Gesso application.
The gesso used is Bologna gesso (or gesso for gilders) and rabbit-skin glue.
It’s the traditional ancient preparation for gilding.
It’s a long process, in which several coats of gesso are applied until the desired thickness is obtained.
Drying times must be respected between each coat to achieve a good result.
This is an important step, that requires careful attention to ensure a perfect base for the gold leaf to be applied.
Any imperfection will be visible in the following steps.