This is a process with a sponge, charged with the black or the brown liquid, dabbed on the calf either all over the cover or in successive order. Give the proper preparation to the calf, and be very careful that the ground tint of brown is even. Take a sponge of an open nature, so that the grain is pleasant to the eye; fill it with black, squeeze out again, and dab it carefully over the calf. Repeat the operation with another sponge charged with brown. Cats' paw, French dab, and other variously named operations all emanate from the sponge. When done properly, this has a very good effect, and gives great relief to the eye when placed with a number of other books.
All marbles and sprinkles require practice, so that a first failure roust not be regarded with discouragement. When one's hand has got into the method with 2 or 3 colours, it is astonishing how many different styles may be produced. In all this manipulation, a better effect is obtained if a yellow tint is washed over the leather after the sprinkle or marble has been produced. Again, by taking coloured calf and treating it in the same manner as white, some very pleasant effects are brought out; and when the colours are well chosen the result is very good. Take for instance a green calf and marble a tree upon it, or take a light slate colour and dab it all over with black and brown.
In all operations with copperas, care must be taken that it does not get on the clothes, as it leaves an iron stain that cannot be easily got rid of. Keep a basin for each colour, and when done with wash it out with clean water. The same with the sponges : keep them as clean as possible; have a sponge for each colour, and use it only for that colour. A piece of glass to put the sponges on will be of great use, and prevent the work-table or board from catching any of the colour. A damp book or damp paper laid on a board that has been so stained will most probably be damaged, even though it has waste paper between the work-board and book. No amount of washing will ever take away such a stain.
When the book has been coloured, the edges and inside are blacked or browned according to taste, or in keeping with the outside.