Contrast Index vs. Gamma - 70 year old Verichrome and Super XX Film

MattKing · Apr 20, 2016

I'm in the midst of an experiment here, and thought I'd ask for some input.

Two days ago I exposed a roll of film that had a develop before date of 1951, in a camera manufactured in or about 1936.

The film: more than 65 year old Kodak Verichrome (not Pan) in 616 size

The camera: an 80 year old or so Kodak Six - 16 folder.

I made a decision to meter the shots at an EI of 6. I'm trying to determine a developing time.

I intend to use HC-110 dil B.

My 1940 Kodak Reference Handbook recommends for Verichrome a time of 20 minutes in D-76, using 18C and intermittent agitation. Note however that this is for a target gamma of 0.9.

In that publication, the Sensitometric curve for the film indicates that for a target gamma of 0.6, the recommended time for Verichrome in D-76, using 18C and intermittent agitation, is 13 minutes.

Moving ahead to my 1970 issue of the Kodak Master Darkroom Dataguide, there is of course no listing there for Kodak Verichrome. There is a listing for Verichrome Pan, but the recommended development times for it in D-76 ( 8 minutes at 18C) are considerably different than either of the 1940 recommendations for Verichrome.

In more modern Kodak data sheets, the term "gamma" is replaced with "contrast index". And the recommended development times from those data sheets appear to be correlated to a target gamma of 0.6.

My plan is to develop the film in 18C HC-110 at a 1+24 dilution, using that as an equivalent to D-76.

I am thinking about developing the film for 13 minutes, with agitation for 5 seconds every 60 seconds.

This is dependent on two assumptions, which I'm asking about here:

1) the reference to "gamma" in Kodak's 1940 publication is functionally equivalent (for my current purposes) to the references to "contrast index" in later publications; and
2) the modern target contrast index of 0.6 is more appropriate for my use.

What are your thoughts about my assumptions?

I have already ruled out stand development. Do you have other suggestions?

Gerald C Koch · Apr 20, 2016

Contrast Index and Gamma differ slightly because of the way that each is determine from the Characteristic Curve. The new method of calculation was devised by Kodak but never caught on with any other film makers. The following article descirbes them in detail.

http://photographytraining.tpub.com/14208/css/14208_57.htm

MattKing · Apr 20, 2016

Thanks Gerald.

One relatively clear thing I take from your link is that the numbers don't equate - a gamma range of 0.65 to 0.90 is approximately the same as a contrast index range of 0.56 to 0.60.

So I should probably consider something longer than 13 minutes.

Arklatexian · Apr 20, 2016

MattKing said:
I'm in the midst of an experiment here, and thought I'd ask for some input.

Two days ago I exposed a roll of film that had a develop before date of 1951, in a camera manufactured in or about 1936.

The film: more than 65 year old Kodak Verichrome (not Pan) in 616 size

The camera: an 80 year old or so Kodak Six - 16 folder.

I made a decision to meter the shots at an EI of 6. I'm trying to determine a developing time.

I intend to use HC-110 dil B.

My 1940 Kodak Reference Handbook recommends for Verichrome a time of 20 minutes in D-76, using 18C and intermittent agitation. Note however that this is for a target gamma of 0.9.

In that publication, the Sensitometric curve for the film indicates that for a target gamma of 0.6, the recommended time for Verichrome in D-76, using 18C and intermittent agitation, is 13 minutes.

Moving ahead to my 1970 issue of the Kodak Master Darkroom Dataguide, there is of course no listing there for Kodak Verichrome. There is a listing for Verichrome Pan, but the recommended development times for it in D-76 ( 8 minutes at 18C) are considerably different than either of the 1940 recommendations for Verichrome.

In more modern Kodak data sheets, the term "gamma" is replaced with "contrast index". And the recommended development times from those data sheets appear to be correlated to a target gamma of 0.6.

My plan is to develop the film in 18C HC-110 at a 1+24 dilution, using that as an equivalent to D-76.

I am thinking about developing the film for 13 minutes, with agitation for 5 seconds every 60 seconds.

This is dependent on two assumptions, which I'm asking about here:

1) the reference to "gamma" in Kodak's 1940 publication is functionally equivalent (for my current purposes) to the references to "contrast index" in later publications; and
2) the modern target contrast index of 0.6 is more appropriate for my use.

What are your thoughts about my assumptions?

I have already ruled out stand development. Do you have other suggestions?

