last century's photo paper

[HuubL]

I recently got quite a bit of photo paper from a photo lab clean-out, mostly PE, RC Brovira Speed and Kodabrome IIRC. It's all pretty old stuff from the 1990's, although most boxes have never been opened and always stored in a dark cabinet. Anybody has any idea how long this stuff lasts? Can I still use it? And in 10 years time? I checked at APUG, but couldn't easily find an answer.
Thanks for your input.