Hello P.E. and All,
I do not know the structure of Sands SDA3057 sensitizing dye. But I do know that, when residual dye solution is left to dry on an eyedropper or beaker, it turns bright gold in color. Of course this might be organic "fool's gold". But I wonder if gold is used as a component of color sensitizing dyes. I know that at least 2 other people who are regulars on this forum now own some SDA3057 for use inj their future emulsions.