Film-Tech Forum ARCHIVE: Can modern mylar film replicate "nitrate glow"?

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Posted by Patrick J. McCart (Member # 1043) on 11-04-2001, 09:32 PM:

If you were to duplicate a nitrate negative to modern mylar film, would the picture retain "nitrate glow?"

I've seen a few DVD's with excellent nitrate film images, but I wonder if they went through the dangerous task of putting nitrate through a telecine or just used a mylar print from the negative.

Posted by John Anastasio (Member # 607) on 11-05-2001, 05:03 AM:

The film base itself is just a clear substrate upon which to deposit the emulsion, so there's no real reason for a different "look" to nitrate except that they used a lot more silver back then. The film itself shouldn't affect the picture. If you think about it, those old glass plates used in photography had a look to them that was even better, but it was because they had really thick emulsions on them...leading to a much richer look and wide tonal range with excellent grain structure. I'm sure John Pytlak will have some sage words on the subject. I just don't see why if they coated mylar with the same soup with which they coated nitrate stock, it wouldn't look pretty much the same.

Posted by Leo Enticknap (Member # 534) on 11-05-2001, 06:20 AM:

On the 'if you were to duplicate a nitrate negative' point, we also have to bear in mind that other factors beside the relative silver content of the emulsions may have degraded the image before it is copied, e.g. shrinkage, decomposition and physical damage such as scratching. A lot of the copying techniques used to offset these problems, most notably wet-gate printing, will produce a dupe that is not as sharp or contrasty as if it had been struck on a continuous motion contact printer.

Actually I wouldn't have thought that putting a nitrate element through a flying spot telecine would be that dangerous (from a fire risk point of view) just as long as any conductive surfaces in the film path were properly earthed, because the amount of heat generated by the lamp would be negligable. But from an archival preservation point of view this would be an absolute no-no unless the nitrate element was designated as 'surplus', i.e. another similar element is already preserved but in a better condition.

Posted by Jerry Chase (Member # 660) on 11-05-2001, 09:39 AM:

"Clear" is not always equal. Depending on the angle of incidence, there can be internal reflections that vary between bases. Required coatings could add other optical effects. Suggesting that "The film base itself is just a clear substrate" is oversimplification. Water, vodka, and hydrochloric acid are all clear liquids. Each has very different properties.

Grain structure and range is better in modern films. Part of what you might be noticing as a difference in nitrate is a shift in the sensitivity to blues and reds from ortho to panchromatic film. I've never seen the true "nitrate look" to pass even through one generation of copying to a different media. However, I'll be pleasantly surprised if someone proves this wrong.

Posted by Leo Enticknap (Member # 534) on 11-05-2001, 10:37 AM:

I've always understood the 'nitrate look' to be caused by the higher silver concentration in the emulsion than to the optical properties of the base itself.

About 3 years ago I saw a nitrate IB print of 'The Life and Death of Colonel Blimp' at the NFT in London and remembered thinking that the characteristic crisp and dense look which characterises b/w nitrate just wasn't there. In fact, the print was very soft and flat, and the explanation I was given was that IB printing was such an expensive process that (especially in wartime) they couldn't just discard the prints where the matrices didn't register quite right. Instead they were designated as 'North of Watford' prints [Watford is a suburb in North London], i.e. they went to the provincial and second-run venues. Getting back to the point, none of the IB nitrate prints I've seen have had the characteristic 'glow' of the b/w ones, which leads me to believe that this look does not come from any intrinsic property of the base.

As for orthochromatic vs. pan, the studios made the change to pan in the late 20s (i.e. 20 years before nitrate was phased out), so would anyone really think that the 'nitrate glow' was a characteristic of ortho stock? I don't think I've ever seen any nitrate prints projected of anything as far back as the 1920s.

When it comes to copying, the better the element you start off with then the better the dupe will be. There was a re-release of 'Mildred Pierce' over here about three months ago: the new prints were made (according to a contact at the BFI, who handled the rerelease) from an interneg which in term had been struck from a f/g dupe pos which in turn had been contact printed off the cut camera negative, which survives in almost perfect condition. In other words, these prints were no generations further removed from the camera negative than a print of a new production would be, and every stage of duping was done by contact printing. The result was fantastic - the sharpness and density in those prints is something you very rarely see nowadays, even in prints of newly made films. It was the nearest I've ever seen to a 'nitrate glow' on a safety stock, and certainly better than some nitrate prints I've seen.

Posted by John Schulien (Member # 215) on 11-05-2001, 11:49 AM:

Leo -- why would you not run a valuable print through a flying-spot telecine? Is this sort of machine particularly dangerous to film? I thought that a flying-spot telecine was really a glorified scanner, and wasn't dangerous to film, but I've never seen one in person.

