Whitening caused by fixatives and saline deposits

Whitish patinas
This refers to the whitening of the paint film caused not only by saline deposits but also by coats of consolidating or protective agents which have now deteriorated. This whitening effect, more or less pronounced and anyway confined to circumscribed areas, can be seen on all the frescoed surfaces.
Investigations seem to show that this effect is mainly caused by saline deposits, and that it occurs most obviously in areas previously affected by rainwater infiltration.
In some cases, the whitening tends to follow a pattern of parallel bands reflecting the structure of the underlying masonry with its brick courses.