Portrait during removal of the varnish
On ageing, varnish may oxdizie and become very yellow. This discolouration will change the tonal balance within the painting, making it appear significantly different from how the artist intended. To change this, the degraded varnish might need to be removed and replaced with a new varnish layer that has better ageing properties.
Painting with a strongly yellowed varnish and discoloured retouches
Same area during removal of varnish
Finished varnish and overpaint removal
Gel for the removal of varnish
A varnish removal is usually carried out with solvents adjusted to safely solubilize the old varnish without affecting the paint layer. This can be done in various way, with free or gelled solvents or even with microemulsions.
This step should only ever be carried out by a qualified conservator!
Detail of discoloured retouches
Same detail after the removal of overpaint
Old restorations or retouchings may also be present on the surface when removing the varnish layer. These in many cases discolour and hide the artist’s original brushwork and even extend far beyond the damage itself, as in the example on the left.
In many cases the old restorations can be removed with the same solvents as used for the varnish removal.