The restoration of the Prado's miniatures collection and the study of their state of preservation have revealed the stability of these works when they are kept in stable environments and have not been treated with inappropriate materials, given that the damages found were generally due to old manipulation or restoration that altered the state of the materials.
Restoration criteria for works of this type should aim to preserve the original technique and methods, involving the minimum degree of intervention necessary with the aim of recuperating and preserving the original material. For this reason older treatments such as sanding down to remove stains, whitening the ivory or filling in paint losses were considered inappropriate as procedures of this type on objects of such delicacy conceals the works themselves, making it difficult to see the image and preventing the recovery of the original painting.
During the restoration of the collection a specific study was undertaken on each work's state of preservation. While the techniques were comparable, each miniature was a separate case with specific issues that required a precise and particular approach to restoration with the aim of avoiding both invasive treatments and those that could result in new conservation problems in the long term.
Elena Arias Riera. Restorer. Museo Nacional del Prado