Chapter 11: Lumen and Accelerated Lumen

The so-called “lumen process,” stock silver gelatin enlarging paper exposed in a printing-out mode with no chemical development, is illustrated for making photograms and prints from transparencies. The result is usually fixed to make a permanent print, but we review the possibility of using it instead to produce a paper negative to be scanned for a digital image. The author’s accelerated lumen process is also reviewed; a solution is applied just before exposure that temporarily increases the speed at which the paper prints out. The photochemistry of this process is examined, and examples are presented. Unconventional means of exposure are described, including by a laser and by selective application of the accelerator solution. The process sometimes results in scattering colors that may depend upon the wavelength of the incident light, allowing for a kind of color photography from single exposures with nominally black-and-white emulsions.