The patina of bronzes presents a difficulty in addition to the artistic difficulties of creating a convincing pseudo-original, difficulties common to clay, stucco, and, in fact, all faked sculpture. Patina, the nobilis ærugo of Horace, is the peculiar oxidization acquired by bronze with age. For the connoisseur, the patina is not only a part of the artistic tout ensemble of a bronze object—so much so that there are collectors more impressed by the beauty of the patina than by the artistic value of the piece—but it is the chief indication of the authenticity of the work.
According to Pliny, great importance was attached to the nobilis ærugo by the Roman connoisseurs also, especially in the case of the famous Corinthian bronze. This metal was classified into five qualities by the Roman amateur according to five different hues or patinas depending upon the proportion of gold and silver in the alloy. Roman art lovers made a regular study of bronze patina and of the composition of the bronze of art objects. The components of this knowledge were not only gathered from the appearance of a certain bronze, but by its relative weight and the odour of the metal. That the odour of an alloy should have been made a test to judge of its component parts is very possible as the smell of bronze and brass is essentially different, and there is no reason why a practised Roman nose should not have distinguished slight differences according to the proportion of the various metals in the alloy.
One reason, apart from artistic motives, why the collector gives the patina so much consideration is, as we have said, because the patina nowadays is one of the safest guides in buying antique bronzes. Whilst the artistic qualities of certain objects may be reproduced with skill or trickery, patina of a really genuine and entirely convincing appearance is supposed to be beyond the faker’s art. Our own and other people’s experience leads us to doubt this, but such, as a matter of fact, is the common belief among collectors. Faked patina, it is true, is less transparent and duller than the genuine, and it can easily be detected by shininess at the points and sharp edges of a bronze where it is difficult to fix the imitation patina, but, we would repeat, there are bronzes in Naples and some of the cities of Northern Italy that have deceived the best connoisseurs, and samples may be seen in nearly all the important museums of Europe and America. Almost all works treating specially of metal casting give various methods for obtaining a proper patina according to the different hues one may wish to give the bronze. Yet modern methods of colouring and oxidizing bronze do not seem to satisfy the antiquary and, in consequence, the faker of antique bronzes. All modern mechanical methods produce fine colouring without brilliancy, colouring that does not seem to possess the vibrant quality of old patina, oxidation that appears to be too superficial to show the depth of colouring peculiar to patina obtained by the slow process of age. To obtain such an effect the faker resorts to the most varied and out-of-the-way methods, and when possible tries to hasten the slow oxidation of age by greasing and smoking the object, putting it in damp places and treating it with acids. Often the most varied methods are used in conjunction or alternately with a patience and persistence worthy of a more honourable cause, but practised with ever-greater keenness, alas, with the promise of much gain. Some of the most successful patinas are obtained not only by duly working at the colouring and oxidation of the metal, but by composing the alloy in such a way as to favour the production of a convincing patina later on.
Naturally, the differences of the patina of old bronzes depend not only upon the various conditions to which the work may have been exposed through age, but also upon the colouring or kind of artificial oxidation that may have been given it upon leaving the foundry.
Photo
Alinari
An Imitation of Roman Work.
Latest part of XIVth Century
