually with the aid of a scalpel, delicately scraping or chipping the non-original components away from the original. This is almost always done under magnification, either with a magnifying loup or else under a stereomicroscope. It can be very time-consuming.
Final Balance
The later stages of cleaning are about ensuring that the painting has been cleaned to a consistent level of finish. Throughout the process the conservator ought to have developed a clear idea of what he or she wants to achieve with the cleaning and what is the best that can be reached given the variables involved: the condition of the original paint layers; how vulnerable they may be to the cleaning solution, the feasibility of removing the varnish and overpaints, the aesthetic implications of removing the non-original components, and so on.
Ideally the final balancing stage of cleaning provides the opportunity for final subtle adjustments to be made to reach the appearance required.
First stage of varnish removal
If the solubility tests suggest the cleaning will not present any particular problem, the first part will involve a first broad cleaning across the painting. The aim of this step is to remove the bulk of the discoloured varnish and restorer's retouchings, leaving fine residues and hard-to-remove retouchings for a later secondary cleaning. Doing it this way gives you an opportunity to assess the cleaning in a gradual and considered way and allows for adjustments to be made you go along. For example the conservator can vary the proportions of the solvents used as it the varnish thins down.
Second pass of varnish and overpaint removal
The second pass allows the painting to be cleaned to a more refined level of consistency across the surface and allows for any problematic areas to be cleaned on their own terms. Quite often older restorer's retouchings were painted in oil, making them more difficult to remove. Removing them during a second stage of cleaning enables them to be treated locally.
Mechanical removal
Sometimes old retouching paint and varnish is resistant to solvent cleaning. When this occurs, they may need to be cleaned mechanically. This is often done manually with the aid of a scalpel, delicately scraping or chipping the non-original components away from the original. This is almost always done under magnification, either with a magnifying loup or else under a stereomicroscope. It can be very time-consuming.
Final Balance
The later stages of cleaning are about ensuring that the painting has been cleaned to a consistent level of finish. Throughout the process the conservator ought to have developed a clear idea of what he or she wants to achieve with the cleaning and what is the best that can be reached given the variables involved: the condition of the original paint layers; how vulnerable they may be to the cleaning solution, the feasibility of removing the varnish and overpaints, the aesthetic implications of removing the non-original components, and so on.
Ideally the final balancing stage of cleaning provides the opportunity for final subtle adjustments to be made to reach the appearance required.
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