The grinding of a color is done mostly by apprentices as the time of a journeyman would be too valuable. In most cases this part of the preparation gives the greatest trouble, since the colors are seldom gotten to that fineness necessary to marbling. This is easily explained as the grinding demands practice and a certain perseverance. From the point of view that time is money, the majority of book-binders concluded to use ready ground colors and this was profitable to them as they could buy them better and finer ground and much cheaper. But, even here, we sometimes find articles, which leave much to be desired, but which, in most cases, can be used.
For fifteen years I have been carrying on the manufacture of marbling colors and must always endeavor to keep pace with the progress of the chemistry of the colors as new products are continually offered for sale superior to the old in quality and beauty.
To give to the trade an idea of the manufacture of marbling colors I will briefly describe it.
It is a well known fact that among the great number of colors produced by a factory, there are always several, which excel by their especially good quality. I selected, therefore, from among the colors of several factories, those which were especially excellent and I now control an assortment, which hardly any single factory is able to supply.
In preparing them 20 pounds are always ground at once. The color is ground upon a large marble slab with water and gall, to mineral colors the necessary glutinous matter is added and this is formed to a thick paste and then ground in the color-mill. The grinding in the mill is essential to obtain a homogeneous mass and then this paste is ground twice on a color grinding machine with three porphyry rollers in the finest possible way.
The color having been diluted is then prepared on a size, which is gotten up for this purpose and then preserved in stone jugs.
It is easily explainable, that the best results must be obtained with such a carefully and excellently prepared color, I, therefore recommend to my fellow marblers, the marbling colors manufactured by me.[A]
Before using, the color must always be well shaken and there must only be taken from the bottle enough necessary to one marbling process. The remaining portion of the color must not be poured back into the bottle, because if this be repeated several times the whole color would be spoiled by the gall.
A small quantity of, say from 40 to 50 drops of color, is sufficient for marbling the edges of even a large number of books, the colors must always be kept tightly bottled up as they may be spoiled by being exposed to the air for a longer period.