Yes, the film base is blue... even before you develop it.
First of all, thanks to all who have contributed to this thread. Your experiences have created a de-facto manual for working with x-ray film. I recently decided to try it because of some interesting potential qualities I'll mention in a few lines. Your collective wisdom and willingness to share have provided a sort of "kick start" into working with x-ray film.
Now for my hair-brained idea. X-ray film has the image exposed on two layers of emulsion -- the side facing the lens being the primary image and the so-called back side being the secondary image. It occurred to me that the secondary image would be a bit fuzzy due to the image passing through the primary emulsion and the base material. This is really an unsharp secondary image (hopefully the lights are going on and you know where I'm going with this).
It may be possible to relatively easily create a built in unsharp mask for the primary image.
The trick (I think) will be to reduce (possibly proportionally) the secondary image.
The result (again, I think) will be improved contrast in the shadows and better acutance overall.
There have been several suggestions for removing the secondary emulsion by mounting the negative on a glass plate -- great idea. I'm now working on a reducing process that is controllable using that setup. For calibration, I'm shooting a white wall with a 4x5 Stouffer Step Tablet sandwiched on a sheet of Fuji Green X-ray film using an older wood film holder. The older film holder's internal guides has more slop so I can insert the two sheets of film together.
Using a controlled exposure, I can measure the developed and reduced film density on my old densitometer.
I think I have the process down -- I'm working on the reducing chemistry now. I need something that I can control the emulsion reduction -- Clorox Bleach is not a good idea -- It wasn't consistent enough except in strong working solutions and then it seemed to only consitently strip everything off.. I also splattered some on my shirt and pants -- now the wife is involved ;-(
I'm ordering Farmer's Reducer to see if that will give me better control over reducing the unsharp mask denesity -- something like maybe one half stop per minute.
I too have thought of ways to exploit the double sided image -- I've even tried to develop them separately. For me, the second image works best as a retouching mask. I've played with pencils, dyes, abrasives, knives, and even thickened ferricyanide bleach. There's a lot of potential there, but it takes practice.
Bill, thanks for the post.
I also bought the Fuji Green XRay film and was surprised at the blue base. So I admit to quickly trying to ballpark the exposure development and exposed at 100 and developed in HC-110 Dil B for 6 minutes then another shot for 3 minutes. Both are overly dense to my eyes but I haven't tried to bleach the one emulsion off, yet. The 3 minute neg is closer but I will try Dil H next time. I do have some scratches but I hope only on the bottom side.
Any suggestions as to dev times for Multigrade IV type contact printing appreciated.
I'm doing exclusively MG IV contact prints and I'm getting great results with Rodinal and stripping one side.
Cool...how long do you process in Rodinal and what do you expose at? And you are talking the Fuji Super HR-U? Thanks...
The unsharp masks that I make with "regular" film are pretty much the same as what should result from the X-ray film. I pin register a sheet of film - emulsion side to the back side of my original negative. That separates the two emulsions by only the thickness of the negative base. Putting more distance between does work for some pictures but you run the risk of causing an halo effect between high and low density areas in the photo and the image looks a bit artificial or outright strange. The mask doesn't look fuzzy to the eye ... Just much less dense. That's why I think the X-ray film will provide a subtitle crispness and a bit more shadow definition if I can control the density of the secondary image effectively... Time and experimentation will tell...
Thanks to all for your comments.
Enjoyed the blog, Bryan. Watch out for the alligators.