Quote Originally Posted by bart Nadeau
So is this where an emulsion starts as blue sensitive and is then made to be orthochromatic or pancromatic?
Sorry if this is an ignorant question but it must happen somewhere in the process.
Also, another question I've wondered about is making silver nitrate. If you disolved as much silver as could be in nitric acid and then air dryed it down to silver nitrate crystals would this give you good enough silver nitrate for an emulsion such as this.

bart
Bart;

Yes, the addition of sensitizing dye can make an emulsion sensitive to any particular portion of the spectrum you wish including infra-red. A raw emulsion is mainly UV and Blue sensitive.

Most silver has impurities in it that will make it unusable for photographic emulsions. It would depend on the silver and on the nitric acid. Reaction of silver metal with nitric acid, IIRC, requires red fuming nitric acid as silver is a noble metal. RFNA, as it is called, is rather hard to get and gives off very toxic fumes.

PE