Duotones first showed up at the start of the twentieth century and became common by the 1930s. This new development-the duotone-appeared in art books and other expensive publications where image quality was the first concern. The second set of dots in gray ink, even though they were pale, added body to the black parts of the picture and made the areas of middle and light values much smoother. There are difficulties faced in carrying out this variation through mechanical means, with no assistance from the mind of such craftsmen as the engraver who made this block. When these small marks cover a large percentage of the paper surface the tone appears dark when they are small or widely separated, that part of the picture looks light. The wood engraving we see here achieves this through an incredibly refined set of hand-cut lines. The solution to this problem has always been to break the picture up into small particles and to vary the size or number of those particles to emulate tone. Black ink is always black-it either goes down on the sheet and makes a black mark or it is not there and the paper is white. The fundamental problem is that photographs have tonal gradations that ink, when printed by relief or planographic processes, does not.

There are various ways in which this translation has been done and many challenges that have so often led the process astray. To this day the task of converting a photograph into ink is fraught with problems-a seemingly simple chore, it almost never turns out correctly.

Intaglio printmaking definition