The conservators continue the process of inpainting. They apply color to areas of loss to create a faux finish that fools the eye and integrates the damaged areas into the overall design. This way, when you look at the painting, what you have is the aesthetic pleasure of seeing the design as a whole without your eyes being drawn to areas of loss or damage.
Inpainting requires staying within the confines of the actual loss. It is inappropriate to paint over or cover any of the original painting.
The materials used in inpainting are a synthetic resin mixed with dry pigments. The reason these are used is that they can be easily distinguished from the original materials that the artist used. They are also easily removed without damage to the original paint layer.