Pre-sensitizing silver halide without TEA?

Justin W · Post by **Justin W** » Wed Mar 18, 2009 3:53 pm

Howdy all!

Is it possible to shorten exposures on silver halide film without also giving the film a pre-swell?

It would be wonderful to hear of a simple bath in which I could wash my film a few hours before exposure that would make it faster...

Any such thing? And if so, how does it effect the exposure time/energy density required?

Ed Wesly · Post by **Ed Wesly** » Wed Mar 18, 2009 4:04 pm

Check out the Colour Holographics technical literature, they mention using water, or water plus TEA, but wash out the TEA so you don't have the plumping agent left behind. It did seem to cut down exposures for me about 1/4 of non-treated plates.

jean · Post by **jean** » Wed Mar 18, 2009 5:14 pm

Some mention that we can use ammonia too.

Take a look at
http://www.holo.com/holo/book/book6&7.html in the end of the page (or make a search on 'ammonia')

Hope that help.

Justin W · Post by **Justin W** » Thu Mar 19, 2009 4:46 am

Cooooool.

The plain water bath mentioned by Ed... Does this hypersensitize by means of simply washing some of the preservative from the emulsion?
I was hoping to hear things could be that simple.
Ed, when you say cut down exposures 1/4... Is that as in by 1/4 of the regular exposure time? To 1/4 of the regular exposure time would seem like an extravagant increase in speed, so I will assume you're saying reduces exposure time by about 1/4 of the original value... Still sounds like a healthy improvement!

Jean - thank you for your reply as well. If plain DI doesn't work out, I think working with some ammonia sounds a lot more do-able than getting mixed up with (pun intended) something that sounds as nightmarish as triethanolamine.

Options, options... i have options.

Nice.

Thanks, guys

Martin · Post by **Martin** » Thu Mar 19, 2009 6:14 am

Latensification might be another option. See: http://www.slavich.ru/?id=60

Ed Wesly · Post by **Ed Wesly** » Thu Mar 19, 2009 8:27 pm

It should be about 1/4 of the usual exposure. I don' know if this step washes out the preservative, it seems to revive the Colour Holographics plates after aging.

Ammonia is an alkali like TEA, so the mechanism of getting more sensitivity must be similar between the two. Maybe a chemist could explain why.

I am always sqeamish about getting plates wet before exposure; it's just another step to pick up water marks, dust, etc. The antique photographic process known as albumen printing paper recommended fuming the paper over ammonia to increase sensitivity. The books I have at my disposal don't mention the technique, but it might be something to try like putting a few drops of household ammonia in the bottom of the plastic plate box and seeing if the captured vapor adds sensitivity without needing to soak and dry. (We shall see when I get a chance to do that!) Or maybe the emulsion will just fall off the plate.

Another adventure in fuming is described in Bjelkhagen, using hydrogen gas (order me up a tank!) to sensitize Agfa 8E or 10E, I don't recall, and the book is at home. This technique has roots in astronomical photography, and where they got the idea from, who knows?

Colin Kaminski · Post by **Colin Kaminski** » Fri Mar 20, 2009 3:04 am

I hypersensitized a roll of finegrain B/W film with hydrogen. It is a fair amount of equipment.

I have sensitized with both methods Ed describes and they work very well.

BobH · Post by **BobH** » Fri Mar 20, 2009 4:55 am

I remember reading about ammonia hypersensitizing somewhere and mentioned it to Nick Phillips once, who recoiled somewhat with the exclamation "ammonia!

". I let it drop, thinking I'd just said something really stupid to God.

:naughty:

I looked it up in "Modern Photographic Processing" by Grant Haist and I'll quote a paragraph here from Volume 1, page 250:
"One property of ammonia compounds and amines is their effect as development accelerators, producing greater image density during the initial stages of development than do developers without the amine. As does ammonia, amines tend to solubilize silver from the grains of the emulsion but, unlike ammonia, amines do not as readily deposit silver on every available surface. Some of the silver solubilized by the amine may be used for physical development of the silver image, in many cases producing greater image graininess. Amines are especially usewfull for combined developer-fixers where rapid image formation is vital if emulsion speed losses are to be minimized."

The same book has a whole section on hypersensitization and latensification (pages 468 to 480). It discusses light, mercury, sulfur dioxide, vapors of organic acids, ammonia, ozone, water, and hydrogen peroxide. He catagorizes them as: light, mercury vapor, soluble silver salts, weak organic acid, oxidants (peroxides), ammonia and amines (and other alkalis).

BobH · Post by **BobH** » Fri Mar 20, 2009 5:00 am

Lumicon used to sell a hydrogen hypersensitizing kit for astrophotography, if I remember correctly. Now there's a hobby deader than holography! Silver halide astrophotography. RIP!

:whistle:

Ed Wesly · Post by **Ed Wesly** » Fri Mar 20, 2009 12:18 pm

Makes perfect sense when you spell it out: triethanolAMINE!