In selecting an oval piece for working, care should be taken to get one without flaw. This is a difficult matter, and requires a great deal of experience. Beginners should select pieces tolerably smooth; but practised workers prefer those which are irregular in their surface, because they furnish more scope for the exercise of their skill. In cutting these, the design follows the convolution of the shell. It is dangerous to lower any one portion, because the white surface does not preserve the same relative thickness all over the piece; and unless care is taken the ground will show through. This is not a disadvantage in the ear or the neck, but would be serious if it was apparent on the forehead or in the cheek. A skilful Cameo-cutter will, however, so arrange his design as to produce the blush of the ground in such portions as to enhance the value of his work. In drawing the face, avoid, if possible, the rough, rotten-looking patches. These are signs of decay which may only be superficial, and disappear at the first cut; but, on the contrary, they are more likely to penetrate deeply, and may necessitate the lowering of the whole face before they can be got rid of altogether.
Sometimes, when the face has been modelled, and nothing remains but the finishing, a crooked line appears, which Cameo-cutters believe is caused by the presence of a worm in the early development of the shell. This is very difficult to get rid of; hence extreme care is necessary in selecting the piece for working.
A third fault is “flaking,” when, by a single cut, the whole of the forehead chips off, or half the nose disappears. There is no remedy then; the whole face must be cut in low relief, or the piece be thrown aside altogether; the latter is often the more preferable course. But all these risks are minimised by experience. Having got a satisfactory piece mounted, the Stick is held in the left hand, and the face drawn upon it in lead-pencil, a little larger than the size actually required.
If a whole shell is to be carved, care must be taken in the first instance to cleanse it. To do this, get a small quantity of muriatic acid and wash with a brush; this will bring away all the dirt; then add to some fresh muriatic acid hot water, immerse the shell for one or two minutes; then rinse the shell in cold water.
Holtzaffpel, referring to the outlining of the design, recommends that every portion be left rather in excess, so that there may be ample room for improving the outline in finishing off. Be very careful not to injure the ground, as the natural surface is superior to any that can be given artificially.
Drawing the Design.
Beginners should draw the design or figure first upon a piece of paper, or model it in clay or wax, and then draw the pattern upon the shell.
Fig. 2.—Transferring Head to Shell.
If the surface of the shell is irregular, do not attempt to make it level, but follow the irregularities, remembering that the white stratum is of the same thickness all through the piece, and that if the surface is filed down the ground will show through, disfiguring the appearance of the design, and preventing the pattern being modelled in proper proportions. When the design is settled upon, copy it on the shell with the help, if necessary, of a star, as in the head ([Fig. 2]). Draw the outline slightly larger than the design, so as to allow of the proper proportions being secured on cutting. Skilful Cameo engravers never use a pencil, but sketch the desired outline with one or other of the cutting-tools; and many of them could not draw the figure on a piece of paper which they readily cut with their tools.