I have a set of Ilfochrome printing filters that I've been trying to use for RA-4 printing. The filters are probably 20 years old or more.
I'm using fresh Arista chemistry and fresh Fuji Crystal Archive paper, but having a heck of a time getting the color balance even close. I'm using a standard condenser light source in an old Omega ProLab enlarger. (GE PH211 bulb).
I'm ending up with a filter pack around 0.2M and 0.2C (no Yellow) which seems very strange.