Silver content of BW film in g/cm2

hoojammyflip · Sep 8, 2011

I've been searching the web for some data on silver content of film to see whether these price rises in film are really justified by the increase in the silver price.

Please can someone contribute a figure for the mass of silver bromide in film in g/cm2.

I have been using a figure of 5mg/cm2 which would currently lead to USD 1.7 per roll with silver trading at USD 42/oz. This would potentially justify price rises in film, but elsewhere on the Apug I saw figures of 1g/m2 which would be 0.1mg/cm2....this would mean the price rises in film could not be justified by silver prices...

Ian Grant · Sep 8, 2011

I had fairly accurate figures for silver content of films at one time they are archived on an old hard drive somewhere, the figure's usually given in grams per square metre.

For B&W films you are looking at 3-5 g/m2 so it looks like you're figure is out by a factor of 10. If a film contained $1.7 of silver a roll (your figure) then that would add more than $6.8 to the cost of each roll after distributor & retailer mark-ups, transport costs etc.

Back in the 1990's I ran a lab testing precious metals and we routinely tested films for silver content and there is some variation X-ray films have the highest silver content, films like Tmax 100 closer to the minimym figure. Colour papers can be closer to 1g/m2.

Ian

matt nalley · Sep 8, 2011

I've done some research on this recently to estimate how much elemental silver I could potentially recover from developed negatives (just for fun). A very rough estimate is about 0.01g or 10mg per frame (35mm) which is roughly 0.25g or 1/3g for a 24-exposure or 36-exposure roll, respectively.

Ian's figures are probably more accurate, but I think my calculations are much closer to his numbers than yours. I was just trying to come up with a number that is easy to work with in terms of frames rather than square meters because I only have a few dozen rolls compared to the hundreds that labs handle, so I'm sure I fudged a little to end up at that nice round 10mg per frame number.

georgegrosu · Sep 8, 2011

Until 1990, we do review the content of silver in film.
What comes to mind are: - Fuji color negative 35 mm ~ 170 g/1000 m;
- Negative b&w Azo 35 mm ~ 130 g/1000 m;
- color positive Orwo 35 mm ~ 90 g/1000 m;
- color positive AzoColor 35 mm ~ 75 g/1000 m;
- Positive b&w 35 mm ~ 100 g/1000 m.

After 1992 - 1994 the silver content in films of all low and not later tests were done because of the small amount of film processed.
I remember that the color positive came to 65 g/1000 m.
1000 m of 35 mm film has an area of ~ 30 square meters.
300 meters of film weighing about 2 kg.
George

paul ron · Sep 8, 2011

I've asked this same question a few years ago n all I got were theretical answers based on densities n whatnot. I see you've actually quantified the amts, thanks.

What I'd like to know is if the amount of actual silver content has gone down over the years say comparing TriX of 1970s to present day TriX coatings?

.

Photo Engineer · Sep 8, 2011

At Kodak, we used an odd measurement system which used mg/square foot. I will give the values in those terms and you can convert.

Common B&W films fall in the range of 150 - 300 mg / ft sq, color about 300 mg / ft. sq or about 100 in each layer. Color paper is about 50 - 100 mg / ft sq. Older X ray film was up to 2 g / ft sq, but has been lowered by a great deal in the last 10 years. IDK the current values.

The price of film also is based on labor and on plant costs such as taxes and utilities. As production decreases, costs go up and the customers have to bear the cost. So, an idle plant still costs money but brings in no revenue. Also, not just any old Silver can be used for film. It must be ultra pure, and is not jewelry or coin grade. I have been present at meetings where our combined data on emulsions caused us to reject a huge batch of Silver due to a trace impurity that caused bad keeping and fog in high speed films. So, the approval of each new batch of Silver becomes time consuming and difficult as the companies hunt for lowest cost, high quality Silver. In the film business, you cannot buy cheap silver, just the least expensive at the best quality.

There is a long thread on this here on APUG.

PE

hoojammyflip · Sep 8, 2011

Ian Grant said:
For B&W films you are looking at 3-5 g/m2 so it looks like you're figure is out by a factor of 10....

X-ray films have the highest silver content, films like Tmax 100 closer to the minimym figure. Colour papers can be closer to 1g/m2.

