I've just started processing POP as a way of getting into alternative processing, the eventual goal is to be able to make daguerreotypes; my question- how long does the gold chloride/ammonium thiocyanate combo last once mixed? I see that the two individually last at least as long as the toner, but does the mixture decompose? Thanks in advance! JD 2001 Moto Guzzi V-11 Sport 1999 Triumph Trophy (shop bike) 1200