WHAT IS PHOTOGRAVURE?
Photogravure, also known as heliogravure and recently referred to as copper-plate photogravure, is both an intaglio and photomechanical technique. The technique combines the details of photography with densely pigmented etching inks. Using pigmented inks and acid-free pulp paper makes photogravure the most archival print technique. For photogravure, a continuous tone positive is exposed to light-sensitive pigmented gelatin tissue, which afterwards is bonded to a rosin-coated copper plate. The very fine rosin grains are the material matter of aquatint, which is key to the tone-based photogravure technique. Aquatint is a way of making tones. Despite the “aqua” in its title, the aquatint process does not involve water. It was invented in the mid-eighteenth century to simulate watercolour drawings. With aquatint, one can capture a complete tonal range from a hint of a tone to mid-tones to shadows and darks. Aquatints can be airy like those in the etchings of Paula Rego to velvety like those in the etchings of Pablo Picasso.
In photogravure, after the gelatin is developed the copper plate, with the image containing gelatin, is etched in baths of ferric chloride of different strengths. The etching commences with the extreme darks, moving through the tones to the lightest tone – pulling the etched copper-plate from the ferric chloride once the bite reaches the spectral highlights. Thereby the technique accomplishes a full range of tones and attests for a high quality original print.
The video has Craig Zammiello, from Two Palms Press in New York, demonstrating the photogravure technique. Video by MCA Australia