It might be a good time, at this point, to remind you that you made a point of saying that this is Verichrome, not Verichrome Pan. This means that you can develop by inspection under a red (preferably what we called a ruby bulb with the color fused into the bulb glass, not painted on, though painted on will work if there is no "white light showing). This means you will have the opportunity to develop by inspection and not be limited to developing by time and temperature as with "pan" films. As I have forgotten how to do this, some of the older "farts" may either remember how or have old instructions laying around. All I remember is that you pay attention to the film "base" side while see-sawing" the film through a tray of developer. I would use some active developer like dilute Dektol, then stop and then fixer.....It is important to use the "red" light, not the paper safelight. If it comes out as it should, you will have gotten a taste of how us Boy Scouts developed our film in the 1930/very early 40s period.......Good Luck and Regards!

Gerald C Koch · Apr 20, 2016

If you decide to develop by inspection make certain that you evaluate the progress by looking at the back of the film NOT the front. If you judge by the front your negatives will be very underdeveloped.

MattKing · Apr 20, 2016

Thanks for the suggestion.

There are two and one half reasons I have decided against development by inspection:

1) I've never done it before, and as I understand it, you are only likely to do this successfully if you already know how film developed this way should appear when it is "done";
2) This is likely to be a really curly roll of almost 70 year old roll film, not a nicely behaved, flat piece of sheet film. I'm counting on not having to handle the wet film in the dark; and
2.5) I have no idea if my red LED safelights are safe with Verichrome, and I don't have enough of the film for testing to make any sense.

But the suggestion was good....

Arvee · Apr 20, 2016

MattKing said:
Thanks for the suggestion.

There are two and one half reasons I have decided against development by inspection:

1) I've never done it before, and as I understand it, you are only likely to do this successfully if you already know how film developed this way should appear when it is "done";
2) This is likely to be a really curly roll of almost 70 year old roll film, not a nicely behaved, flat piece of sheet film. I'm counting on not having to handle the wet film in the dark; and
2.5) I have no idea if my red LED safelights are safe with Verichrome, and I don't have enough of the film for testing to make any sense.

But the suggestion was good....

If you're not going to develop by inspection and you think all frames were exposed and the roll completed, why not snip off 6" or so and try your best 1st shot? That way you get another go at it to adjust development with the minimal loss of a frame or two instead of blowing the entire roll if you guess wrong.

ic-racer · Apr 20, 2016

I'd be surprised if you got anything useable no matter how you processed it. Having said that, please surprise me if you get results and post them.

MattKing · Apr 24, 2016

ic-racer said:
I'd be surprised if you got anything useable no matter how you processed it. Having said that, please surprise me if you get results and post them.

So I ended up developing this today, and there are images there! The film is drying as we speak.

I used HC-110 one shot at a 1+24 dilution, and 65F/18C. I developed the film for 18 minutes. I agitated continuously for the first 30 seconds, and then for 10 seconds every two minutes thereafter.

I've been using HC-110 replenished for so long it was very strange to discard the developer after using it.

The film is extremely curly - loading my adapted reels was extremely difficult, and there are some damaged edges. There is lots of fog, but images are clearly there.

I don't have the ability to scan the full width of the film, but I'll either get a scannable contact print from it soon, or work up a kludge that will allow me to post something here sooner.

ic-racer · Apr 24, 2016

MattKing said:
So I ended up developing this today, and there are images there! The film is drying as we speak.

Are you able to measure base density? I have a little base density project going on some unprocessed HP5 that has been in continuous cold storage from about 1983 or so. When I get a few more datapoints I'm going to plot out density vs year or decade. Might give some useful predictive information.

MattKing · Apr 24, 2016

ic-racer said:
Are you able to measure base density?

I'll ask my friends if they can use their densitometer on the negatives for me.

Unless you will accept "mid-gray" as an answer!

Jim Noel · Apr 24, 2016

To summarize a lof this and add my points:
testing a safelight.
1. turn off all other lights and leave the red light on.
2. Use a CD or DVD and look at the reflection; if safe you will only see red on the disc.
to develop:
1. definitely develop by inspection. I developed my first 100 or so rolls of Verichrome beginning in 1937,all by inspection.
2. If you want to use HC 110 use Diution H - twice the water of 'B"
3. Use at least 6-8 ounces of developer in an 8x10 tray.
4. with your gloves on place the roll of film in the tray.
5. holding the roll gently by its ends, pull the film up and out of the tray until you are holding only the end in the tray, then let the film re-roll upon itself.
6. repeat this motion every 20-30 seconds.
7. look at the base side of the film. - when you see the highlights (the dark parts) with some clarity move the film to a water bath, the to the fixer.
8. Your time will belong because of the more dilute developer and the fact that those old orthochromatic films required longer development times than modern panchromatic ones.

MattKing · Apr 25, 2016

I had some success with scanning the negatives. Surprisingly they have dried relatively flat.

There is no sign of any of the edge printing - I guess if there was any, the almost 70 years that has elapsed since the edges were exposed has caused it to disappear into the fog.

The texture of the backing paper is almost impressed into the film.

I don't think the camera is leaking light.

