Two-edged Backing Boards.
The backing boards may be replaned from time to time, as they become used, but boards may be had having a double face of steel to them; these may be used from either side. The edges of the steel must not be sharp, or they will cut the paper when backing. The ordinary boards may also have a face of steel screwed to them, but I prefer to use the wood—one can get a firmer back without fear of cutting the sheets.
There are several backing machines by different makers but they are all of similar plan. The book being first rounded is put between the cheeks, and the roller at the |51| top presses the sheets over. I am sorry to say that a great number of sheets get cut by this process, especially when a careless man has charge of the machine.
CHAPTER XIII. MILL-BOARDS.
There is no occasion to wait for the book to be advanced as far as the backing before the workman sees to his boards; but he should take advantage of the period of drying to prepare them, to look out the proper thickness of the board, and to line them with paper either on one side or on both.
There are now so many kinds of mill-boards made that a few words about them may not be out of place. The best boards are made of old rope, and cost about £30 per ton. The various mills make each a different quality, the prices ranging down to £14 per ton; about this price the straw boards may be said to commence, they going as low as £7, and even less.
A new board has lately appeared called leather board; it is exceedingly hard and durable. I made several experiments with this board, but up to the present have not succeeded in getting it to lay flat on the book.
Boards are made to the various sizes in sheets varying from pott (17 1 ⁄ 4 × 14 1 ⁄ 4 inches) to double elephant (40 × 28 inches). The thickness is known as 6d., 7d., 8d.; 8x, or eightpenny one cross; 8xx, eightpenny two cross; X for tenpenny. Here is a list in full of all the boards likely to be used:—|52|
