Tin-foil is most useful for rapid impressions, especially from a fragile or delicate object. The thinnest should be used, such as is wrapped round chocolate. To preserve the form of tin-foil it may be squeezed into place with a back of beeswax, and so form a facing to a wax mould for casting a plaster positive. Or it may be pressed alone (forcing it on with soft indiarubber or cotton wool), and then floated, back up, on water, while blazing sealing-wax is dropped into it to form a backing. This mode is very handy for coin impressions, which will travel safely in this form and look well. For round objects, such as cylinders, a tin-foil impression should be made, beating the foil in with a soft tooth-brush; then the foil is to be uncoiled by rolling it upon wax so that the curve is removed without flattening the impression; it is then ready for a plaster casting, giving a flat cast of the round cylinder. In all cases thin gold-foil would be far better than tin-foil; and such an impression might even be preferred to the original object by some Oriental officials.
Drawing.
Drawing is still the main resource for illustration, although photographic processes occupy so important a place. Hand-work is essential for plans, it is the more useful method for inscriptions, and it is the more convenient method for most small objects. There is generally some interpretation needed, to show details which could not possibly all be visible in one uniform lighting, as in a photograph; and this can only be done by drawing all that can be seen in varying lights and aspects. Another superiority of outline drawings is that they are far more easily looked over and referred to than a much less distinct photograph. And lastly, they cost a third or a quarter of the amount for publication. The proper scope of photographs is stated in the next section.
As drawing is almost always to be reproduced by photolithography, or by zinc block, it is essential to have it entirely in full black and white without any grey or half tones. Hence the contrast should be kept as strong as possible; and only China ink of full blackness should be used for fine lines. In wide, coarse work, as full-sized inscriptions from walls, a common writing-ink evaporated to denser quality may be used. Ebony stain, which some use, has the disadvantage of spreading badly if it chances to be wetted. A smooth, glazy-faced paper is good for fine lines, and does not rag up under the pen. Cardboard is pleasant to use, but is awkward to send by post; whereas paper drawings roll up safely in a tube.
A cardinal rule in drawing is that the finest line should come out to 1/300 inch when the subject is reduced to the plate size. Thus a drawing to be reduced to ⅓ by photolithography should have its finest lines 1/100 inch thick. This line of 1/300 inch is the finest which is safe not to break up in reproducing; and of course it spreads a little in the printing. For very slight shade lines rather thinner lines may be used, as it is no disadvantage if they should break.
It is very desirable to have similar objects all reduced to the same scale. For pottery ⅙ is a convenient reduction; for stone vases ⅓; for metal tools and small objects ½. The drawings of pottery and stone vases are easiest to do on scales ¼ and ½, as the measured diameters have to be laid off as radii from the axis, needing halving throughout. The further reduction is done when photographing for the lithographs; and it is always best to have such a reduction to ⅔, if not to ½, of the size of the drawing, in order to make it come out more delicate than the hand-work. A very useful system for recording groups of small objects, especially such as are found together, is to lay them out on a sheet (say double the plate size), as arranged for the plate, and then run a pencil round the outlines, and add as much detail as may be needful to explain the objects; thus a pictorial inventory is made quickly, and is far more useful and easier for reference than any written inventory ([Fig. 35]). The pencil should have the wood split off one side of the lead, and be sharpened by cutting to a chisel-edge on the opposite side. Thus the point is vertically under the guiding side; and when held carefully upright, outlines can well be run from surfaces half an inch or even an inch above the paper. The size of the sheet will, of course, depend on the amount of reduction intended. For numbering the figures printed numbers can be gummed on to the drawing.
Fig. 35.—Part of an inventory sheet, recording pieces of ivory carving, 1:3.
For vases, block tints are more satisfactory than outlines. So the drawing can be filled up with a wash of ink. Or if section lines are wanted it is best to draw the section line, and block out the ground outside of the vase, leaving the vase white on a black ground; then have this reversed, black for white, in the photolithographing. The vases may be printed in any colour which is suitable.