I've also noticed older IB prints that have a "soft" look. It seems more common with films shot on the old three-strip negative cameras, as opposed to films shot on color negatives.

I'm guessing that either:

o the three-strip cameras produced negatives that weren't as sharp as color negatives, due to the extra optics involved in splitting the light, or

o Improvements in the dye transfer equipment over time resulted in sharper prints, or

o The dye transfer process at the time was designed to allow the dyes to slightly migrate, thus concealing the film grain at the cost of a slight loss in sharpness.

Posted by Jerry Chase (Member # 660) on 11-05-2001, 12:08 PM:

Interesting. So are you suggesting that the difference is primarily one of contrast range, and the dense silver provided "blacker blacks?"

If so, I would think that ambient light would have a greater effect than it does. I remember showing some nitrate short subjects at a drive-in, where there is plenty of stray light, and the image was still outstanding compared to normal fare.

I wonder if the printing process might have more to do with it than I had previously suspected. Was the printing of nitrate done differently? Did a high-speed dupe process come in at about the same time nitrate was phased out? The crispness of the image is a definite difference AFAICT.

I also wonder how panchromatic the early pan films actually were, and if filters were in greater use to "pop" the sky or contrast in some scenes.

Posted by John Pytlak (Member # 331) on 11-05-2001, 01:27 PM:

I tend to agree that the "nitrate look" was probably more a matter of the tone scale of the emulsions used, and how they were processed. AFAIK, cellulose nitrate and cellulose triacetate base are not that different in their optical characteristics (see the Kodak paper "Improved Safety Motion Picture Film Support" by Charles R. Fordyce, Journal SMPE, 51:331-350, October 1948).

FWIW, with a well-exposed color negative, it is certainly possible to obtain black densities higher than 4.0 (10,000:1) on KODAK VISION Premier Color Print film, which would likely exceed the d-max of any B&W print film of that era:
http://www.kodak.com/US/en/motion/products/lab/2393.shtml

Another thing to bear in mind is halation. Modern film stocks have much better protection against halation (light reflecting from the backside of the film after it has passed through and exposed the emulsion) than films of that era. Halation can look like a "glow" around light objects in the scene.

------------------
John P. Pytlak, Senior Technical Specialist
Worldwide Technical Services, Entertainment Imaging
Research Labs, Building 69, Room 7525A
Rochester, New York, 14650-1922 USA
Tel: 716-477-5325 Cell: 716-781-4036 Fax: 716-722-7243
E-Mail: john.pytlak@kodak.com
Web site: http://www.kodak.com/go/motion

Posted by Will Kutler (Member # 770) on 11-05-2001, 05:48 PM:

Hi John Pytlak!

I always loved the extra rich colors that were common of nitrate films! It really leads to the ambviance of the picture! I had some questions about this and e-mailed you some time ago but never heard back. Wonder if you got my message? I am glad that this topic was brought up!

An off the wall question for you? In your acient library vaults at Kodak, would you have any books for the Kodak Pageant 16mm projectors, maybe nos parts? I always thought that these were neat little machines.

Posted by Dennis Atkinson (Member # 345) on 11-05-2001, 06:24 PM:

To answer the question about mylar preserving the nitrate glow,
It does, only a little though, far more than other stocks.
The film base is part of the "glow", I believe slower processing, more silver, and the carbon arc light source added to the look.

I did run a newly restored, fresh out of the lab Clara Bow silent two years ago. It was on mylar and from the original negative.
It looked great.

Dennis

Posted by Michael Barry (Member # 237) on 11-06-2001, 07:48 AM:

Leo: I ran a print of the re-released 'Mildred Pierce' and agree with virtually everything you said regarding the quality. It was absolutely stunning! The only prints I've projected and/or seen that were at that level of contrast/density were Fritz Lang's 'The Big Heat' (Columbia Pictures' 75th Anniversary) and the French classic 'Jeux Interdits' (Forbidden Games).

Posted by Leo Enticknap (Member # 534) on 11-07-2001, 05:35 AM:

John S - I agree that a flying spot telecine is actually a lot kinder to film than most projectors. But archival practice dictates that an original status element is not run through any sort of machine at all apart from a printer to make further copies. The preservation rules used by most archives assign a category to elements in their care. A typical system would include the following categories:

Master status elements - Can only be used to make printing status copies. Examples: the cut camera negative of a major feature film, or a fine grain dupe pos of a nitrate original which has been lost through decomposition. If a release print is all that survives of a title, then it will also be assigned master status.

Printing status elements - are used to produce viewing copies. Example: an interpos made from a surviving camera negative, or a dupe neg made from a master status fine grain pos. The use of these elements is less restricted than master status ones.

