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