Help x-ray film woes

[ronlamarsh]

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.

 

[ic-racer]

You are contact printing a positive paper print onto what?

 

[keithwms]

Curious. Show!

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!

Interesting.

 

[Rich Ullsmith]

Is it possible that you are getting the effect of solarizing? 300w is pretty bright.

 

[holmburgers]

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...

If you've found a way to get a direct positive from mammography film, that might be a very interesting technique to exploit!

 

[ronlamarsh]

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...

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.

 

[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.

cheers!