Viewing status elements - are release prints used for projection and telecine. There is no need for any technical restriction on the use of these at all, becuase the master status elements are already doing the job of preservation and printing status elements ensure that you can make further release prints as needed.

Surplus status elements: where you have acquired multiple elements of the same title and selected the best for preservation (and so assigned master status to it), the remaining elements can be categorised as surplus (i.e. they're not needed to ensure the long-term survival of the film). Let's say for example that an archive acquires five release prints of the same film, but no pre-print elements are known to survive. These prints range in quality from very good to quite worn. The very best print is used to re-record a new sound negative, and then sections from the three best prints are combined to produce a new master element. Preservation dupes will be made from this, and at the end of the whole process the cut original element plus a preservation dupe neg are assigned master status. Now there are two uncut prints left, and because these are not needed to safeguard the film, they can be used for access purposes and so are assigned surplus status.

Following recommended archival practice, this is the only scenario in which I could envisage a nitrate element being put through a telecine (or projected in a cinema). Doing so with a master status element is just too risky: if the stock accidently tears during the transfer (e.g. if there is a mechanical failure in the telecine machine) then the only surviving film element is damaged forever. And if the very unlikely event happens that it does ignite, then you've lost a whole reel of the film forever and can never get it back.

Michael - funny you mentioned 'The Big Heat', becuase there have been some other really good Lang rereleases over here too, including beautiful prints of 'Scarlet Street' 'You Only Live Once'. Hardly light entertainment, though! Not surprising the poor guy went from making megabuck epics in Germany to ending his days on no-budget 'B' movies.

Posted by Christopher Seo (Member # 7) on 11-08-2001, 10:12 AM:

I noticed Edmund Scientific selling pellicle mirrors, which I understand are used in converting old movie cameras to reflex viewfinding, which are made of "nitrocellulose". Assuming this is indeed the same stuff as the film base, I was wondering why a flammable material would be used... unless it had some especially good optical properties.

Posted by John Pytlak (Member # 331) on 11-08-2001, 10:57 AM:

Christopher Seo asked: "...made of "nitrocellulose". Assuming this is indeed the same stuff as the film base, I was wondering why a flammable material would be used... unless it had some especially good optical properties."

Yup. Same nitrocellulose used for nitrate film base. Note that it is "select optical grade" and only 2 micrometres thick. Doubt it would be subject to ignition. If it did catch fire, a 2 micron pellicle would go up like magician's flash paper.

Posted by Stan Gunn (Member # 554) on 11-10-2001, 02:02 AM:

I have a collection of nitrate spanning from 1900 to the end of nitrate, approx 50% is still runnable on a projector.
due to the dense silver laden image black is black, the tones from black to white is in my mind the main reson for its screen appearance.

Of course carbon light also ads to the glow,even if it is only 45 amps. Look at nitrate made in the 50s the silver content is much less as what was black is very dark gray, carbon arc in my open air theatre rules supreme even with 16 mm.

Arc is the best light, HELLZAPOPPIN leaps of the screen as it gently waves in the summer breeze.

------------------
ALL PARTS FOR VICTOR AND KALART VICTOR 16MM PROJECTORS.
SERVICE TO 35 AND 16MM
PROJECTION EQUIPMENT.

Posted by John Anastasio (Member # 607) on 11-10-2001, 09:19 PM:

I've never seen a nitrate print projected with a carbon arc, but I can say that I've always preferred the look of carbon. It would be nice if B&W was still printed with silver. I just came from a showing of "The Man Who Wasn't There" and I found the color shift between reels (plattered...no changeover) a bit annoying. Since you can't get all the color layers to behave precisely the same way across the entire density range during exposure, the grey shades tend to turn various colors depending upon the density of the image. The overall result is a constantly shifting range of tones throughout the image. Darker tones tend to be cooler than the greys, which take on a distinct brownish tinge. It's not pronounced, but it's not B&W either. I once made a b&w "contact" print by running a negative "bi-packed" with unexposed stock through a camera pointed at a white card to get a projectable piece of film. Okay, okay. I was young and stupid...but it worked, although I can't for the life of me remember how I got that film loaded in there. Then again, I don't remember much from that entire year.

Posted by John Pytlak (Member # 331) on 11-10-2001, 10:41 PM:

For best color, color print film is designed to have slightly "warm" highlights and slightly "cool" shadows. Great for color, but slight tint for true B&W images. Noticeable when they mixed B&W and color print film in "Schindlers List".

Posted by Leo Enticknap (Member # 534) on 11-12-2001, 02:14 AM:

I'm glad it wasn't just me who noticed the colour shift on 'The Man Who Wasn't There' - thought my eyes were going funny!