Beginner question - curling nitrocellulose film

I recently found a cache of ~100 negatives, widely varying sizes, from the early

1900's. I would like to scan them, but have no experience with scanning film:

 

Am I going to burn the house down putting nitrocellulose film through a scanner?

 

If not....

 

The film is badly curled (think tubes, not arcs). It will flatten out (was

stored interleaved in a book), but curls immediately when taken out of the book.

 

I've been reading about wet mounting - would that damage this kind of film? Or

should I put it between 2 plates of glass? Or straight onto the scanner, with a

plate of glass on top to flatten it? I don't have a scanner yet, but am

investigating the Microtek 6800 or i900, or the Epson 4490 or 4990.

 

Any and all help appreciated - thanks!

Catherine Klatt

The Epson mounts will not help when it comes to keeping them flat. I have trouble with the normal curl of 35mm film. If they're of value, I'd really look into buying a Nikon V or 5000 scanner. Neither the Nikon or Epson scanners are hot, so they won't melt or burn. I'd be very reluctant to wet-scan nitro film, but I don't have any experience with it either. Be sure to observer standard archival procedures, like wearing cotton gloves, avoid light, etc.

Catherine, you might look into anti-Newton ring glass such as <a href="http://www.betterscanning.com/scanning/usinginsert.html">this</a>. You could tape the negatives down to it (not really sure you want to with these) or possibly make a sandwich out of two glass pieces in order to hold the film flat. Not sure what sizes you have or if they would fit here. I just posted the link as an example.

Catherine, I have scanned more than 1,000 nitrate negatives, mostly in the old Kodak 116 format (2.5 x 5 inches). I used a flatbed scanner with a transparency adapter. None of my negatives ever caught fire, but I didn't leave them on the scanner longer than necessary. You never know with old nitrate film.

 

My negatives weren't too curly. But nobody makes a film holder in that size, so I made my own film holder. You can make one out of cardboard that will hold a negative flat enough for scanning. Because I had such a large number of these negatives to scan, I made a sturdier holder using wooden sticks from veggie corn dogs. (They are like narrow popsicle sticks.) My wooden film holder has slots to keep the film flat.

 

Don't wet-mount the film or rewash it to flatten the curly negatives without experimenting on an expendable negative. I tried rewashing and drying an uncut roll of 35mm b&w film from the 1950s, and it recurled itself in the longitudinal direction. (In other words, it curled itself into a long, narrow tube.) When I resoaked the film to uncurl it, the emulsion slid off the film base and was lost forever.<div></div>

I've found that with 116 and 828 its fine to simply press the neg against my Epson 3200 glass with the flawless piece of 1/4" water white glass that once served as part of a contact print frame.

 

Focus difference Vs whatever's theoretically correct for the scanner is pretty much irrelevant because this is a relatively large format film that you're (probably) not planning to enlarge beyond letter size, if that. And flatbed defocus is not nearly as bad as the optics and diffusion source commonly used 100 years ago to make the original silver prints.

 

My old negs have usually been too uneven to result in significant Newtons Ring problems when simply pressed against the flatbed glass by another sheet of smooth water-white glass. They're not as smooth as modern large and medium format film any more, if they ever were. On the rare occasions when rings have shown up they have been fixed with Photoshop...takes time, but you'll be spending time like that anyway because the old negs will make other demands on you.

 

116 was a wonderful format, sometimes recording information that was missed in the optical prints of the era. Many negatives that expected to be useless due to silvering and other corruption resulted in better inkjet prints than the originals that I also had, revealing surprising things about my family...time travel. I especially like scanning and printing the old Kodak "autograph" negs that allowed the photographer to scribble notes about the shot through the paper backing, resulting in white writing on a black background at one end of the negative.

 

If the negatives are damaged from age and handling it's still worthwhile to scan them. Don't be afraid simply to uncurl the curled examples.

 

If you're brave, DO soak an occasional especially scummy or crusty example in warmish (warm room temp) water with Photoflo, then use your fingers to gently squeegee them (common practice in darkrooms for decades). In my experience with 100 year old film, the emulsion DOES NOT come off if you treat it gently in this fashion. Nonetheless, you may want to scan before you wash, just to be on the safe side.

Hi Catherine: Photo film consists of layers, mainly gelatine on one side and the film backing on the other. What causes the curl is a dimensional unbalance between the layers, a kind of tug of war between then in which each layer tries forcing the other into its own dimension. The stronger wins, i.e. makes the other follow. For example, at low humidities, the gelatine, -more hydrophilic, shrinks more than the backing and unless it was to separate from the backing, the only way it can shrink is by assuming the smaller diameter in a curl, where the backing assumes the outer, larger circumference. This is explained in the file "Newton Rings" at http://www.scanscience.com/TechLibrary.html.

 

With legacy films, the evaporation of plasticizers originally present in the backing can also induce the backing to shrink. If the unbalance from the shrinkage of the backing were to overpower that caused by a loss of humidity to the emulsion, the film would curl with the backing inwards. This is rare however.

After the disaster involving Nitrocellulose film, the type of backings changed to many other types of cellulose backings, and that brought about the so called 'safety film', in which case, the words 'safety film' will appear on the margins of the film. If indeed you have Nitrocellulose film, do be extremely careful. NC is a very dangerous substance. To demonstrate its power I once ignited (in the lab) about 1/4 of a gram of dry NC with a sparker and the result was a sudden explosion somewhat smaller than a gun shot. I used NC then to make wood lacquers, because when wet or mixed with other resins it looses its dangerous properties. In film curling can be controlled by adjusting humidity. The way of doing this is explained in that file.

Be patient, it is doable but it can take time. Regards.

Nitrocellulose is still used to finish the finest custom-built guitars...said to be the finish that least affects the wood's tone.

Thanks, everyone, for your wonderfully helpful suggestions and explanations. I have printed everything out and am reading it carefully. After I get started I will report back on what works and what doesn't (and on how veggie corn dogs taste).