Help x-ray film woes
I am using Fuji single emulsion mammo x-ray film for enlarged negatives. I have done this successfully with making an interpositive first etc and using paper developer. I just tried to use an actual print as an interpositive as I have heard of others doing this. Everthing comes out as a perfect positive! I am developing in D-55 4:1 and exposing in a contact print frame under a 300w bulb at about 30in. its totally weird! I have tried exyending exposure and decreasing to ridiculously low and its always a positive! Could it be my developer? I don't know.
You are contact printing a positive paper print onto what?
I wonder if it is some odd optical effect due to two negs being close together.... isn't the extra film coated on both sides? If so then I guess one emulsion will be sharp and the other not... and then... I don't know. Try printing it!
Is it possible that you are getting the effect of solarizing? 300w is pretty bright.
That's also the only thing I could think of. One method of producing positives from positives is to overexpose to the point where the silver halide grains "do a 180°". That's oversimplified for such a complex reaction, but I believe that's kinda how it works. There is a discussion on this topic somewhere...
Originally Posted by Rich Ullsmith
If you've found a way to get a direct positive from mammography film, that might be a very interesting technique to exploit!
Thanks to all for the comments. It seems I should patent my process as I have found a way to create a direct positive from a positive print! Yes it is due to HORRIBLE overexposure, I had stupidly assume that since I was trying to penetrate fiber base paper that I would need mega-light....wrong! I ended using my D@ with cold lite stopped down to F32! at about 80cm for 4 sec, when using the 300w bulb I was giving 40sec! What was i thinking? anyway all is well that ends well. BTW mammo x-ray film is single emulsion very fast(blue/green sensitive) and has great sharpness abiet a blue base that doesn't seem to affect anything. I develope it in Ilford PQ paper developer for about 2 min. It does require at least a 1 minute presoak as the heavy anti-halation coating interferes with developement. I get this stuff for free from some of my customers as everyone is switching to digital imaging.
Originally Posted by holmburgers
I've gotta try it! I'm using Agfa mammography film and I agree that it's a good film. I also had trouble with some mottled development and maybe the anti-halation dye was my trouble...
I haven't fooled around with it much more than the 2 instances, though I got a nice enlarged negative by enlarging a b&w positive onto the film and developing it in HC-110, dil B.