Cupreatype

We use the cyanotype method, but rather than using ferrous ions to react with the ferrocyanide formed, copper plays this role, via ammonium copper citrate. The whites are less white than in Paterson's cuprotype, and the result is more pinkish. I have not found any reference to this process in the literature, so I have named it: Cupreatype Dyke and filed a Soleau envelope (Stéphane Corbé - 2026).