Enlarged Negatives for Pt/Pd

[cchisena]

I have been experimenting with BPFB-18 film in 12X16 size enlarging 6X7 negatives to 11X14 using a 16X20 Unicolor print drum with TMax-100 reversal chemistry. I started with a Pyro-Cat negative and got surprisingly high contrast( Range 2.25 to .32 ) The enlarged negative printed nicely. My understanding is that stained negatives are difficult to scan.At this time I'm not ready, nor do I have the equipment to do digital negatives. I also have lots of medium format negatives souped in PMK, Rollo Pyro, and Pyro-Cat.The BPFB-18 is expensive and so is the reversal chemistry,but I'm saving the interpositives and most of the tests for exposure,also less dust.The TMax chemistry works fine with no light reversal and I'm concerned that they could cancel it at any time. I was hoping somene might suggest a similar formula that I could mix or perhaps modify the Formulary Kit.Also, is it possible to use Pyro-Cat in the redevelopment stage?Any advice would be greatly appreciated.Chip

 

[Don Dudenbostel]

What is BPFB-18 film and who carries it?

 

[cchisena]

It is a blue sensitive ortho enlarging film sold by Bostick and Sullivan.Chip

 

[snallan]

Have you seen this article - Less is More - Negatives by Reversal over at Unblinking Eye? It will help with alternative recipes, and strategy to control contrast in the copy negative, though it does use light reversal rather than chemical. You might be able to get round this by adding a fogging agent, such as stannous chloride to your second developer.

 

[Don Dudenbostel]

No problem with light reversal. I ran thousands of sheets and rolls of E3 chrome in the 60's and early 70's.

 

[kwmullet]

Anyone got a pointer to a recipe for a bleach to use in this kind of reversal process that doesn't use Sulphuric Acid?

 

[snallan]

Anyone got a pointer to a recipe for a bleach to use in this kind of reversal process that doesn't use Sulphuric Acid?

I use Sodium Hydrogen Sulphate (Sodium Bisulphate) in place of the sulphuric acid, as a powder it is easily handled. Use it at around 5g in place of each millilitre of concentrated acid.

I believe it is available from pool and spa suppliers as a pH modifier, generally known as a pH reducer, or dry acid.

 

[Lukas Werth]

Have you seen this article - Less is More - Negatives by Reversal over at Unblinking Eye?

I have been using this procedure which was, as far as I know, devised originally by Liam Lawless, albeit in a considerably altered form, using Freestyle's lith films, and I think it is capable to give absolutely first-rate results. I am in the process of shifting my residence, and therefore have little time to spare, but once I am able to breathe again, I am thinking of posting my version of this procedure on my website.
Here a few remarks for those interested: 1) I use only one dish, and change baths by pouring fluids in and out. This dish has to have a flat and clean surface, no grooves or something, or for some reasons traces of these will be in the negative. 2) Rather than using a paper developer, I use a Rodinal formulation, diluted 1: 25, time 8- 9 minutes, first minute continuous movement, then once a minute. When sing a paper developer, highlight contrast is a problem; Rodinal gives a much longer and more even density range. 3) after stopping, I give a short wash with a little distilled water which I also use to make up the bleach bath. 4) no sodium sulfite, no hardener, just wash until the dichromate is ll gone, then redevelop.

When I fogg before development with a 15watt bulb from a hight of 2 1/2 meters (I live in a flat with high ceilings) for 2,5 seconds, from my already contrasty negatives I get a density range well suited to pl/pd.