The mechanisms of print-out in silver halide holograms are outlined and proposed methods for minimizing print-out are reviewed and discussed. Bleached holograms (transmission and reflection) were subjected to an artificial daylight source (765 W/m2 in the waveband 270 - 800 nm), for periods of time up to 15 hours. Three commonly used bleach processes were investigated for transmission holograms (rehalogenating with and without fixation, and a reversal bleach) together with some post-bleach treatments. Reflection holograms were bleached in parabenzoquinone (PBQ) solutions. A number of post-bleach (anti-print-out) treatments were investigated but none were ideal. However, a slow increase in transmission of the holograms, on dark storage, after the final print-out exposure ('print-out relaxation') was observed and rebleaching of holograms, after print-out, made them more resistant to further print-out. The influences of a multiplicity of processes on print-out and its relaxation are discussed and recommendations made for combatting the effects of print-out in bleached holograms.
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