Wet Plate question

hi wet platers

im not a wet plateer ( yet ) and i had a question for folks who are doing it now and might be able to help me.
this isn't really my question but as you know i sell silver recovery stuff and someone emailed me a question i couldn't answer. people usually email me regarding KCn and the manufacturer of these devices says that they won't work with
that sort of fixer .. but i recently got an email from someone who uses plain old hypo and i wasn't sure what to say.
for fix she uses sodium thiosulphate mixed with water as a fixer,
the collodion formula is with potassium iodide and potassium bromide,
and a iron(II)sulphate developer So... the silver on the plate is in the form of silver iodide.

is the waste in the fixer pretty much the same waste that is in there when making a paper or film (modern) print/negative?
with a trickle tank the target ph has to be about 5-6, does this change when using silver suspended in collodion?

thanks !
john

[edited per poster request—mod]

From experience I used plain hypo for fix and rannplates through it till it slowed. There was always a black residue in unshaken bottles, so I guess a lot of silver was in there. The purpose of the bath is double decomposition of potassium iodide and bromide into sikver iodide and bromide. The collodion substrate does not absorb any compounds. All the action takes place on the surface. This action relates to the state of the collodion surface. It must not be fully wet or fully dry to allow these reactions. Hope this helps. Personally I never bothered with silver recovery. I done ok selling 1/4 plates for $45 when it took 9 cents in materials per photo.

hi ray
thanks for the info. im a bit confused still, but its a start
that's pretty good profit
john

jnantz said:

is the waste in the fixer pretty much the same waste that is in there when making a paper or film (modern) print/negative?

Click to expand...

I'd say so, yes. It'll be quite similar to used film fixer, I think. Most collodion recipes I've seen use quite a bit more bromide than iodide, BTW. I've experimented with it some time ago and found a ratio of 83% bromide and 17% iodide worked quite well, although most recipes call for more iodide than that. I found very little if any difference with a higher percentage of iodide in image characteristics when modifying the poe boy recipe than the indicated 17% - but with only 17% iodide I found there was virtually no precipitate in the collodion mix. But...that's a little off topic, sorry.

Edit: not only off-topic, my memory failed me as well. The formula I tried was in fact 17% bromide and 83% iodide. I checked my files and I noted a few formulas that I compared, at least on paper, and the bromide:iodide ratio varied from 33:67 to 52:48, but most are around 30-40% bromide and the remainder iodide. This is the molar ratio, so not the weight of bromide/iodide or their respective ions, but based on moles to get rid of the effects of variations in molar mass.

thanks for your help !