If it is desired, to use more colors than the four named, greater perfection in marbling is essential and it takes a perfect practical marbler to achieve beautiful products with eight colors, but practice and a zealous heart will even overcome these difficulties. The lustre of the colors is due to their combination, according to their power of spreading out and to their harmony.
Wall-paper will frequently show what beautiful and fine effects can be produced by three, or at the most four colors.
If the colors are separated by white, they develop a greater lustre, while black employed in the same way is productive of a more sombre effect.
The separation of colors by white and black is most decidedly more profitable and effective, than a marble in which the different variegated colors immediately touch each other. It is therefore advisable always to take black as the ground-color, white will be produced without adding any coloring matter whatever by the drawing of the colors with the stylus.
Black is the ground-color, upon which all the rest, blue, yellow, red are thrown; it is understood, that they must expand in the proper proportion, to produce a clear marble.
The lustre of the colors is mainly a result of white and black, which form, as it were, a frame about the other colors by their own durability.
The other colors, which we may add to the four nonpareil colors, are, different shades of red and yellow. A bottle is filled to one half its height with carmine-lake, then black is added until a very deep purple is obtained; another color is a powerful orange, which, if not on hand, can be produced by mixing red and yellow. To produce a beautiful combination use the following colors, black, light blue, orange, light yellow, purple and finally scarlet red, (a color which I have recently introduced under the name of safflower carmine) this combination of colors gives a surprisingly beautiful result. To produce the nonpareil (or comb) marble with eight colors, two more mixed colors are used, one of which serves as a shade to light blue, while the other enhances the lustre of the lighter colors. To this end, pour a little dark-blue into a glass bottle and mix it with the same quantity of green, obtaining a dark bluish-green. As a second color mix green and white until the color is pale green. To produce a desirable effect with these eight colors we must observe the following order, black, light blue, dark bluish-green, orange, light yellow, purple, pale green and scarlet-red.
In this wise numberless variations and combinations can be obtained, but it should always be taken care, that the primary colors only receive shading tones of secondary or tertiary colors. The mode of throwing the colors on the size is always the same as I described it for nonpareil marbles namely; form a ribbon of black from 4 to 5 inches in width in the prescribed way and throw the other colors into the black and at both rims of it but so that they are situated within the black. The same colors which are on one rim must also be thrown upon the other rim in the most uniform way possible. The marble therefore, before it is drawn is similar to a ribbon which has in its centre the black stripe about 2 inches wide, and on each side, a border of different colors 1 to 1-1/4 inches wide.
The more colors are used for the drawn marble, the less of each color except black should be thrown on the size. Although the colors have been adapted to each other in regard to their power of expansion before using them, it is indispensable in producing these marbles with such a large number of colors to assist the expansion of one color or the other by a few drops of ox-gall.
It is necessary to see, that the second color should not too greatly be displaced by the third, the third by the fourth, etc., because the color, which is mostly displaced would not appear in the marble at all.