The colours, having been well ground, are mixed with paste and a little oil, or glaire and oil. Then, with a sponge or brush, colour the whole of the edge. In colouring the foredge, the book should be drawn back so as to form a slope of the edge, so that when the book is opened a certain amount of colour will still be seen. It is often necessary to give the edges. 2 coats of colour, and the first must be quite dry before the second tint is applied.
A very good effect may be produced by first colouring the edge yellow, and when dry, after throwing on rice, seeds, pieces of thread, or anything else according to fancy, sprinkle with some other dark colour. For this class body colour should always be used. This may be varied in many different ways.
The edges of marbled books should correspond with their marbled ends. In London, few binders marble their own work, but send it out of the house to marblers, who do nothing but make marbled edges and paper. It is a process that may seem easy, but is very difficult to execute properly, and it costs but little to get it done.
The requisites are a long square wooden or zinc trough, about 2 in. deep, to hold the size for the colours to float on; about 16-20 in. long and 6-8 in. wide, will probably be large enough. Various colours are used, such as lake, rose, vermilion, king's yellow, yellow ochre, Prussian blue, indigo, some green, flake white, and lamp-black. The brushes should be of moderate size, and each pot of colour must have its own brush. Small stone jars are convenient for the colours, and a slab of marble and a muller for grinding them. The combs may be made with pieces of brass wire about 2 in. long, inserted in a piece of wood; several of these will be required with the teeth at different distances, according to the width of the pattern required to be produced. Several different sized burnishers, flat and round, will be required for giving a gloss to the work.
The first process in marbling is the preparation of the size on which the colours are to be floated. This is a solution of tragacanth, or, as it is commonly called, "gum dragon." If the gum is placed overnight in the quantity of water necessary, it will generally be found dissolved by the morning. The proportions can easily be learned by experience; the solution must be filtered through muslin or linen before use.
The colours are ground on the marble slab with a little water, as fine as possible; move the colour from time to time into the centre of the marble with a palette knife, and as the water evaporates add a little more. About 1 oz. of colour will suffice to grind at once, and it will take about 2 hours to do it properly.
Having everything at hand and ready, with the size in the trough, and water near; the top of the size is to be carefully taken off with a piece of wood the exact width of the trough, and the colour being well mixed with water and a few drops of ox gall, a little is taken in the brush, and a few very fine spots are thrown on.
If the colour does not spread out, but rather sinks down, a few more drops of gall must be carefully added and well mixed up. The top of the size must be taken off as before described, and the colour again thrown on.
If it does not then spread out, the ground or size is of too thick consistency, and some clean water must be added, and the whole well mixed.
If the colour again thrown on spreads out, but looks rather greyish or spotty, the colour is too thick, and a little water must be added, but very carefully, lest the colour be made too thin. If the colour still assumes a greyish appearance when thrown on, the fault lies in the grinding, and it must be dried and again ground;
When the colour, on being thrown on, spreads out in very large spots, the ground or size is too thin and a little thicker size should be added.
If the colours appear all right on the trough, and when taken off on a slip of paper adhere to it, the size and colours are in perfect working order.
The top of the size must always be taken off with the piece of wood before commencing work, so that it be kept clean, and the colours must always be well shaken out of the brush into the pot before sprinkling, so that the spots may not be too large. The marbler must always be guided by the pattern he wishes to produce, and by a little thought he will get over many difficulties that appear of greater magnitude than they really are.
The size is first sprinkled with a dark colour, termed the "ground colour"; then follow the other colours, bearing in mind that the colour which has most gall will spread or push the others away, and this colour should in spot marbling be put on last.
With very little variation all the other kinds of marbling are done; but in every case where there are more books or sheets of the same pattern than the trough will take at once, the same order of colours must be kept, and the same proportion of each, or one book will be of one colour and the second entirely different.
The colours are thrown on as before, but as fine as possible. Then if a piece of wood or wire be drawn backwards and forwards across the trough, the colours, through the disturbance of the size, will follow the motion of the stick. The comb is then drawn the whole length of the trough in a contrary direction. The wire in the comb will draw the colour, and produce what is termed " comb " or "nonpareil" marble.
The ground colour is thrown on rather heavily, the others lighter, and the wavy appearance is caused by gently drawing the paper in jerks over the marble, thus causing the colour to form small ripples.