Preserving Original WW2 Letters/Photos

[tdracer]

I was just visiting my sister, and she reminded me that, when our mom passed 10 years ago, she took possession of a box of letters that my dad wrote to his parents while serving in the South Pacific during WW2. He was part of the 164th Infantry, and saw action on Guadalcanal (Purple Heart), New Guiney, the Philippines, and was part of the occupation force in Japan after the surrender. Some of the letters are heavily censored, but are historically very interesting.
My sister wants to preserve those letters - not just scan them (which we also plan to do) but to preserve the originals. The letters are in surprisingly good shape, especially considering they are over 70 years old, and somehow providing high quality, (and very lightweight) paper for the letters home was not a high priority for the military at the time.
She's doing the obvious stuff, keeping them in a cool, dry, dark place in a plastic container, and I know we should probably be using gloves when we handle them. As chance would have it, my dad was the company intelligence officer on Guadalcanal and was permitted to have a camera - the surviving pictures are in my possession, I have plans to scan those as well and perhaps lone the originals to a museum.
Anything else anyone can add as to how to preserve these historical originals as long as practical?

[Heathrow Harry]

This is a very good summary:-:-

Preserving Old Photos and Documents (http://homepages.rootsweb.ancestry.com/~george/preserving_photos.html)
but also:-

WARNING!:
Archivists have discovered the hard way that using ordinary lamination plastic for old documents, newspapers, photos, etc., does not preserve them. The best way to preserve them is to store them in a dark place after placing in acid-free Mylar film (not laminated). Ordinary lamination material still permits light rays to pass through it and to cause a chemical reaction to the acid that most modern paper and modern dyes contain, and that ALL old documents photos contain. This causes deterioration of paper and fading of the paper and print. The heat and pressure of most lamination processes also damages documents.
Of course, keeping original documents is important, but one should always copy (scan) newspapers and other documents and then print them on acid free paper, which can be found at just about all stores selling printer paper and/or computer supplies. Too, one should save the graphics files from scanned documents and put the files on CDs for permanent safekeeping. Life expectancy for data on CDs is 80-100 years for premium quality CDs.

[pasta]

Life expectancy for data on CDs is 80-100 years for premium quality CDs.
Be very careful with digital storage for long-term purposes; the media itself may last a long time, but because technology moves at such a pace, the hardware to read it may not be available for as long as you might hope.

A good example of this was the BBC Domesday project in the mid 1980s, which captured a load of contemporary data (text, images, videos etc) and stored it on Laserdisc for posterity. As little as 15 years later there were concerns that, not only was it almost impossible to find working Laserdisc readers, but the file formats themselves were obsolete and couldn't be read by modern computers. Floppy disks have come and gone; CDs and DVDs seem to be on the way out, mostly being replaced by memory sticks.

The best idea I can think of is to save everything on CDs/DVDs, keep a copy somewhere online (mailing everything to a GMail account is an easy option), save it to a memory stick too, and then review every few years so that you have the option to copy everything to the next new technology before the old one disappears. Bit of a pain I'm afraid!