Archived posting to the Leica Users Group, 2002/01/04

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Subject: Re: [Leica] freshness (was Mark Rabiner's)
From: "Don Dory" <>
Date: Fri, 4 Jan 2002 14:05:40 -0500
References: <>

Rei, the only sure test would be to create a test strip much as the
commercial labs use.  First frame blank, second frame gray card exposed per
the meter, third frame minus three stops, fourth frame at plus five stops.

To make this work you would have to create a standard set to compare with
known good chemistry or from a well set up commercial lab that runs
commercial test strips.

The first frame tells you if your fix is any good or whether there is some
source of dichroic fog in the system.

The third frame tells you the speed point of the process.   This needs to be
looked at in conjunction with contrast as if this point rises as well as the
middle gray then contrast stays the same but everything is overdeveloped or
the fix is going south which you can tell from the blank frame.

The second frame minus the third frame tells you the contrast index of your
system.  If the developer is just going south you will see it in the
contrast assuming the FB + fog stays constant.

The fifth frame indicates ability to create dMax, this would be important if
you were experimenting with higher dilutions.

All of the above implies the possession of a densitomiter or access to one.

E-mail me if you have any questions.

Don Dory

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In reply to: Message from Rei Shinozuka <> ([Leica] freshness (was Mark Rabiner's))