[rollei_list] Re: RPA, Efke 25, fixer with hardener?
----- Original Message ----- From: "Mark Rabiner" <mark@xxxxxxxxxxxxxxxx> 
To: <rollei_list@xxxxxxxxxxxxx>
Sent: Monday, March 30, 2009 11:42 PM
Subject: [rollei_list] Re: RPA, Efke 25, fixer with hardener?
Richard I've used hardener in the developer; Before using them in the fix. 
Sodium sulfate.
Not sodium sulfite but sulfate is a hardener you can put in many developers certainly MQ and PQ's to enable such tray development activity. 
Its in one of my main Kodak darkroom chemistry books.
Worked like a charm.
It might lower the PH but the constant way in which you're interleaving in 
the tray makes for fast development times.
Developing sheet film in racks you don't need any hardener of any kind not in your fix nor your developer in my experience - which is not small. Several hundred sheets - not big either. The racks just protect them as 
you'd expect.

Full metal rackets.



Mark William Rabiner
The use of sulfate in all solutions was common for "tropical" developing. The sulfate increases the "salt" effect which tends to reduce the amount of swelling of the emulsion but it not a true hardener because it does not cross-link the molecules. In a developer the sulfate also tends to reduce the developer activity by lowering the pH a little. This can be desirable in a high temperature developer because it increases development time somewhat. There are true hardeners that can be used in alkaline solutions like developers but they are not necessary for most routine work although they might be useful for shuffling. Most are not very good for you so you wind up using nitrile gloves. 

--
Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx 
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