Ian

Thanks for this, exactly what I was looking for. Indeed, my data was ripped from a medical physics paper discussing Xray stuff.

So this means the raw element, Ag, in the film comes to the value of about USD 0.2, taking a silver price of USD 42 and mass of pure silver of 0.12g per 135 roll.

Granted, silver used in photographic film is purer grade than that referenced by futures trading on COMEX, but it will be at a relatively fixed spread to it, not a percentage (for example, crude oil into heating oil costs USD 10, whether crude trades at USD 70 or USD 140). Otherwise refiners go bust when commodity prices fall.

So it would appear that my 25% year on year film price increases are likely due to something other than the cost of silver.

Which begs the question why Fuji would have made this statement in this thread:
(there was a url link here which no longer exists)

Ian Grant · Sep 8, 2011

The 300mg per Sq ft figure is cclose to 3 g/m2 some films are lower others much higher.

What's being forgotton is that the nominal $0.2 cost of silver per is high compared to the manufacturers price per film at the factory gate, there's profits and often 2 additional mark-ups to be added to reach the final retail price. Energy costs are a huge factor in film & paper manufacture as well as the rising costs of environmental compliance.

Ian

Jerevan · Sep 8, 2011

Not to mention the fact that the demand is going downwards, which means higher prices in the long run if you want to keep profitable.

EDIT: I saw now that PE already said this.

Ian Grant · Sep 8, 2011

Well Ilford have indicated that film sales are rising but then Ilford along with Foma & EFKE are is of the few companies left making a full range of B&W products.

Ian

paul ron · Sep 8, 2011

Thanks so much for this valuable information.

Does the amount of silver make a differnce in the image quality of the negative or is it just chemically overkill at some point, perhaps relative more to the thickness n consistancy of the emulsion?

Is there a way to know comparatively how much silver is in the different brands of films out there today?.. I never see this information listed anywhere.

.

Photo Engineer · Sep 8, 2011

The higher the Silver, the higher the speed, contrast and the lower the grain. Sharpness goes down as Silver goes up. In design work you have to find a balance between Silver, sharpness, grain and contrast as well as a whole host of other factors.

PE

paul ron · Sep 8, 2011

I have to say the quality of the T-Grain films are amazing, I love em. Film has gotten so good over the years but papers are really suffering badly. Once upon a time we had such beautiful papers to work with like my all time favorite AGFA Record Rapid. What has happened there?

Ian Grant · Sep 9, 2011

Record Rapid changed when Agfa removed the cadmium in the late 1980's, while the new version was good it just wasn't anywhere near as flexible. Later Agfa replaced it with MCC which to be fair was a good VC rplacement fot the last RR.

Fomatone MG Classic is a good replacement for RR, Forte Polywarmtone was even better but that's no more, I have a hundred or more sheets left

Ian

pgomena · Sep 9, 2011

Don't overlook the fact that silver content of color films is for unprocessed film. Both E-6 and C-41 processes remove all the silver in the bleach and fix steps.

Peter Gomena

Photo Engineer · Sep 9, 2011

Michael;

Virtually anything you do to an old style grain (K grain - for KLUNKER), can be done to a T-Grain but things don't go the other way in many cases. IDK right now as things have changed a lot in emulsion chemistry as has the silver content. I do know that Bill Troop and I have hand long discussions on this and several related topics and I think that statement could be enlarged upon and clarified if the book were to come out in a 2nd edition. Unfortunately, that will not come to pass.

PE

Ian Grant · Sep 9, 2011

Turning things upside down many of the advances made with T grain and non Kodak equivalents in terms of emulsion technology have been filterering through to older emulsions Tri-X, FP4 + and HP5+ etc.

Ian

Photo Engineer · Sep 9, 2011

Well, there are actually many many basic "upgrades" in emulsion technology over the original generations:

1. Single run, active gelatin either boiled or non boiled used up until about 1920 and is still used in some old product types.

2. Single run with ammonia (SRAD) - this is my ISO 40 emulsion posted here. It is a variant on a formula published by Baker in the 40s. He used active gelatin but I use inert PA gelatin and ISO wash.

