slide film ..
good luck with that !
i am not sure how you work with your slides
but if you use other than analog methods you will be fine ..
but some people say " cold stored " and it is just BS
i don't store anything in the freezer or fridge, just on a shelf in a box
or boxes ... b/w .. i shoot pretty much only expired film and
can't tell the difference between "fresh/store bought/recent purchase" and shelf stored
( and i am talking tmz that was at least 12years old. color film, well i don't usually shoot much
but i do have a ton of expired c41/e6 and i don't care if the colors are messed-up.
if you do care, i wouldn't buy from some0ne you don't know but then again
pro film sometimes goes for hours in a 120ºF truck before it meets another refrigerator ...
and then if it is shipped, days in a HOT cardboard box .... and then hours on a door stoop in the sun
YMMV
john
B&W film and colour film have different aging characteristics, for that matter colour negative and colour transparency have different aging characteristics. As for pro film, that depends on the shipper and method, I worked in the courier business, and we had stuff that was packed in dry ice and kept frozen, shipped overnight, it got to it's destination and was still frozen, as long as the shipping time was 24 hours or less. So it is possible to ship refrigerated film in a similar container, and have it arrive still cold, ship the package signature required, and it will be delivered to the store directly, the receiver at the store signs for it, opens it, puts the film in the fridge. The big black diamond with the number 9 at the bottom generally tells the receiver that it's something they should open now, rather then next week.
With E6 you can't really do much with it, except view it or scan it, and if your viewing it, you want the colours reasonably close, that means a tree leaf that is green is green on the slide. If your scanning, then you can always colour correct to some degree, with C41 you can colour correct when printing or scanning, again to some degree. However if the colours are really whacked out, you may be sunk. TMZ is B&W and there you can get away with a lot more.
If you bought the film fresh, and dropped it in your own deep freeze, for E6 at 100ISO, six years past expiry is the outside limit where it would be worth using, especially at over $10 a roll for processing. You might get another year or two out of it, if you use a hybrid film/digital process for slides. If I were buying film from someone on this forum, and they said it was stored frozen from fresh, yeah okay. Fleabay or CL, you take a huge risk. Besides for $1.50 a roll,you can go into a camera store, offer them $1.50 a roll for their film that will expire this fall and probably walk out with all of it.