The roll-up

Roll-up process - Flash animation

The application of ink after the washout is one of the critical phases of stone processing. The objective is to deposit a layer of ink on the image, exactly duplicating the visual characteristics of the original drawing. The inking procedure must be executed with care and deliberation, inasmuch as the stone is only partially desensitized by the first etch.

Assuming that the first etch has satisfactorily performed its function, the success of the roll-up is conditioned by (1) the type of ink employed, (2) the technique of roller manipulation, and (3) the control of moisture on the stone only the stiffest lithographic ink (called Roll-up Black) is used for the roll-up process. Its minimum fatty content and stiff consistency help to prevent fill-in of the partially desenaitized stone. In addition, the ingredients of the best roll-up ink are specially selected for their resistance to the corrosive action of the second etch, which is necessary for the completion of desensitilation.
The handling of the ink roller is largely a matter of individual touch. Although no two printers manipulate this instrument identically, there are general principles regarding roller operation that are essential for all successful inking techniques.

The control of moisture on the stone is vitally important. The water film lies on the nonimage areas, keeping them clean because of its ink-rejective properties, and confines the ink within the limits of the image. The stone must be kept constantly damp with a thin, even film throughout the inking. Excessive water on the stone will prevent the roller from distributing ink; simultaneously, the ink receptivity of the image will also be retarded. Conversely, if the stone becomes too dry, the ink will catch on its surface, clogging the image areas and scumming the margins.

The roller, lightly charged with ink, is passed over the work rapidly and lightly four or five times without stop- ping. Examination of the work will show that the image is beginning to receive ink in an increasing or decreasing degree, depending on its particular characteristics. The procedure of rapid rolling with minimum pressure limits the discharge of ink and enables the printer to assess the receptivity of the image to the ink. Within the period of the first few passes of the roller, the printer must determine the rolling techniques necessary for that particular stone. If ink acceptance is slow, the rolling should proceed more slowl yand with graduall increased pressure. If ink acceptance is fast, rapid rolling and minimum pressure should continue. As the image develops, the roller is recharged with fresh ink from the slab, the stone is redampened, and the rolling is continued. These. steps are repeated with periodic inspection of the work until the image is fully charged with ink and duplicates the tonalities of the original drawing. In this condition it is ready to receive minor corrections; these are followed by the second etch for the completion of desensitization.

Control factors during the roll-up

  1. If the image is smaller in either of its dimensions than the width of the roller, the rolling should begin along the smaller dimension. In this way, the critical first inkings will completely cover the image without lap marks.

  2. If the first few passes of the roller are uneven, the effect will be magnified by subsequent inkings. This is particularly true for lap marks, which are exceedingly difficult to even out once they have become established. Should this occur, the work should be washed out and rolled up again.

  3. After an even layer of ink has been established, the stone should be inked at right angles to the first inking, even if it necessitates lapping the rolling. Several passes should be given diagonally from corner to corner as well. The rolling patterns should be calculated so that the last few passes of the roller are in the same direction as the first passes. The purpose of changing rolling patterns is to permit ink from the roller to engage the ink dots of the image from all directions. Otherwise, the ink will build up along one side of each dot and will gradually distort the tonal values of the image.

  4. If the image is larger in both directions than the roller width, a lapping pattern of inking is employed. It should begin from the direction that permits minimum lapping. The inking starts with one pass of the roller on the right side, two passes on the Ieft, and returns with a single pass on the right. The ink supply on the roller is, by now, greatly diminished, so that only a little is deposited during the final pass on tle right side. This is just sufficient to equalize the total pattern. The next inking starts with a single pass on the Ieft side, two on the right side;and so on alternating the starting point. With each fresh change of ink. As this sandwiching of overlapped passes is taking place, the stone is occasionally rolled diagonally and also at right angles to the first patterns.

  5. Sometimes an image will roll up very slowly, refusing to build uo to the maximum darks. This usually indicates either that the drawing was less greasy than supposed or that some of its grease content was weakened by the etch. When asphaltum solution is ineffective, a slightly softer ink may prove successful, or the stone may be allowed to dry for a few minutes before resuming damping and rolling. Images left "open" (dry and without gum protection) for varying lengths of time will tend to darken when inking is resurned. Darkening can he controlled to a limited extent by keeping some areas of the image moist while permitting other sections to dry for varying periods.

  6. Stones that have received relatively weak etches can he overloaded with soft ink in order to modify the character of their images. For example, a drawing that appears too hard and dry can be darkened and given broader and softer overtones by overinking. During the roll-up, certain areas may be permitted to dry while others remain wet. The dry areas will catch ink and produce soft roller tones, which can be localized by the edges of the moisture film. Linear work can be given beautiful soft edges in this manner. The success of these manipulations depends on one's skill with the roller and on the weakness of tle first etch (it rnust have been weak enough to permit the ink to overcome it and form its impression in the stone). In anticipation, tle artist may wish to underetch the work during the first etch, bearing in mind that he will probably have to compensate with a stronger second etch in order to stabilize the inked image fully.