It has been found that good card-board sometimes answers a better purpose than the felt-cloth, in making both the transfers. It is, therefore, suggested to all to try it; but, where card-board is substituted for the felt-cloth, it is obvious that the press and rollers must be true, and work with great accuracy.
In making “vignettes,” twenty-five or thirty grains of chloride of barium may be added to every ounce of gelatine employed in the gelatine solution, which, on coming in contact with the tannin solution, will be converted into sulphate of baryta, and will give more clearness to the white background.
It is a good plan, though not very important, to filter the sensitizing solution.
The solution of gelatine should be filtered, while hot, through fine linen cloth.
It is best to make the first transfer, and develop the prints, soon after lighting, otherwise, they may sometimes become partially or wholly insoluble. As a general rule, the tissue may be lighted in the morning and the pictures developed in the evening; but, occasionally, from some unknown cause,—it has been known to occur but once in two years—the tissue, after having been lighted under a negative, will become insoluble if kept too long before being transferred and developed.
The last transfer may be made by pulling apart with the fingers, without the application of “transferring solution” or benzine, if the prints are allowed to dry twenty-four hours after the last pressure.
The clothes-pins used should always be clean.
The tissue is better dried quickly, but artificial heat must not be used to hasten it. Hang it, if possible, in a draught of air or well-ventilated room.
