Re: How many gum layers (Re: ferri sesquichlorati)
On Oct 25, 2006, at 9:27 AM, Keith Gerling wrote:
" Otherwise, why not just start with an image, invert it and make a negative of any unknown density without a curve and keep fiddling with it until you get what you want in the print."Keith, I'm not sure it would be helpful for someone to "share their curve" since it's my understanding that a curve is specific to a specific emulsion and printing conditions. So the curve I've been developing is only for Prussian blue (and probably M. Graham Prussian blue at that) at a specific gum/pigment ratio, mixed 1:1 with saturated ammonium dichromate, and printed on Arches bright white sized with gelatin and glyoxal, under an EBV photoflood for 2 minutes, at a temperature of 60 degrees F and 75% RH, from an inkjet negative printed on the specific kind of cheap transparency I'm using (whatever it is). Any deviation in that protocol would necessitate drawing up a new curve, because the curve is intended to fit the protocol exactly.