In intaglio printmaking techniques an incised line is created in a surface, usually copper, to hold ink, which then can be printed onto paper. In drypoint this groove is scratched into the copper plate with a needle. The incising raises a metal burr that catches and holds the ink. The line can be varied in strength and depth to create subtle differences. With etching the line isn't scratched into the surface, instead an acid proof ground, often made from beeswax, is applied to the surface of the plate. Using a needle this is removed by drawing into it which exposes the metal. This is then dipped in acid which eats away the exposed plate creating an incised line. The longer it is left in the acid the deeper the lines will become which will make darker lines when printed.
I often hand colour my prints with watercolour, this means that no two sheets from an edition are exactly the same.
Many of these pieces are also available at The Red Dot Gallery, prices are the same.