From: zrepachol@cc.curtin.edu.au
Subject: Re: B/w papers and developers (longish)
Followup-To: rec.photo
Organization: Curtin University of Technology
Date: Wed, 6 Jan 1993 18:09:15 GMT

In article <b4R.03cic7zo00@amdahl.uts.amdahl.com>, bjs@uts.amdahl.com (Barry Sherman) writes:
...
[ test info deleted ]
> I could detect no significant difference in color (warm tone or cold tone) in 
> the test strips.  Probably color would be more noticible in a real print,
> though.  But I think that the obvious conclusion is that there is no
> practical difference between these three developers.  This is somewhat 
> surprising.  I'd expected fairly significant differences in contrast and
> density.  But the results were so similar as to be indistinguishable to
> the naked eye.  And hardly distinguishable to the densitometer.  When I
> finish the print that I'm currently working on I think I'll try developing
> versions in each of the developers to see how/if they differ in the more
> subtle arena of a real print.
> 

Ilford Multigrade FB? well not a big surprise. Most manafacturers have
'squashed' the contrast index of their papers flat as a tack nowdays. Infact,
in the data sheet Ilford mention that you can develop for 35 sec instead of 60
for overexposed prints. This is a real pain if you NEED to fiddle the contrast
for a print. I am printing some TMZ @50K, that needs about a grade 00000 paper!
However, last night the guy I bought an enlarger from gave the 10yr old 2 boxes
of Kodabromide, F-2 and T-2. The price on the box is $3.62!! 100 postcard MG III
is $20+ now. With luck, the contrast on this stuff will have died.

> And in addition, since I'm already flapping my gums, so to speak :-), I've
> been having good success using a "kinda pseudo-replenishment" scheme with
> b/w paper developer.  I like to use largish amounts of developer in largish
> trays and really can't afford to be throwing out a gallon or so of working
> strength developer at the end of each printing session - 3 or 4 nights a week
> when I'm doing b/w.
> 
> I've been measuring the volume of developer after each session and have found 
> that the double-weight fiber-based paper that I use soaks up a very significant
> amount of developer.  A session in which I develop 15-20 or so 8x10's may 
> deplete the volume of developer by 8 ounces or so.  If one is re-using the
> developer this can significantly reduce the volume of chemistry available
> after only a couple of sessions, compounding the deleterious effects of
> developer exhaustion.

About 160 in^2 per oz.  Seems a 'normalish' type replenishment rate to me. You
may care to try a fixed schedule, and see how it goes.

Developer 'exaustion' is mainly caused by, 1) increased Br- concentration
causing greater restraining action. 2) reduced dev agent plus decreased concentration
of developer due to oxidation, both by the halides and air, reducing the activity
of the developer. pH change is another factor.

In Barry's case, the carry-over is removing both bromide, and exausted developer.
The fresh solution is mainly supplying buffer and dev agent. Let me take a punt;
The developer you are using has a highish bromide conc as a restrainer, and is
moderatly alkaline, ~pH 9-9.5? probably uses carbonate as a buffer. Any one
know the formulation who can check.

The nasty to watch out for is 'squeezing' the developer: pH up, Br- down, dev
agent down, activity about constant. Them the last of the dev agent is consumed.
Bang, instant death. You may try about 1 oz per 80 "2, or if you mix your own,
cutting the bromide to 1/2 the formula for replenisher.

~Paul

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