A short description of the photogravure technique

Photogravure is a technique which was developed during the 19th century by photographers who wanted the photographic picture to be
accepted as a work of art. As a matter of fact it is a transformation from a photograph to a copper print (aqua-tint-etching) .
Gelatin mixed with potassium becomes harder in UV-light this makes it possibleto make the transformation,
more UV-light= a larger proportion of hard gelatin.

A transparent photo (positive) in absolute contact with the gelatin-/potassium exposed by UV-light creates a trace of the photo in
the gelatin. The white and light parts of the picture are also the part where the hard gelatin is thickest and vice versa.
The hard gelatin protects the copperplate from the acid.

The etching starts In the darkest part of the picture, the lightest parts comes last. The consequence of this is that the etching becomes deeper
in the darkest parts, the lighter parts becomes more shallow and this creates a continues tone scale in the plate.
In the deepest parts more printcolor is caught consequently that area of the plate become the darkest.

The copperplate has been prepared with a structure of grains in an aqua tint box. The plate is etched in ferrichloride.
The result is in fact an aqua-tint-etching but with a completely different tone-scale.

Then the plate is printed like an ordinary etching. It is possible to continue the work with the picture with copper graphic tools.
The photogravure technique is a mixture between photo and copper graphic.

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