I have a box of Supra Endura F, and one E that were aledgedly kept frozen, but long expired. One worse than the other. Although I am able to manage the color filter pack and get the colors right, the paper shows it has yellowed. This can be easily noticed in highlights, whites and unexposed borders. What can I do ? I throw a bit more blue to counteract but it is still litle help.

What else can I do ? any chemical process out there that could help .