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A New Method for Processing X-Ray Film

Anybody shooting large format film today knows that film is extraordinarily expensive. A sheet of 8x10" black & white film will run anywhere from $3 to $10. Those interested in ultra large format photography have come up with various ways of shooting on a budget: paper negatives, lith film, and X-ray film. X-ray film costs anywhere from $.50 to $2/8x10" sheet.

When you first think of X-ray film, you might imagine a film capable of seeing through surfaces. But get your mind out of the gutter! For the conventional photographer, X-ray film has some quirks. But if anything those quirks limit what the film sees, not expands.

X-ray films typically are orthochromatic. Much like films in the really olden days, they are not sensitive to the red spectrum. For your photography, that means a really red rose will look blackish. For portraiture, that means that freckles and zits will look darker than they do, so keep that in mind.

A big plus to orthochromatic films is that they can be handled and developed under red lights. So you can develop by inspection - actually watching the latent image materialize much like when you print conventionally.

Another quirk to X-ray film that presents the biggest challenge to conventional photography is that most films are coated on both sides! What does that mean to you, the budget large format photographer? Several things....

First off do you know what turns your prewash to blue, green, or black? When you pour clear tap water in to your film drum and it comes out colored, that is a dye adhered to the back of conventional films called an anti-halation layer. That prevents light that hits the film from bouncing around off the back of the film layer causing blooming highlights. If conventional film has an anti-halation layer, then you could call x-ray film's secondary layer a "pro-halation" layer. Instead of discouraging those hightlight blooms, x-ray film encourages that effect. Never fear, it can add unique feature if employed correctly.

Another related effect is that photos are going to appear less sharp. There are two identical images with a several micron thick piece of plastic separating them. So in addition to those blooming highlights, there will be a slight overall glow to any image.

But most importantly, the double sided emulsion makes processing difficult. Processing in a conventional drum blocks the chemistry from completely penetrating the back emulsion, which with normal film would just be the plastic backing. That effectively ruins your image, since the back emulsion is very unevenly processed. Some photographers deal with this problem by scratching off the back emulsion.

Other photographers have dealt with this by careful tray processing or other techniques. I've heard of people using ziplock bags as an example. But I've come up with what I think is an easier solution. I just lined the conventional 8x10" tray with plastic cling wrap. It seems to have minimized scratching problems and is very easy and cheap to apply.

Give it a try!

(sample photos to follow)


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