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htmlguru4242
10-24-2007, 01:27 PM
If anyone's interested in looking at historic literature about emulsion making or anything from the make-it-yourself era of photography, check out Google Books (books.google.com).

I was browsing around the other day and a google books result came up in a search; i took a look around and there's all kinds of info on making collodion and gelatin emulsions, coating them onto plates, and sensitizing them with dyes, etc.

I have no idea how accurate it is, and i have no idea if any of it would be applicable or useful today, but its still fascinating.

Maybe those of us interested in making emulsions can gain some info from here?

Emulsion
10-24-2007, 04:07 PM
Thanks for that information.

If you find some specific books can you please post the links. I haven't found much with Google books as I can only see a snippit of information from the books of interest. (even if I am registered).

However I know that they have some complete books available as a download ....just haven't found any ones related to emulsions.

htmlguru4242
10-24-2007, 07:18 PM
Sure, i can post stuff.

Tip as far as the snippet views go: At the top, click "Full View"; this'll show only the books that have the full version available.


I'll assemble a list of what I've found. As I said, the stuff is OLD...

htmlguru4242
10-24-2007, 07:30 PM
Late 19th century stuff:

http://books.google.com/books?id=GKMMAAAAYAAJ&pg=PA829&dq=gelatin+emulsion&as_brr=1#PPA829,M1

http://books.google.com/books?id=63EDAAAAYAAJ&printsec=titlepage#PPA1275,M1

Some discussion of sensitizing dyes:

http://books.google.com/books?id=ZPZIAAAAMAAJ&pg=PA31

A whole manual 'Dry Plate Making for Amateurs'

http://books.google.com/books?id=mhQ4vxoiJmsC&pg=PA1



Try searching "emulsion", "dry plate", "sensitizer", etc., and see what you come up with; I've found quite a bit of stuff on everything from almost panchromatic collodion emulsions all the way through to something very similar to the "SRAD" emulsion that PE described awhile back.

The issue with Google Books is that it only has public domain books available; this means that anything past the mid 1920s is probably not going to be freely viewable; and that's the era where this stuff gets interesting ...

Photo Engineer
10-24-2007, 08:27 PM
You must remember that all of the work before about 1940 assumes you use active gelatin, but after 1940 inert gelatin is used. Active gelatin is no longer available on the open market in any photo grade.

The results are emulsions with low contrast and speed.

I am working to convert old emulsions to new methodology using modern gelatin.

PE

htmlguru4242
10-24-2007, 08:39 PM
Thanks, PE; hopefully that can be done, as it'd really be neat to see how some of these old formulas worked and looked.

As an item of curiosity: Lot's of the things I've been reading mention Ethyl Red, Ethyl Violet, and a few other fairly common, inexpensive dyes as sensitizers

Do you know anything about these, or if they can be used in a more "modern" emulsion? Because the concept of using something inexpensive is an attractive one.

Photo Engineer
10-25-2007, 07:59 AM
They can be used. I use Erythrosine and get a fine green sensitivity contrary to modern writers opinions. The technique of using these older dyes is different than what is used with modern dyes and that makes the difference.

Older dyes were often negatively charged, whereas modern dyes have positive charges. This causes the difference in methodology. This is a simplification, but gives a general idea.

PE