Old Graded Paper Questions

I recently bought a ton of Kodabrome paper on impulse. Grades 1 through 5. I have been conducting tests, and for the most part, base fog can be removed with BZT and, where necessary, bleaching back.

However, grades 3-5 produce identical contrast results. Which leads me to ask...what causes a paper to lose contrast, and is it a process that can be reversed? Does the BZT in the developer conspire to cause this? Fortunately, they have all converged on a contrast level most likely to be suitable for most of my negatives (probably about 2-1/2). But I am curious to know what causes the different contrast levels (when manufactured) in the first place, and why do the papers lose this differential over time? I rather like pushing old film/paper to its limits, and want to learn more about what is going on. I would also like to know if other developers (than Dektol) could increase contrast.

I'd love to know why contrast goes in old paper as well. I find that to be almost always the case, and it's something I've often wondered about. It's every bit as true with VC paper as well - the Grade 5 end will always be lacking even if the Grade 2 is "normal".

My experience with BZT is that it will increase contrast if anything, as it restrains the highlights.

If you're really interested in pushing old paper to its limits, I would suggest trying a point light source in your enlarger. On graded papers, I reckon the increase in contrast from a frosted bulb (like a PH 211 or 212) is in the realm of 1.25 grades. That's quite significant, and in my experience can turn a relatively flat old paper into something that is easier to work with.

I just revisited this thread.....I am still holding my breath waiting for someone to explain why old paper loses contrast, and whether the phenomenon can be reversed.