Digital negative :
- Negatives for collotype can be realized from digital images by printing ink jet on transparent film, without quality loss to compared with the argentic movies.
- It is a question of obtaining a photographic negative of a digital file (the image) by printing ink jet on a transparent support. The preliminary treatment of the image is made on any software allowing the regulations of contrast, inversion, curve…
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Ink jet printer Files can be the ones of the camera, or be obtained by scanning photographic pictures or argentic negatives by scan in high definition.
- The quality of the realized digital negatives depends on the definition of the images of departure and on the care brought to their processing until the printing on the transparent support, on the quality of ink and on the printer.
Négatifs argentiques :
- Negatives panchromatiques for ” contact collotype “: it is about the use of argentic photographic
Argentic negative negatives there – those same which received the direct image ( not reproduced image) while they were in the camera. Because of the size of the negative, a camera is used by the photographer who takes normally his photography, with this difference that it is necessary to return the movie into the camera, so that the side emulsion is turned to the operator. Once developed, negatives so obtained are used for insoler directly the sensitive collotype plate. The evoked reversal of movies is justified by their rather important thickness. He allows to prevent a diffraction of the ultraviolet rays which would occur during the sunstroke if the emulsion was not directly in touch with the sensitive coat of the collotype plate, and which would give a less fine image during the edition.
- Reproduction of documents: with a ” photographic darkroom ” (big camera) we use special films for graphic arts (orthochromatiques), by choosing however those in the softest contrast. They authorize an inactinique lighting during their use. If we use a panchromatic film for the reproduction of documents, we obtain only a low-contrast movie – at least too low and with difficulty unusable for the collotype.
other negatives :
- It is completely possible to conceive negatives without resorting to the photography, for example with the technique of the picture – glass which is a negative on glass or transparent movie realized manually and directly by the artist. The plate is coated with ink and sprinkled with powder of white lead. The artist draws in the hard point(headland). The track clear the mask of the glass or of translucent support. The drawing is obtained by the action of the light which gets through the support and makes sensitive the bichromatée gelatin. The edition is made as for a photography..
Collotype without negative :
- See explaining article Direct driwing on gelatin.