place it upon a new one. He did this with one of Raphael’s Madonnas, in the gallery of the Louvre; and the same treatment has since been extended to the ‘Resurrection of Lazarus,’ by Sebastian del Piombo, one of the pictures in our National Gallery. This process is generally accomplished as follows:—
“First of all the surface of the picture is pasted over with gauze and paper; after that the wood is made straight by moistening, or, if necessary, by making incisions with the saw, into which cuneiform pieces of wood are driven. By means of a tenon-saw the panel is to be sawn into little squares, which must be removed by a chisel, and in this way the thickness of the wood is reduced to half an inch; it is then planed until it becomes no thicker than paper, and the rest is removed by means of a knife and with the fingers.
“The painting being thus severed from its basis, it can be fixed on canvas if the priming is sufficiently preserved. In the opposite case a mixture made of chalk and glue, or something of the kind, must be put on first, and very evenly smoothed after being dry. This done the new canvas has to be fixed upon it by means of a mixture of glue, varnish, and turpentine, and the substance of the picture pressed tightly and evenly against it by means of warm irons.”[86]
[86] Liebreich.
Defects in the priming of an oil painting, when they are confined to a slight separation of the priming of a canvas, may be remedied by pouring into the gap caused by the severance a little solution of size, and then pressing the separated surfaces gently together. Slight cracks must be filled up with fresh priming.
For paintings in which the whole of the priming seems insecure, or has extensively separated from the canvas, it is recommended to remove them entirely from the old basis and to transfer them to new panels or canvas.
The property of unchangeableness, or indisposition to fade, as exemplified in the retention of its freshness of colour by a picture, is one which, it is asserted, is very much more generally met with in the pictures of the Italian,[87] and Dutch painters of the 15th, 16th, and 17th centuries, than in those of the French and English schools of the last hundred years. Opinions have been advanced in explanation of this circumstance. One is, that the older masters used pigments and vehicles of much greater purity and freedom from adulteration than the latter generations of painters; another, that they worked by a method and prepared their colours by a process unknown since their time, in fact, that they were possessed of a technical secret, which, as they never divulged it, has died with them; a third, that they had choice of many colours unknown in the present day.
[87] From the Italian school must be excepted that of Bologna.
One of the later and most valuable contributions
to our knowledge of these points has been made by Dr R. Liebreich, in his lecture “On the Deterioration of Oil Paintings,” delivered at the Royal Institution, March 1st, 1878, which also embraces the practical deductions to be drawn from the results of his investigations. The plan adopted by Dr Liebreich for unravelling the so-called secret by which the old masters so generally contrived to secure permanency for their colours was ingenious and logical; it consisted in dissecting the structure and chemically analysing the pigments, vehicles, &c., of the pictures of the pupils of the great masters, for “fortunately they painted with the same material and by the same methods as the masters, and thousands of pictures by the pupils, well preserved and in different stages of decay, may be easily secured.”