X Ray positives?

[Petzval Paul]

Hi everyone,

I'm trying my hand at making Resinotypes (nearly obscure prices similar to Oil printing, bromoils, etc) and I need to print from a positive. I currently use x ray film exclusively to make my 8x10 negatives and I've been trying to contact print them to create positives with little luck. I had been considering ordering up some Arista Ortho Lith film, which I useda bit back in the early 2000's. However, I've heard that there is something called x ray *duplicating* film which has spiked my curiosity. Does anyone have any experience with it? I'm wondering if it would work better for my purpose, or maybe to use in camera? It's that a crazy idea? Thanks in advance!

[pound]

you can do reversal processing on xray film to turn it into a positive.


you can mixed yr own chemicals or get the B&w reversal processing kit for foma, adox or rollei . You may have to test for optinum exposure although usually you have to overexposure by 1 stop to get a good density positive.

[Tin Can]

I have enlarged on Huge xray film from a negative making a Positive

Way easier

[Kiwi7475]

I have enlarged on Huge xray film from a negative making a Positive

Way easier

I’ve been meaning to try this, and was wondering how do you determine the required exposure to the X-ray film without having to try and iterate multiple times? Is there an incident EV or something like that that one could measure with an incident meter for a given exposure time?

[Tin Can]

I’ve been meaning to try this, and was wondering how do you determine the required exposure to the X-ray film without having to try and iterate multiple times? Is there an incident EV or something like that that one could measure with an incident meter for a given exposure time?

Test strips

I enlarged from 5x7 onto 4 sheets 14x17 edge to edge testing with 5~5x7 sheets at critical points

No meter needed and I have a high end Sekonic

[Kiwi7475]

Test strips

I enlarged from 5x7 onto 4 sheets 14x17 edge to edge testing with 5~5x7 sheets at critical points

No meter needed and I have a high end Sekonic

Right, I just wanted to get close enough to start with.

I guess I can guesstimate it from the fact that paper, say Ilford MG RC, is somewhere in the ISO 3-6, so if x-ray is ~80, I can try opening the aperture 3 stops and doing exposures on 1 sheet by covering small portions at a time (like you do for paper strips, lol), covering several 1/2 stop steps.

I don’t want to get into many seconds bc then reciprocity kicks in, and it’s awful for x-ray, so one has to find the right aperture/time combo that is both accurate and repeatable.

Once I get it this way I can just measure the EV with a meter and that way I know what I need to achieve for any enlargement size.

[Paul Cunningham]

There is indeed duplicating film that produces a positive when processed normally. I have a box of 8x10 dental duplicating film that I have only tested in the darkroom, but I can confirm that it creates positives directly without reversal processing.

[koraks]

I don’t want to get into many seconds bc then reciprocity kicks in, and it’s awful for x-ray, so one has to find the right aperture/time combo that is both accurate and repeatable.

.

You won't have to; exposures will be just a few seconds at a small aperture. Reciprocity is not going to be an issue. Just give it a try; expose say a 4x5" sheet in strips of consecutive stops (1 second, 2, 4, 8 etc), develop and evaluate.
The main challenge is not so much exposure itself but getting the right contrast for your printing process. So you'll have to work out the right ratio between exposure and development for a particular image. Its labour intensive but that's what alt process printing is for!

[Tin Can]

Please name it

There is indeed duplicating film that produces a positive when processed normally. I have a box of 8x10 dental duplicating film that I have only tested in the darkroom, but I can confirm that it creates positives directly without reversal processing.

[Paul Cunningham]