Introduction

Photogravure
In the late 19th and early 20th centuries the process of photogravure on copper plates captivated the leading lights of “pictorial” photography. Alfred Stieglitz, Eduard Steichen, Alvin Langdon Coburn, and later the 'straight' photographer Paul Strand, all valued the process for its rich, velvety tones. Many of the images in the volumes of Camera Work, Stieglitz's seminal publication, were produced as photogravures, including a substantial body of plates made by Glasgow's J. Craig Annan. In his own work Craig Annan pushed the medium towards pure printmaking, manipulating the copper plates as with an etching, a direction possibly influenced by his friend and etcher D.Y.Cameron. Together they travelled to Europe, Cameron making etching plates, Annan taking photographs which he subsequently printed as photogravures. It is the works of these past masters of the medium and photogravure's link with printmaking that drew Harry Magee to the process.
 
   

Photopolymer gravure

Today it is not necessary to work on copper plates since photopolymer plates give an equivalent result. They have the benefits of 'etching' in water without hazardous chemicals and depositing inert residual waste material, rendering their use environmentally friendly. The process combines traditional hand-printing techniques with contemporary commercial printing-plate technology.
 
   

Photopolymer refers to the plastic coating where the image is formed on the plate.
 
   

Gravure is the generic term for the way the plate is printed. Unlike relief printing, where the image is printed from ink on the raised areas of a plate, in gravure the ink forming the image is held in lines or areas which are recessed below the top surface of the plate. Examples of traditional gravure printing are etching and engraving.
 
   
A photopolymer plate consists of a layer of soft plastic bonded to a support sheet, in this instance thin steel. The plastic layer is treated by the manufacturer to be light sensitive and can be selectively hardened by exposure to UV light. If then a plate is exposed in contact with a film positive of an image, the plastic is hardened by the passage of UV light through the transparent, non-image areas of the film but remains soft where the light has been blocked by the solid, black areas of the image. A second exposure of the plate to a random dot screen creates a pattern of hardened dots over the image.When the exposed plate is washed in water, the soft unhardened plastic is dissolved away, leaving the form of the image recessed between hardened dots. This recessed surface holds the printing ink which is transferred to paper by pressure in an etching press.
 
   
The photopolymer gravure process

 
   
Making the film positive
The process requires a film positive of the image at the size of the finished print. The density of the positive must be manipulated to match the exposure range of the plate. Rather than assessing the positive by viewing on a lightbox, a better impression is given by viewing the positive laid on a piece of white paper.
    Viewing the film on an opaque white background.

Exposing the plate
The positive is placed in the exposure unit and the plate laid on top, with the light sensitive polymer surface in contact with the film. The exposure unit is closed and the vacuum pump switched on to ensure close contact between film and plate.
 
    Placing the plate on the film positive in the exposure unit.

After an apropriate exposure to the unit's UV light source, the film is replaced by a stochastic* screen and the plate given a second exposure. The stochastic screen exposure creates tiny random shape cells over the image which will hold the ink when the plate is developed.

*Random dot
 
    Placing the plate on the stochastic screen in the exposure unit.

Developing the plate
The plate is developed in tap water at 23ºC by rubbing gently with a sponge until all the unexposed polymer is dissolved, leaving the image as a series of tiny cells recessed in the plate surface. The plate is gently dried in a warm air flow and given a final exposure to UV light to harden up the plate for editioning.

 

 
    Developing the plate in tap water.

Inking and printing the plate
The plate is printed in the same way as a conventional etching plate. The surface of the plate is completely covered in ink of a chosen colour and then wiped with a series of three tarlatan cloths, each cloth cleaner than the previous. When all the ink has been wiped from the surface of the plate the remaining ink held in the recessed cells in the plate represents the image. This ink image is transferred to dampened paper by pressure when the plate and paper are passed together through the printing press.
 
    Inking and wiping the plate.

 
    Removing the paper after printing.

 
   
Photographs by Roger Farnham copyright © 2009 Roger Farnham
 
   
 
   
Links
Copyright © 2009 Harry Magee