Sheets for long-term slide preservation
Since a while I am developing my slides and that's very, very nice.
I preserve my slides in stripes of 6 pictures each, using translucent paper sheets which are supposed to be good for long-term preservation.
Those are sheets of that special translucent paper, not really transparent at all, I don't know the name in English* (we call them pergamini).
To be exact, I use the sheets #2510 in the Kaiser catalogue (this is the number of the 100 sheets package, the 25 sheets package is catalogued with number #2515).
I read now on an Italian forum that substances used to make the paper "transparent" might pose a risk for long-term preservation of the film.
Knowing the vastness and depth of the knowledge available in this forum, I'd like to pose a few questions:
- Are translucent paper sheets really dangerous for film?
- Were all translucent papers created equal, or is there the bad, the good and the ugly?
- What about Kaiser #2510 specifically?
- If my sheets are not advisable for the long term, what should I buy? Which kind of plastic exactly? And which maker, model? I know anything containing PVC is to be avoided, but it's not easy to know the material sometime.
* EDIT: This is what I use:
It seems the material used is called "glassine".
OK I searched in APUG for "glassine" and found a lot of material to read.
Thanks for asking this question Fabrizio, I love transparencies too and am wondering the same things regarding my own. My 4x5 chromes come back from my local lab in seethru clear plastic sleeves, so I wonder if I should leave them in or rather put them in "pergamin" sheets.
I've been reading contrasting information about the suitability of glassine material for long-term preservation.
Glassine is probably, generally speaking, good enough for most environments and needs (will last for many decades with possibly a bit of browning, but no damage to film normally). Some materials are better than other materials, but overall is decently good stuff. The only caveats relate to glue in "seems" and applied pressure in case of relatively high humidity. One should not put the "seam" over the emulsion. That might mean turning the film so as to put the support side in "touch" with the seem. 135 filers don't have this problem as film is preserved in stripes and the seems run parallel to the film.
The other problem is pressure. If pressure is applied, high humidity content might cause the glassine to adhere to the film. That's bad. I keep my sheets in vertical position (vertical "office-style" ring binders) so that shouldn't be a problem.
In any case, glassine is not compliant with ANSI IT9.2 - 1991, actually that old revision of the standard adviced against "acid-free" glassine as well, so even if it is a "good enough" solution for many decades according to many "real-life" reports, it's not the best in town. The current version of the standard is ANSI 9.16 and I don't know what it says in regard to glassine.
I will search what the market offers for alternatives. Uncoated transparent polyester (such as Mylar) seems to be, according to Wilhelm*, the best solution but not the cheapest. Uncoated polypropylene is also good. High-density polyethylene is also "probably" good and it is one of the cheapest solutions. ALL those plastic solutions struggle with static electricity problem (they attract dust) whereas paper-based product (such as glassine) do not. Besides, you can write with a pencil or a pen on a paper or glassine sheet.
Anything containing PVC or chloride compounds must be avoided. Low-density polyethylene is also to be avoided. From what I gather, the devil is in the details, any coating or glue has the potential for damaging film, more than the material itself are the "accessory" substances that cause problems. Sometimes the material is certified as being standard-X compliant, but the final product (which includes coatings and glues) is not.
I don't have a humidity problem in my house, and have decades-old film in perfect condition, but I am selling my house so this might not last.
I found this polypropylene solution which seems not expensive, I don't know yet if it is available in Europe:
This is declared to be complying with ANSI IT 9.16 so it's archival in the proper sense. At around $ 0.5 per roll it's not cheap but it's acceptable.
I still have to find a polyester solution.
I will probably go on with my glassine sheets until I sell my house and move. By then I will re-evaluate humidity, space etc. and maybe migrate all films to another solution.
* The permanence and care of color photographs, by Henry Wilhelm and Carol Brower, 1993, available as a free PDF on the net. The book is full of knowledge and first-hand experience, but it's 20 years old and is very much based on products available in the market at the time rather than on "theoretical" properties of materials. Progress in the intervening years might have changed things a bit.
Thanks a lot for all these info Fabrizio!
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I have negatives that apparently have been stored in glassine sleeves for about 75 years, and still are in fine condition.