TROUGHS.
The troughs should be made of wood, perfectly flat and smooth at the bottom, and of sufficient thickness to keep them from warping. They should be about two and a half inches deep inside, and about two inches larger than the sheet of paper you intend marbling, or your edges will be imperfect. There should be about three inches parted off on the right-hand side by a sloping partition, which should be about an eighth of an inch below the sides, that the waste may be skimmed over it without running it over the top. The whole should be perfectly level and true; and, if the joints are stopped with white lead, be sure it is quite dry and hard, or it will entirely spoil the solution, and will fill the pattern with white.
FRENCH OR SHELL MARBLE.
To commence with the easiest and most common kinds of marbled papers:—the colours being properly ground, and the trough placed on a level table or fixed bench of convenient height, with some feet of spare room on each side, place the pots containing the colours on the right-hand side, and the paper or books to be marbled on the left. Let there be a small brush in each of the pots of vein-colours, and a larger one in the last or body-colour. Have a small iron rod or bar about twelve or fourteen inches long, placed so that you may be able to take it up when required with the left hand. Fill the trough to about one-half or three-quarters of an inch from the top with the solution of gum-tragacanth and flea-seed, as previously described, and proceed to mix the colours.
For convenience of reference, the various patterns described and processes employed will be numbered.
No. 1.—large brown french or shell, with three veins, viz.: red, yellow, and black.
Mix together ox-gall and water in the proportion of one-eighth of the former to seven-eighths of the latter. Mix the vein-colours with this mixture, putting in a little at a time, and gently stirring it about with the brush (but be careful not to make it froth by too rapid stirring) until you arrive at the proper consistence, which must be ascertained by sprinkling a little colour on the solution in the trough. If the colour sinks, and does not spread out, add a little neat-gall; but, should it spread too far and open too much, mix a little more colour with water only, and put it to that which spreads too much.
The brown will require more gall, less water, and a few drops of the very best olive-oil, which will cause it to form itself into rings or shells as it falls on the solution in the trough. This colour will require to be thicker than the vein-colours, and, when thrown or sprinkled, should drive or force the other colours into the form of veins. By increasing the quantity of gall in the last colour, it will bring the veins to almost any degree of fineness; but there is a point beyond which it is not advisable to go. If the brown does not shell enough, but forms in holes, add a few more drops of oil, and well mix it; but if there be too much oil it will spoil the effect of the shell altogether, which cannot be counteracted in any other way than by mixing some more colour without any oil, and adding it thereto.