[pure-silver] Re: Fwd: Kentona, response from Freestyle Photo

  • From: Ray Rogers <earthsoda@xxxxxxxxx>
  • To: pure-silver@xxxxxxxxxxxxx
  • Date: Fri, 5 Dec 2008 20:32:40 -0800 (PST)

I do not know the answer, but I do know that

1. 
Warm tone emulsions often have their bases tinted with yellow or reddish dyes.

2.
Chloride emulsions had a tendency to yellow, presumably due to collodial 
silver. Things were added to controll this and modern emulsions suffer less.

3.
Develeloper activity DID have an effect upon this behaviour.

This is why I think it informative that the paper be given the tests you 
suggested.

After all is said and done, the emulsion makers know what they did to the 
paper, and they are the ones that should be answering these questions.

With this in mind, I will pass the question on, if Elias has no objection.

Ray

ps
It is interesting to determine if the yellow is a dye that can be easily 
removed, water, ethanol and methanol (try each, alone) [or, if you send me 
snippits, I will do it for you.]

or, 

if it is collodial silver, which will bleach and tone just as regular image 
silver...
  Richard's suggestion covers stuff, but if you are not that dedicated to the 
drudgery, I could do it if you send me some snippits....

Anyway, I will see if Harman wants to address this issue head on.





--- On Sat, 12/6/08, Richard Knoppow <dickburk@xxxxxxxxxxxxx> wrote:

> From: Richard Knoppow <dickburk@xxxxxxxxxxxxx>
> Subject: [pure-silver] Re: Fwd: Kentona, response from Freestyle Photo
> To: pure-silver@xxxxxxxxxxxxx
> Date: Saturday, December 6, 2008, 12:36 AM
> ----- Original Message ----- From: "Elias Roustom"
> <elroustom@xxxxxxxxx>
> To: <pure-silver@xxxxxxxxxxxxx>
> Sent: Friday, December 05, 2008 3:13 PM
> Subject: [pure-silver] Re: Fwd: Kentona, response from
> Freestyle Photo
> 
> 
> > What's worse is their solution. "If you are
> using a metol based developer,
> > try switching to a phenidone base developer or vice
> versa"
> > 
> > So it's bad in either?
> > 
> > I'm using Dektol, and I also have sprint. Is that
> the switch they are
> > talking about?
> > 
> > How critical do you think distilled water could be?
> > 
> > I don't know if this line of questioning is worth
> the effort. I have
> > 10 sheets left. I'll play with them, but I
> don't think this is a paper
> > I'm going to waste my limited darkroom time on.
> > 
> > Too bad.
> > 
> > Elias
> > 
>     Again, I'm not a chemist but have some knowledge of
> photographic chemistry. I can't understand why it should
> make any difference if a developer has Metol or Phenidone,
> or hydroquinone or ascorbic acid, for that matter. Usually
> the cause of staining in the developer is partially oxidized
> developer which can have a staining action. This can also
> happen if the developer is old and a substantial part of the
> sulfite has become oxidized. One of the purposes of sulfite
> in a developer is to prevent oxidation of the developing
> agents with the attendant generation of compounds which can
> cause staining. Similarly I don't quite understand what
> could be in tap water which would affect this unless the
> water was very dirty. Most packaged developers have
> sequestering agents to control dissolved salts, mostly
> magnesium and calcium carbonates.
>     My best guess is that something got into the emulsion
> that caused the staining after a long time. That is one
> reason I asked you to look at a sample of the paper without
> developing it. I suspect that the stain is visible on the
> raw paper. If not then fixing it out may make it visible
> since emulsion is often strongly yellow colored. If there is
> stain without development it pretty well eliminates the
> developer and water.
> 
> --
> Richard Knoppow
> Los Angeles, CA, USA
> dickburk@xxxxxxxxxxxxx 
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