I'm currently working on a XIX century photographic process called Anthotype. It relies on organic colored substances that fade when exposed to sunlight. For the substances I've tried alcoholic Curcumin extract and Chlorophyll. The later is incredibly sensitive to light! But this is a problem, because after the print is done I've got no way to fix it. I've read that chlorophyll degrades more on acidic conditions and even if kept in the dark. I tried treating the photographas with a weak base (sodium bicarbonate) but it doesn't seem to help. Is there a way to pr*eserve it or preserve the color?
I've also read that on museums they basically make a copper chelate with chlorophyll and that seems to help. -it preserves the green color.
Now, I don't have copper sulphate at hand. I've read it's found as "root killer" on hardware stores, but the products at my local hardware store don't list the compounds on them and also there's no root killer specifically. Is there other salts that can make a chelate with chlorophyll? I've read that zinc will also work.
Also, is pheophytin (The main chemical formed when chlorophyll is degraded) more resistant than the actual chlorophyll?