between about 4 and 7 g l the fixer solution in the circuit gradually picked up a light yellow brown color no attempt was made throughout these trials to replenish any of the fixer additives the ph required adjustment with glacial acetic acid on one occasion again during the entire course of the trials no difference between the performance of the regenerated fixer solution or the quality of the x ray film images and those of the adjacent line using only virgin fixer solution could be detected to test the shelf life of the film treated inter alia with repeatedly regenerated fixer solution an x ray film processed with regenerated fixer solution at the end of the trials described in example 4 was subjected to the standard 34 light fastness test 34 stm 405 by the south african bureau of standards using film processed with virgin fixer solution as the control the test comprises irradiating portions of film with the uv light from a xenon lamp in a chamber at 63 u00b0 c and a relative humidity of 30 percent after about 200 hours 39 irradiation both samples started to show a very slight yellow coloration at the end of the test i e after 300 hours 39 irradiation the yellow coloring had not noticeably intensified and was similar for test sample and control the coloring was adjudged as 34 not significant 34 the sabs report described the accelerated ageing test.