From: Istvan Bibo (bibo969@hotmail.com)
Date: 11/20/00-07:21:52 AM Z
>From: Tadeuz Jalocha <tjalocha@netexpress.cl>
>Reply-To: alt-photo-process-l@sask.usask.ca
>To: alt-photo-process-l@sask.usask.ca
>Subject: Re: direct positive
>Date: Fri, 17 Nov 2000 11:30:58 -0400
>
>Hello Bob and Istvan
>
>Bob, exactly the reasons you give are the ones because i´m starting to
>like positives. For alternative processes we generally need large
>negatives. I only need to enlarge my positive, and voilá; a big neg. Of
>course, you´ll need some care with the contrast, but with Kodak EIR-7
>for the neg i get lovely results.
>
>Istvan, there goes a formula i found in the net.
>It gives me full speed with Kodak T-Max 100 ( i can´t say anything about
>other films because it's the only 4x5" B/W material i can get here )
>Border density: 3.0D
>Highlights: 0.1D
>What i like about this formula, is that it uses Hypo rather than the
>very messy thiocyanate.
>If you like a thiocyanate formula, try Kodak D-67 (Not D-76!)
>
>1: FIRST DEVELOPER
> Water at 125 deg. 750 cc
> Metol 2 grams
> Sodium Sulfite, Anhydrous 100 grams
> Hydroquinone 5 grams
> Sodium Carbonate, Monohydrate 60 grams
> Sodium Thiosulfate, Pentahydrate 16 grams
> Potassium Bromide 4 grams
> Cold water to make 1 liter
>
>USE ONCE AND DISCARD.
>The original formula says 10 min @ 20 Celsius
>
>I develop 6 min 7seconds @ 24 Celsius in a Jobo Processor ( Draining
>time not included! )
>This First developer is critical! I get a huge variation with only some
>seconds more or less.
>
>2: BLEACH
> Potassium Dichromate 9.5 grams
> Sulphuric Acid 12 cc
>
>Stock formula:
> COLD!!!! Water 750 ml
> Poassium Dichromate 100 gr
> Sulphuric acid 100 ml ( add SLOWLY acid to water , please be
>careful )
> Water up to 1000 ml
>
>Dilute 1+19 for use
>
>I Bleach 3 minutes with the second formula. You may replace Dichromate
>with Permanganate, wich is less toxic, but costs more. Be VERY careful
>with this second stock. This is diluted sulfocromic mixture, it eats
>anything organic away like almost nothing else! See other postings about
>Dichromate to get a picture about this compound.
>
>
>3: CLEARING BATH
> Water 1000 cc
> Sodium Sulfite, Desiccated 50 grams
>Agitate for 1 minute.
>
>-------------
>You may alternatively Sepia tone the Positive at this stage. ( No
>previuos Light exposure needed in that case)
>
>Kodak T-19:
>Sodium Sulfide 20gr
>Water up to 1000ml
>
>2 min. Take care, this may soften your emulsion exessively!
>
>After Sepia tone, no fixing is necessary.
>------------------
>
>
>Reexposure to light.
>I use a 1000w light for a minute or so. Probably overkill. In a
>Translucent Bowl filled with Water.
>
>Second development
>I use Tetenal Neopress HC 1+31 for 7 min @24 Celsius. ( The only use i
>found for this #%$"%$ developer )
>
>Fix and wash as usual.
>
>
>bmaxey1@juno.com wrote:
> >
> > >>Is there a feasible procedure to develop my black-and-white negatives
> > (Agfa
> > >>APX 25)to BW positives?
> >
> > Formulas abound for doing this, but I prefer not to. The reason is
> > simple: once I have reversal processed the film, they are forever
> > positives. If this happens, making black and white prints becomes a
> > chore, because I then have to create a negative from them, creating
>extra
> > work and a loss of quality.
> >
> > Bob
>
>
Hi, Judy, Tadeuz, Bob,
Thanks for the comments. Tadeuz was right, I need the positive to produce
large negs for alt. processes while elliminating the need for internegs. I
have come across direct positive formulae in books, but they seemed
complicated, long and producing results of doubtful quality. The formula
cited by Tadeuz confirms me that there are no quick-and-easy procedures. The
hypercritical 6 minute 7 second development time he cites is deterring!
I have been making large negs from color slides,which are more expensive,
granier and more contrasty than the Agfa 25 B&W negs (developed in a soft
working developer) that I currently use for B&W prints. A good B&W psitive
would have been be a step forward in all three fields.
The other approach mentioned by Judy: Making enlarged negs (lithographic
film) from original negatives by direct positive method is not approprite
for me because I want my large negs to be developed by a staining (negative)
developer.
I have not given up though, updates (like the ones promised? by Judy are
welcome.
All the best to all of you,
Istvan
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