The reaction rates for the conversion of AgCl to AgClBr were studied qualitatively using a reflection spectrophotometric technique. The conversion rate was found to be dependent upon many factors, including the source of bromide and the presence and concentration of ripeners and restrainers. Soluble bromide (KBr) reacts faster with AgCl than does AgBr. Ripeners (1,1,3,3-tetramethyl-2-thiourea, 3,6-dithia-1,8-octanediol) greatly increase the rate of halide conversion. 4-Hydroxy-6-methyl-1,3,3a,7-tetraazaindene greatly reduces the rate of halide conversion or can completely eliminate it using either soluble bromide or AgBr as the bromide source.
Joaquin Calcines, Heather M. Dolan, Kristyn R. Falkenstern, Conor D. Kelly, Erin P. Murphy, Rosalyn L. Klinger, Bruce E. Kahn, A. Gary DiFrancesco, Richard K. Hailstone, "Silver Halide Recrystalization: I. Qualitative Kinetics for the Conversion of AgCl to AgClBr" in Journal of Imaging Science and Technology, 2002, pp 101 - 111, https://doi.org/10.2352/J.ImagingSci.Technol.2002.46.2.art00003