Thanks for that info Michael...you might be interested in the Preservation Calculator software that the IPI offers free online, and the pdf booklet for the "IPI Guide To Acetate Film Storage" as well... You can use this to gauge the effects of temp & humidity on the lifespan of a material...even though it's aimed at acetate based negs and vinegar syndrome, you can extrapolate data from it to get a rough idea of what sort of environment you need for your storage areas. Cold storage is the way to go though.... We have dedicated facilities for our collection (250K or so items), which are mainly 3-d objects, furniture, textiles and paintings. These objects all require different storage environments. Our photos are documentation of the artifacts primarily, and some originals like older cased images and an odd assortment of prints....our state archives though has something like 1.5 million negs and a cool room/ cold room for nitrate storage. We basically store our working files, some 60,000 or so negs & slides in a small room shut off, with a hydrothermograph in it to monitor the temp & rh....it stays at 65-70 and around 20-30% rh. It's hard to isolate an area without a dedicated vault though, and you can't really use traditional heating & cooling systems for this on a large scale....you need to be cool/cold yet really dry at the same time...and not cycling all over the place. Our building has a different sort of HVAC system that sorta heats & cools at the same time...it constantly regulates the temp & humidity and this is what alot of museums use because for artifacts you need to hold that at a certain level consistently. Probably the absolute worst thing that could happen to your prints & negs would be to have mold infect them ....When you talk with conservators though, they have a different angle on it than maybe an archivist, or a curator...they're all different professions in the same sort of business. The conservator is going to come in after the fact--the object is already in a collection, or has been brought to them. In an institution, the three all work together though to manage the collections....we have conservators for textiles & furniture mainly here....I can tell you that the minute an item becomes part of a collection it moves into another area of storage & display that is far beyond what the average person would think. For an individual to just assume that their fiber based print will last forever, is just a fantasy really...for that print to last 4000 years (sorry, still cracks me up) that would mean somebody, or someplace would have to become the caretaker for it....somebody would have to _really_ want it...out of all the quadzillions of images ever produced, I wonder what the number will be to actually survive? Especially when some places will spend up to a million or so on a vault, and then have to prioritize what images deserve to be saved, because you can't save everything.....if you really start adding up the costs for sheer amounts of materials, and care like the services of a professional conservator, it's mind boggling almost....and then multiply that times the size of your photo collection....if you took all that money you spent on "archival" materials, and built a vault or rented space underground, you could in fact save your images for a long time even if they were stored in not-so hot enclosures....but then who'd ever see them?

as always MY opinions only here.

p.s....

You also might be interested in these week-long seminars that the IPI offers....I went to one 5 years or so ago for work up in DC at the Smithsonian CAL lab. It was sponsored by them, but there were with archivists & conservators with NARA, IPI etc. there. It was about preservation issues in photo collections, They still give these annually up in Rochester, but the CAL gives other seminars as well. Some other institutions like NEDCC offer courses in presevation management as well.