Screen width

In addition to the screen angle, setting the screen width is just as important and crucial for the printed result. The screen width is the distance between the individual raster dots. The number of raster dots per unit distance is given in lines per centimetre or lines per
inch (lpi). Larger values can display finer details. 1 The risograph can also display screen widths, including frequencies, between 38 – 200 lpi (lines per inch, ie the dot density). If a smaller dot density is selected, gradients and halftones are displayed very fluidly, but the print image appears very coarse. Higher dot densities, however, appear very sharp and fine in the print image while gradients tend to be displayed in choppy colour stages.

38 lpi

Coarsest raster width setting on the risograph, possibly too coarse for fine images, perfect for displaying large-scale gradients

60 lpi

A good compromise for adjusting screen width between areal illustration and slightly coarse print image

90 – 105 lpi

Allround screen width for printing on the risograph. Almost all pictures should be displayed equally well

120 lpi

Screen width adjustment useful if less photographic and more areal images are to be reproduced

> 120 lpi

All settings finer than 120 lpi should only be used if no photographic images, but areal images are reproduced. Gradients may be displayed worse and, above all, in levels

It is imperative to test screen widths above 120 lpi before an edition is reproduced on the risograph. If you are unsure about the subject, it is recommended to increase or decrease screen widths in increments of five. If the print result is satisfactory at 105 lpi, a setting of 110 or
115 lpi can be tested to see how the print image changes to find the perfect setting for the sheets to be reproduced.

  1. Kaj Johansson, Peter Lundberg, Robert Ryberg, A Guide to Graphic
    Print Production (New York: John Wiley & Sons, 2011), 255.