Reduction is a method of making prints. It is not to be confused with a particular medium: it can be employed upon stones, plates, blocks or screens in all the major ways of printmaking, indeed many successful examples can be found in them all. It differs radically from multi-block one plate! screen printing. Normally, as in. most colour printing operations, a separate surface is needed for each colour, but in this method after the edition has been printed with the initial image, more of the block is gouged or eroded away, and the whole edition reprinted once more. So it goes on, serially printing the same block in different colours with more and more of the surface removed at successive stages. So you will see that from the beginning you have to believe in it! Paper, edition size, percentage of colour and texture on the relief surface for each colour, these cannot be left to see how it goes. However once a commitment has been made, freedom from all the other inhibitors of directness associated with printmaking, such as registration and master drawing, are gone, then within these initial constraints you have the most free and direct method of all.
Raymond Higgs 1990