Over time , however , his use of lead paint has led to the darkening of several sections of these works .
These are among the greatest Martini 's works and the finest examples of 14th - century painting .
Over time , however , Martini 's use of lead paint has led to the darkening of several sections of these works .
These are among the greatest Martini 's works and the finest examples of 14th - century painting .