# I Have A Question About X-Ray Film For Silver



## scrapparts (Sep 20, 2017)

Hello members,

When I (or you) look at x-ray film with, light behind it, do the parts that you're looking at contain silver or does the whole x-ray film have silver on it? 

Example: If I looked at an x-ray of a foot, would just the foot portion of it contain the silver?

Thanks

scrapparts


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## g_axelsson (Sep 20, 2017)

Silver is the black ink. Anywhere the film is clear is missing the silver.
Undeveloped film has all the silver still there.

Göran


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## scrapparts (Sep 20, 2017)

g_axelsson said:


> Silver is the black ink. Anywhere the film is clear is missing the silver.
> Undeveloped film has all the silver still there.
> 
> Göran


Thanks for the reply. Now I know.

scrapparts


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## jimdoc (Sep 21, 2017)

You have to make sure it is silver film, and not the newer stuff.


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## goldsilverpro (Sep 21, 2017)

It depends. If the film is of the "wet" type, that which is developed by wet chemistry, the black areas contain all of the silver. If it is of the "dry" type, that which is developed by heat, both the clear and black areas contain silver, evenly. For the "dry" type, undeveloped and developed film contain the same amount of silver, since none is lost during development.


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## g_axelsson (Sep 21, 2017)

You learn something new every day. Thanks!

Göran


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## scrapparts (Sep 21, 2017)

Thanks for all the added info. 

One more question though. How can you tell the new types of film vs the older types?

scrapparts


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## jimdoc (Sep 21, 2017)

http://goldrefiningforum.com/phpBB3/viewtopic.php?f=50&t=213&p=1673&hilit=x+ray+film+types#p1673

http://goldrefiningforum.com/phpBB3/search.php?keywords=x-ray+film+types


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## goldsilverpro (Sep 22, 2017)

scrapparts said:


> Thanks for all the added info.
> 
> One more question though. How can you tell the new types of film vs the older types?
> 
> scrapparts



Hold a cigarette lighter flame briefly under a clear area of the developed film. The "wet" film will be unaffected and, with the "dry" film, a black spot will appear. Don't hold the flame close enough or long enough to burn the film - this takes a little experience. It only takes about one second or so, with the tip of the flame about 1/2", or so, away from the film. 

Another testing method is to put a small piece of the black area into a small amount of liquid laundry bleach (or 10% v/v HCl). The "wet" type will strip, but the "dry" type will be unaffected (will remain black). This method was given by our old forum friend, Juan Manuel Acros Frank. I haven't tried it as a test method but, from my experience with bleach on "wet" film, I'm sure it works.

Modern catscans are usually the "dry" type but regular x-rays can also be "dry." 

To the eye, developed "wet" and "dry" film look identical. Whereas "wet" film is easy to process, "dry" film is almost impossible. The silver behenate compound on the "dry" film is unaffected by just about any practical chemical I know of. I have been able to put the silver into solution with boiling 25% nitric acid, but that is not practical at all. Unfortunately, when you get a batch of developed medical x-ray film, you will find a mixture of "wet" and "dry" film that you cannot readily sort and separate. This has made the processing of medical x-ray film a difficult thing to do.

It is interesting to note that UNdeveloped "dry" film is almost fully transparent. It appears as a clear blue (usually) plastic with a very slight haze to it - you can definitely see through it. It looks like "wet" film that has been totally stripped. It doesn't turn black and opaque until heat is applied to it.


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## rickbb (Sep 22, 2017)

goldsilverpro said:


> [ Unfortunately, when you get a batch of developed medical x-ray film, you will find a mixture of "wet" and "dry" film that you cannot readily sort and separate. This has made the processing of medical x-ray film a difficult thing to do.



Not to mention that it's all going digital and processing x-ray film of any kind will disappear completely soon. 

My local source just converted and before I could make an offer on his old files someone came in and offered him 5 cents apiece for them. I don't know how they plan to make money at that, that's way above the dollar a pound average, they must have a lean running operation and low margins.


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## rickbb (Sep 22, 2017)

And yes, bleach will instantly strip the emulsion off any "wet" developed film, x-ray, litho, photo. When I was in the printing business back in the pre-computer days we used bleach to remove our mistakes. It was much faster and cheaper than starting over on a 36 x 56 inch sheet of film.


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## goldsilverpro (Sep 22, 2017)

Due to "dry" film and digital x-rays, the processing of scrap x-ray and litho film is nearly a thing of the past, except in some 3rd world countries. About the only exception are Industrial X-Rays, which are used for such things as the inspection of pipeline or nuclear power plant welds. I haven't really kept up with this industry in the last few years, but I haven't heard of it going digital yet, nor have I heard of the use of "dry" Industrial x-ray film. Industrial x-ray film has always had the highest silver content of any film - about triple that of medical "wet" x-ray film and double the best litho film.

Industrial x-rays are used for many different things. I once heard a story about a huge turkey processing plant, in Kansas, I think, that somehow had a broken off knife blade buried in one of the 250,000 processed and packaged turkeys that were ready for shipment. With most stories, the numbers always seem to get bigger the more the story is told, but that's honestly the number I was given. To avoid getting sued, they hired an Industrial x-ray company to come in and shoot x-rays until they found the offending turkey. I have no idea how many turkeys they "shot" before they found it. I was told that they did find it.


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