3. Double run monodispers including T-grains, cubes (in Ektar) and octahetra.

4. Core shell grains of selected crystal habit. Many EK patents on this.

Then there is the chemical sensitization or finish and the spectral sensitization.

1. Plain dyes such as chorophyll and erythrosine (food dyes can work but poorly and require a different method for incorporation)

2. Inert gelatin + Allyl Thiourea, then Ammonium Thiocyanate then gold was added then they changed to Hypo and Hypo + gold. Often they added Rhodium Salts.

3. vAg control, Gold + Hypo + thioethers, dye layering and Osmium salts of sensitizing dyes (2 electron sensitization).

Then there is the coating technology such as blended emulsions for long latitude and curve shape control, the use of dyes for sharpness and speed control and etc. One of the first films with 2 emulsion layers, I believe, was by Perutz. Their film had 2 layers with a fast and slow emulsion. Overcoats to prevent scuff marks and back coats to give the film antihalation and antistatic properties. Agents were added to prevent curl and piping and the new hardeners introduced the modern era of films and processes.

So, there is a rough outline of the sequence of events on each divide of the emulsion making prepping and coating. Very short layman's outline of a complex situation. Lots is left out. But these things can be used on any emulsion type. Silver levels dropped throughout this period. Early on, many grains were "dead" or "inert" and did not develop so "silver rich" was a technology used to overcome a deficiency. Today it is used as a marketing point and having a "silver rich" film is supposed to be something special, but as technology moved forward, grains became more efficient at light capture and at development. So, silver levels came down.

PE

Photo Engineer · Sep 9, 2011

For those interested, look at the patents here: (there was a url link here which no longer exists)

PE

Monito · Sep 9, 2011

Michael R 1974 said:
Ilford calls their Delta films "core shell" technology.

Do they? I wasn't aware of that (no surprise). However, it seems oxymoronic, like "jumbo shrimp", since core and shell are antonyms. The shell surrounds the core. The core is contained by the shell.

Do they simply mean to say that their Delta films are core technology, meaning "key" or "essential" to the well-being of the company?

Photo Engineer · Sep 9, 2011

There are several types of "core shell" emulsions. The "graded iodide" has Iodide ion from the core to the surface, the "core shell" has an abrupt discontinuity in the Iodide from the core to the shell.

Delta crystals are more or less triangular in shape whereas the Kodak T-grains are hexagonal in shape.

Do you really want to go down this road guys? It is rocky, many branched and very technical!

PE

Monito · Sep 9, 2011

Photo Engineer said:
There are several types of "core shell" emulsions. The "graded iodide" has Iodide ion from the core to the surface, the "core shell" has an abrupt discontinuity in the Iodide from the core to the shell.

Delta crystals are more or less triangular in shape whereas the Kodak T-grains are hexagonal in shape.

Do you really want to go down this road guys? It is rocky, many branched and very technical!

Ah, very good! So it is a technical term. However, if I were the technical writer, I would call it "core and shell" technology or something like "sheathed cores" technology or "layered crystal". But then again I don't understand it well enough to advise, since the concept is new to me now.

I don't want to put you to any trouble at all going down one road or another. I will say that I read your posts with great interest when I find them and I know I'm not the only one.

Michael R 1974 said:
No they refer to "core shell" being the way they grow the crystals. I've seen several references to it but here's one in the bullet points describing Delta 100.

http://www.ilfordphoto.com/products/product.asp?n=8&t=Consumer+&+Professional+Films

Thanks for the link. I see they actually call it "core-shell crystal technology", which clarifies and specifies it more for me, using the hyphen and "crystal". Interesting.

Photo Engineer · Sep 9, 2011

Come to the workshop at GEH in Rochester in October then! Still a space left I hear.

PE

Hexavalent · Sep 9, 2011

Photo Engineer said:
..

Delta crystals are more or less triangular in shape whereas the Kodak T-grains are hexagonal in shape.

Do you really want to go down this road guys? It is rocky, many branched and very technical!

PE

Worried the conversation might go epitaxial?

Photo Engineer · Sep 9, 2011

I would turn this over to my buddy Joe Maskasky (patent hint). But, be careful, he and his wife have a pet snake (a large BOA )

PE

Silver content of BW film in g/cm2

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