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Overexposure A Negative Will Reverse: At gross overexposure a negative will reverse to a positive. Direct exposure to the sun will often produce a transparent disc in the negative, which will appear in the print as menacingly black. Hence this reversal of tones is known as solarization. Because of this phenomenon the skies in wet-plate landscape negatives were not uniformly black, but had patches of low density that gave a mottled appearance to the print. Consequently they were generally retouched around the contours with opaque paint and the remaining sky area was protected with a paper mask.The negative image was appreciated for its own sake. As Moholy-Nagy wrote, "The transposition of tones transposes the relationship, too."8 The unreality of the negative throws emphasis upon shapes and contours not usually seen. The phenomenon of edge reversal, known to scientists as the Sabattier effect, was used as a plastic control, particularly by Man Ray. When a sensitive emulsion that has been developed, but not fixed, is exposed to naked . light and developed again, the image shows a reversal i tones wherever there is a sharp edge. A print from sue a negative has its contours rimmed with black lines. Tl process is generally known in artistic circles as solariz, tion, although that term is reserved by scientists for somewhat similar phenomenon of edge reversal caused b gross overexposure, particularly noticeable in daguerrec types and platinum prints.
Boats are shown port side to the piers; for the reverse condition, simply reverse the rudder orders but maintain the same engine speeds and directions. |
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