Scientists also use these techniques to identify whether a piece of art is original or touched up based on knowledge of pigment history and X-ray spectroscopy.
New advancements are ebing made all the time. There are now non-organic resins available to replace the old natural yellowing ones. By studying what made the natural resins work, scientists discovered that the secret was to have a low-molecular weight and vicosity (flowabilty).
But a restorer must be careful because a loss of a work of art is not just bad for karma, but bad for the wallet.
Restorers have been sued for faulty and careless restorations.
One well-known team of restorers was cleaning frescoes in the Composanto in Pisa and allegedly applied the wrong cleaning solvent. They used ammonium carbonate which works well but has serious problems if it reacts with gypsm in the plaster. The reaction bleaches the pigments and creates calcium carbonate to powder on top which can not be removed.
In short, art is a science. No really, it is. and therefore, it is sweet.
Period.