Ok, here is an update on chlorophyll supplied courtesy of Mark Osterman.

In the Photographic News, 22 June, 1888, an early report is given that plates can be sensitized by chlorophyll. This work was by Ives and also by Abney. No methods are described, nor are results, merely that it has been achieved and was done by bathing the plates in alcoholic chlorophyll.

In the textbook "Collodion Emulsion" by H. O. Klein, he describes the same work with much more detail including wedge spectrograms. He calls chlorophyll remarkably unreliable but good when it works. One problem is that due to the spectrum of chlorophyll, it can cause up to 5 peaks of sensitivity in the emulsion, and can actually increase blue speed. In fact, the increase in blue speed must be taken into account in order that one fully recognize that any red speed has been achieved.

The stability of chlorophyll solutions is not commented on, but the implication is that it varies depending on source and on keeping conditions. One report says that the solution was stored over zinc powder to improve stability.

All refer to it being best used by bathing dry plates in a solution of chlorophyll and then redrying the plates before use. They also comment that the sensitized plates keep better than unsensitized plates. No data is given on that.

PE