Quote Originally Posted by wildbillbugman View Post
Hello Everyone,
I do not often post on this forum because most of my experemental work these days is covered in the Silver-Gelatin Forum. I did take a workshop on Wet Pate Collodion several years ago, but did not follow through on it.
I am reading "Treatise Of Photography On Collodion" by Waldack and Neff;1856. After chapters on both Positive and Negative Wet plate Waldack adresses Dry pale Collodions. Here is where my intrest is raised. I am currently working on a panchromatic silver gelatin dry plate process. But Waldack raised my intrest when he wrote that the use of iodine salts with the bromide salts creates sensitivity to red ,yellow and amber light.
Almost all silver-gelatin emulsions contain both bromide and Iodide salts. But here the iodide increases photo-speed. It dose not yield sensitivity to green or red light. Without the adition of spectral sensitizers (specific dyes), all silver/gelatin/bromide/iodide emulsions are sensative to blue only.
My question is this. With Collodion plates,can orthochromatic or panchromatic plates be made without spectral sensitizing dyes?
My guess is "no". But I have very litlle experience with collodion, so I thought that I would ask.
Regards and thank you,
I'm not a chemist, but the bit about red sensitivity really surprises me. I will be interested to see what Photo Engineer has to say about this.