I'm amazed at how much is there.

nosmok · Apr 27, 2016

Looks like ya done good. I haven't had too much luck with Verichrome 616, better luck with VC-Pan; I have 1 roll that's waiting on me finishing my bodged up 70mm holders to scan. Looks like you got the exposure all right. I do mine in Caffenol-C; I look at the rinse water and if I don't see enough discoloration I pour the developer back in for 5 minutes more. Now you've got me wanting to finish that holder!!

MattKing · Apr 28, 2016

I decided to try a further experiment. This time I used the same camera to expose another 616 roll of the same vintage - Develop before 1951. This one was a roll of Kodak Super XX.

The original ASA of the film was 100. Of course, that was before the ASA standard was changed, so the closest ISO comparison would now be 200.

Super XX was panchromatic, unlike Verichrome.

Based on my experiment with Verichrome, I decided to meter this roll at an EI of 25. I bracketed by exposing at that indicated exposure, and then exposing again with an additional two stops (or so) of light.

Exposures were taken on a nice sunny day, but some of them were in shade.

Loading the reel was again incredibly challenging. Of course, if I had been stored tightly wound around a spool for 70 years I might be curly too! In any event, one of the eight frames ripped completely, and there is at least some damage on the rest.

I elected to use my standard developer of HC-110 dilution E (replenished) rather than the much stronger dilution I used with the Verichrome film. I also worked at a more usual temperature of 69F/20.5C. I decided on a development time of 17 minutes with continuous agitation for the first 30 seconds and additional agitation for 10 seconds starting at 2 minutes and repeating every 2 minutes thereafter.

Interestingly enough, on this film I can read some edge printing - Kodak Safety Film - but no numbers. And the edge printing is so close to the edge it is almost like the film shrunk and the edge printing nearly fell off the edge.

Oh and the backing paper is an interesting dark green, with the numbers added in silver ink.

Here are scans of four of the seven surviving negatives:

MattKing · Apr 29, 2016

ic-racer said:
Are you able to measure base density? I have a little base density project going on some unprocessed HP5 that has been in continuous cold storage from about 1983 or so. When I get a few more datapoints I'm going to plot out density vs year or decade. Might give some useful predictive information.

Thanks to my friends, I have some data for you.

First, as a comparison, my friend measured base densities of two recently processed, current films.

FP-4 developed in D-76 1+2 was measured at 0.11.

TMY-2 developed in HC-110 dilution E (replenished) was measured at 0.16.

Moving on to the old films:

1951 Verichrome developed in HC-110 diluted at 1+24 was measured at 0.61

1951 Super XX developed in HC-110 dilution E (replenished) was measured at 0.59.

All measurements were taken in the approximate middle of the film, in the blank area between two adjacent frames.

Hope this is helpful.

Disconnekt · Sep 15, 2022

Sorry for reviving this thread, would the time you used for the Super-XX film be good for the 35mm version of Super-XX? Just got one off ebay that expired December 1955

MattKing · Sep 15, 2022

Disconnekt said:
Sorry for reviving this thread, would the time you used for the Super-XX film be good for the 35mm version of Super-XX? Just got one off ebay that expired December 1955

Tough to tell. Among a number of other differences, your 35mm film doesn't have backing paper, so the aging process may have proceeded in a very different manner.

Bill Burk · Sep 15, 2022

I would use the lowest ASA setting you have: 2, 3 or 4

9 minutes D-76 stock at 68-degrees F with a quarter tab of Kodak Anti-Fog (Benzotriazole), about “half” the recommended amount

See thread 'Should I get a really old roll of film?'
https://www.photrio.com/forum/threads/should-i-get-a-really-old-roll-of-film.178338/post-2326332

Romanko · Sep 16, 2022

Attached is the data sheet from Kodak Reference Handbook (1946):
The handbook is available online:

Kodak Reference Handbook : Eastman Kodak Corporation : Free Download, Borrow, and Streaming : Internet Archive

Some Kodak reference booklets about Lenses, Films, Filters, Papers, Formulas, Processing and Copying.

archive.org

I processed two rolls of Super-XX in 127 format from 50s-60s and they came out pretty well. I used Barry Thornton's Two-Bath developer for 4.5 min (bath A) and 4.5 min (bath B).

MattKing said:
35mm film doesn't have backing paper, so the aging process may have proceeded in a very different manner

In my experience exposed and unprocessed roll film keeps much better than 35 mm, but I only developed several rolls of 35 mm, most my "mystery" film is 127 and 120/620 types, occasionally 116/616.

You can expose a few frames from the roll and process them. John Finch from Pictorial Planet made a video on how to do this:
I have a Smena-8m camera that can use two cassettes which makes it even easier.

Good luck with your Super-XX!

Contrast Index vs. Gamma - 70 year old Verichrome and Super XX Film

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