Many thanks for all the help. I am a biologist, so, there's generally numerous dyes that are readily available to me. Concerning erythrosine, which one should I get:
Erythrosin B (2)
Erythrosin B (1)
Erythrosin B isothiocyanate, isomer II (1)
Erythrosin B sodium salt (1)
Erythrosin extra bluish (1)
Erythrosin yellowish blend (1)
ACID RED 51 (ERYTHROSIN B C.I. 45430) (1)
also, formalin, should I use it before coating? And would a few drops of 40% in 20ml suffice?
Also, the erythrosin, can I add a few milligrams to the gelatin (in case of powder) also before coating?
Many thanks again for the help. Also, if anyone would have the time, if one has the following stais available:
Which one (if any) you would recommend for a yellow and/or green sensitizers.
Many many thanks.
B, sodium salt, but B as a free acid will work as well.
I don't use formalin, as stated elsewhere. I use glyoxal, but either work. Formalin is faster in some ways and slower in others depending on the situation. For glyoxal, in 10% gelatin, I take commercial glyoxal solution and dilute it to 10% by taking the original glyoxal (10ml) and adding it to 90 ml of water and then use 5 ml/100 grams of 10% gelatin. That will harden paper coatings within 4 - 8 hours and film coatings in 12 - 24 hours. Formalin works faster, but keeps hardening longer.
For formalin, use about 1/2 that and make sure for any aldehyde that the coating pH is between 5.5 and 6.5. If it goes lower, allow more time for hardening and if it goes higher it will probably set up before you can coat it.
I looked at the list at that URL and got dizzy. At quick glance none of these dyes will work. Look for cyanines or merocyanine dyes. The best dyes are charged heterocycles. Chain length determines the color of the dye. As you add more methylene groups between the two charged heterocycles, the wavelength of maximum sensitivity gets longer.
Tables of them are published in Mees and James along with names and structures. I hate to scan and upload from copyright material. I'll see what I can find that is not copyright.
As for doing this, you should be able to coat and test the raw emulsion repeatably before trying spectral sensitization, otherwise it will be difficult to determine the degree of success. Remember that spectral sensitization alters blue sensitivity and emulsion contrast.
Thanks (Ron, i've got your name from other threads). Also, i've read on the chemistry of photography (i think that's the title, 1955) that you can increase the iso by putting the film in contact to acetic acid vapors, does it work? Many thanks.
The acetic acid trick isn't very good, I have heard. Never tried it.
Quinaldine Red might be a candidate. I think though it has an absorption max. around 520nm, it covers a wide wavelength range from blue to green. It has been used for silver halide emulsions.
Originally Posted by narigas2006
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I'm not a copyright lawyer (yada, yada...), but I don't believe that tables of data are generally considered copyrightable. Because they gather together data that generally exists in other places, to be 'proprietary' they have to be arranged, edited or compiled is such a way that the table itself meets the criteria for "an original work of art."
This is from the 'Definitions' section of the Copyright law:
A “compilation” is a work formed by the collection and assembling of preexisting materials or of data that are selected, coordinated, or arranged in such a way that the resulting work as a whole constitutes an original work of authorship. The term “compilation” includes collective works.