[rollei_list] Re: was : Agfa Scala, now : home-made B&W slides in 120 revisited

  • From: "Richard Knoppow" <dickburk@xxxxxxxxxxxxx>
  • To: <rollei_list@xxxxxxxxxxxxx>
  • Date: Thu, 2 Jun 2005 21:02:17 -0700

----- Original Message ----- 
From: "claude.eichel" <claude.eichel@xxxxxxxxxxx>
To: "rollei_list" <rollei_list@xxxxxxxxxxxxx>
Sent: Thursday, June 02, 2005 8:12 PM
Subject: [rollei_list] Re:[rollei_list] Re: was : Agfa 
Scala, now : home-made B&W slides in 120 revisited


>I am not a chemist either. It's funny to make tries and 
>"create" something.
> I'll try the Agfa recipe this evenning.
> Claude
>
  I just did a comparison of the c.1940 Agfa formula with 
the current Kodak formula.  There is less difference than 
you would suppose.
   Now, there is a big difference between the recommended 
development times for the two. The Agfa instructions do not 
give a definite time but say between 4 and 6 minutes at 68F 
(20C) for "current films", meaning c.1940. The somewhat 
milder Gevaert developer gives times for a few Gevaert and 
DuPont stocks of the time running between 6 to 8 minutes. 
Now, Kodak indicates the development time should be about 2 
minutes at 68F. This is for machine processing with 
continuous agitation.
  I note that neither the old instructions or Kodak's 
current one uses a stop bath. In fact Kodak cautions against 
using a stop bath. A wash step is used, for the machine the 
wash is 30 seconds at 68F. Agfa recommends a 10 minute 
running water wash between first developer and bleach.
  Modern films seem to develop quite a bit faster than those 
of the 1940's. This proabably accounts for part of the great 
decrease in development time but I also suspect the Kodak 
developer is more active even though both have about the 
same amount of hydroxide in them.
  Again, a caution: If you must use light fogging for 
reversal the film must be fixed after the second 
development. This insures clear highlights and makes the 
image permanent. Washing shold be done as with normal B&W 
processing. If a fogging chemical is used, or if Sodium 
Sulfide is used for second development the final fixing bath 
is not necessary.

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

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