albumen negative emulsion
I'm going to start experimenting with dry albumen glass plate negatives in a large format pinhole camera. Due to the slow nature of albumen negatives I thought about using a small amount of sodium thiosulphate as a super sensitizer as this is used in many commercial gelatin films.
My question is: why do all albumen formulas call for sensitizing the albumen after coating on the glass? Why can't the silver nitrate be added directly to the emulsion and then coated as in gelatin?
Does anyone know of a technical reason why this won't work?
And, as a side question: can albumen negatives be developed and fixed with modern methods? D-76 is a lot easier to get and work with than gallic acid...
AFAIK, albumen is a poorer peptizing agent than gelatin is, so when you add the silver nitrate to the salt/albumen solution it will probably not form the most desirable crystals. It will probably fall out of the solution as a true precipitate. But if you want to add silver to the salt in a binder, why not just make a regular emulsion?
In any event, the thiosulfate step can take from 30 - 90 minutes at up to 70 degrees C, and this is impractical with a dry plate. It is usually done in a 'cooker' or a covered container to prevent ambient light fog and evaporation.
I'm not sure what the D76 and other chemistry would do to the albumen, but I suspect that in standard solutions it would wash off. The gallic acid would have a tendancy to harden the albumen.
So where can one get photographic quality gelatin in relatively small quantities?
I did a quick search and found some major international corps but no retail suppliers.
One of our advertisers, Photographer's Formulary, sells photo quality gelatin in small quantities.
artcraftchemicals.com sells photo gelatin as well.
Sponsored Ad. (Subscribers to APUG have the option to remove this ad.)
also bostick and sullivan (www.bostick-sullivan.com)
Let's see what I've got in the magic trash can for Mateo!
Thanks guys -- good sites! Put them all in Favorites.
To answer Photo Engineer's question -- 'why not just make a regular emulsion?'
I guess for the same reason I don't just use Liquid Light, or a digital camera and PhotoShop. I've always loved both the look of the old ambrotypes and the fact that those guys made them (literally) themselves. I most likely will end up going to gelatin just for the added flexibility, but I want to use albumen right now just so I can tell people 'I made it with egg whites'.
I came across this thread as I have decided to try to make some very old-style emulsions as an educational experiment, and the first on my list to try is albumen. I was wondering if anyone who had posted here had ended up having any success? Any tips (to do or NOT to do) would be most appreciated.
I've had success with albumen prints. Try a search in the alt process forums, and you should turn up a few threads on albumen printing.
I haven't tried making albumen negative plates, as the original poster in this thread proposes.