I've searched for past questions on this and got limited info. I have several unopened boxes of Kodak Rapid Fixer (2-part). Age is unknown as I got it second-hand....about four years ago. Anyone know the shelf life of this for unopened product? I looked at the first two, and there is a little sediment in the bottom of the large bottle now. I'd throw it out for general principals, but I'd hate to do that if it is still good. I also have some old Hypo Check around, and I never did understand if that ages too. The last resort is to use the Hypo Check to verify the fixer. Thoughts? Thanks, Dennis