and mordants increase the color density . I watched a program at BBC about mordant making from seashells at the shores of England. Flat bottomed boats come to the shore and sit to the ground after tidal wave goes and horse carriages carry these shells to the ships. It was one of the biggest industry in England until the 1900s. I think seashell have calcium aluminum inside and oxidised at big burning pits.
Yes , it was alum , alum trade !
Thank you for the tip .
I contacted with Eastman House , waited 4 weeks , directed to Motion Film Dep. and directed to RIT Rare books librarian and directed to retired Kodak Research Lab. member.
He says he doesnt believe to salts of sulfonic acid dye theory but inorganic pigments. He says he believes to ferro or ferri cyanides for green but no idea about Red.
He supports Magnesium Alum theory.
He says Capstaff changed the direction to cyan , magenta colors later. ps. I posted his patent numbers.
He says they were applying a bleach to BW Slide and than replace silver with pigments.
He doesnt believe to glue two films together idea.
IDK who you talked to from Kodak, but he is correct. The pigment replacement was difficult AFAIK (see my other post) and also AFAIK was never commercialized. Instead, Dye Transfer was developed.
At the end of our Azo dye work, we were using Azo dyes that formed complexes with Nickel to form very stable dyes on mordants.
look at below for sulfonic acid R G colors formulas.