Reverse development

[chrisgerrist]

I would like to have positive black and with 4x5" sheets. When I search on the internet I found some discussions about a positive development process for example Kodak Tmax 400 black and white film. Today I did a test with a 120 rol of film and the result: a clean film without any image.

Process I followed:
development 6 minutes
bleach 1 minute
fogging 30 seconds
development 1 minute
stop 1 minut
fix 10 minutes
clean 10 minutes.

Who can help me with the correct development process.

With kind regards,

Chris

[Erik Larsen]

http://www.apug.org/forums/forum37/8...l-options.html

This link is a good discussion of the process.
It is pretty simple to do.
Regards
Erik

[johnielvis]

don't know what chemicals you're using...or what speed you're shooting, but here's what works for me:

expose TMY at ei 100 to 200 say...nothing higher than 200

developer is D-19 kodak cut 1:1---FIRST DEVELOPER at 75 DEGREES F

develop this--10' (for the ei100)...longer dev for lighter images...any longer than 15' and you'll for sure be developing fog and lose dmax

the rest of the process is NOT critical with the temparature--

then water rinse...LOT of water rinse..make sure no developer remains and ph is neutral.


then BLEACH--I use dichromate an sulphuric acid...bleach for 2'...

then WASH the film again.....a bunch of times...lots of orange comes out

then CLEARING BATH--I use sodim sulfite or hypo clearing agent...say 1' max

then WASH AGAIN

now take out the film and expose it to light for like 2 minutes....

now...develop the film again (use the same developer from the first development is ok and less waste).....I develop for 5 minutes for the d-19

the slides are done, but there remains, particuilarly with tmax films, extra unexposed silver halide to get rid of---it looks yellowish...you can keep it OR

FIX for 10' in pure hypo

wash and photoflo and hang to dry.

too light? develop less or expose less

too dark--develop more (first develop) or expose more.

only chemicals you need are potassium dichromate/sulphuric acid bleach
sodium sulfite
developer--very strong--like d-19 or a strong paper developer

[Donald Qualls]

Here's a link to my reversal process:

http://silent1.home.netcom.com/Photo...ml#BW_Reversal

Most important error in yours, I think (assuming you didn't use Farmer's Reducer or C-41 bleach), is failure to develop the second developer to completion; contrast/speed are controlled by the first developer and to a lesser extent by either the amount of fixer in the first developer or by a "density control" step (with dilute fixer, by inspection) between bleach and second developer (done in the light, this also provides the fogging). I haven't done my process with large format film, but on 35 mm it produced slides with 400TX with a real speed of ISO 1000, and that had the grain I'd usually expect from an ISO 100 or slower conventional grain film; with another developer as first developer, I could probably increase that effective speed to ISO 5000 or 6400 (and still keep the fine grain in the final slide).

Do note that the process will be different with a T-grain or Delta film, as those films fix more slowly and thus will require either a higher fixer concentration or longer density control step.