Reversibility in restorative treatments in general is a condition and criterion of great consideration. It is part of the same restorative function to be able to go back on improvable treatments for the conservation of the restored artistic object or document.
Reversibility criterion concept
It is one of the principles inspired by Cesare Brandi for the conservation and restoration of antiquities embodied in the Rome Restoration Charter (1972). Along with other criteria, such as the minimum intervention and making preventive and more conservative treatments prevail. These are, in my opinion, the support of the entire development of this Charter, and the following ones, in the face of the most interventionist criteria. In summary, this principle of reversibility expresses the importance that any intervention and / or treatment be as safe as possible. And including the replacement, change and withdrawal of the treatment in question. All this without or with the least damage to the original object, always bearing in mind that any intervention has a minimum degree of invasion in the original work.
And to explain this concept and its practical consequences with an example, I have brought the following experience and its follow-up. It is an oil on canvas from the second half of the seventeenth century belonging to the parish of San Pablo in Zaragoza. It is a Saint Joseph with the child Jesus, a work that has already been intervened without documentation, but not too long ago.
This is so because in that undetermined intervention, a traditional lining with flour porridge was carried out. This procedure is traditional, and if done properly, it guarantees a controlled reversibility, without causing damage to the original work. Therefore, this work was carried out by a professional from the restaurant industry who is familiar with the problem in question. Possibly it was made in the last third of the last century, it seems to comply with the traditional procedure and materials to use. And the reversibility of the treatment chosen for this case prevailed.
The traditional lining with flour porridge is reversible because harmless materials intervene in this intervention over time. This practice has been tested in practice for a long time. It was a treatment already used in the Baroque, coinciding with the rise of painting on canvas. There are many cases of pictures, paintings on canvas, which have survived to our time reinforced with the traditional lining since the time of the old Alcázar de los Austrias in the seventeenth century.
The case in question presented a rewoven with a fine-spun linen canvas lining, analogous to the original. It must have been unbroken, a process of curing and aging of the material to make it analogous to the original. Therefore, it did not show alterations, deformations, changes in tissue tension, etc. The current problematic reason for this new treatment had to do with the reintegration of the fabric and the darkening of the surface patina of the paint, with traces of waxes and a thick layer of oxidized varnishes. And precisely a badly applied patch and above the lining had marked the front of the paint. The old grafts, many covering damage from candle burns, had moved. And some of the original fabric flaws were ungrafted and had been plastered directly onto the liner.
The state of conservation of the work and degradation of the pictorial layer demanded a joint intervention with a new lining. This old lining treatment, well executed at the time, makes it possible, due to its reversibility, to now make a new lining. And after removing the old lining, carry out a new almost comprehensive treatment, solving the defects from the beginning. The mechanical removal of the old lining is feasible without the need to re-offend with extra material, being able to remove it easily.
After the new lining treatment, it was possible to intervene with the rest of the necessary procedures, cleaning and elimination of oxidized varnishes, new grafts, coating and chromatic reintegration and final protection.
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