Cleaning seems a simple process and i have seen people in charge of historically important collections doing disastrous actions leading to irreversible damage of important art or history objects.
It might apparently be a simple cleaning job, but it is the most important step that needs to be understood in all possible analytical and scientific ways before actually doing it. This is so, because, it is an act of removing an unwanted surface accretion which might take with it an important part of the original object. In other words, it is an irreversible process where we might not be able to put the original particles back to where they belonged, if we accidentally remove them along with the unwanted accretions.
The video attached is using one of the many treatment methodologies possible. We have to judge which one suits the best after a careful analysis.