What is the point of collodion?

[Jerevan]

I know that this is really out on the fringe of emulsion making, but why does one use collodion for wet plates? What better (or different) properties does it have compared to gelatin or gum arabic?

[Barry S]

Collodion has some unique properties that make it well suited as a carrier for silver salts. It's soluble in ether and alcohol--two solvents with low boiling points and high vapor pressures. This allows the collodion to set and dry quickly. Once the collodion is set, it forms a stable permeable layer that can be sensitized, exposed, developed, and fixed. When the collodion dries, it forms a very thin, tough layer--impermeable to aqueous solutions. Collodion is also extremely sticky--it will adhere to just about any surface. Gelatin and gum arabic are soluble in aqueous solutions, so a surface coating will dry much more slowly.

[Hexavalent]

And collodion smells great!

[jnanian]

And collodion smells great!

dr hunter s. thompson has spoken

[dwross]

I know that this is really out on the fringe of emulsion making, but why does one use collodion for wet plates? What better (or different) properties does it have compared to gelatin or gum arabic?

Great question, Jerevan!

I seem to remember a story that Dr Maddox, who's credited with discovering gelatin as an emulsion base, was motivated by the smell of ether. He hated it! I've heard of worse motivations for discovery.

Gelatin dry plates were seen as a real breakthrough in photographic technology. Mostly, at first, it was about convenience. You could make the plates ahead of time, take them into the field and bring them back weeks or months later for processing. I can't even imagine how nice it must have seemed not to have to haul your darkroom every place you went. And, even with your darkroom (wagon or tent) at your elbow, in hot, dry conditions it could still be a challenge to get a plate poured and exposed and developed before the collodion dried and became unusable.

After gelatin came along, it was discovered that silver bromide could be used instead of the silver iodide in the collodion process (And my history goes way soft here. Someone who does wet plate could tell more about the details.) Using gelatin let the silver bromide, which is inherently much more sensitive than silver iodide, be 'ripened' at high temperatures for a long enough period of time that it got even more sensitive, i.e. 'faster' speed. Convenience, combined with better speed, pretty much revolutionized photography, almost literally overnight, especially when commercial manufacturing took over and photographers could buy their materials instead of having to make them on the spot. Of course, that exact artisan characteristic is most of the appeal of wet plate collodion today.

Motto: Never second guess the future, at least as far as historians and artists are concerned!

[Photo Engineer]

Or, wet plate collodion was used because it worked! It was toxic, flammable and fugitive (in terms of activity) and was quickly abandoned by adherents as soon as dry plate came along. It was never made at higher speed, nor was it made ortho or panchromatic and so it died an honorable death only to linger on by adherents who wanted to sniff ether. JK

PE

[Jerevan]

"toxic, flammable and fugitive" - in the back of my head I knew there was some hitch. Thanks for your answers.

[AgX]

Gelatin, aside of the feature of yielding storable (before and after exposing) has unique features that are important for crystal growth and sensitivity.

[jnanian]

aside from being able to be viewed as a singular item
( like a tintype/ambrotype/alumintype/keriktype/schwabtype &C)
collodion negatives can be used to reproduce positives ...
it can be and peeled off the glass substrate and is actually a sheet of celluloid film,
before collodion was identified / re-purposed for a photography the only reproducible negatives came
from the talbotype / calotype ... and even after the "wet plate age" collodion was film's first step
into being a mechanically ( or human ) reproduced positive .. non-safety film, xray film, movie film.
it was only after the fire are the cleveland clinic that safety film was invented
http://www3.gendisasters.com/ohio/27...fire,-may-1929

collodion has a lot of other uses too.
it is used in the record industry to make blanks / lacquer plates ( what first pressings are made from );
it is used in the explosives trade to make "stuff" ( made from guncotton );
fingernail polish; and "new skin"
and it still has medical uses ... and is in things like compound w. and new skin (like a clear bandage)

the whole collodion bandage thing has reminded me about people
self combusting " it happens all the time" ... now it all makes perfect sense

[Kirk Keyes]

And collodion smells great!

HMMMMmmmmm....

I love the smell of ether in the morning!