Had a darkroom Printing Session with some 2008 dated Ilford DELTA 400 Pro taken in my Yashica FR-1 which I had processed in home-Made ID11 1+1 for recommended time 14 mins and negs came out dense and over-developed ! The ID11 has suffered from 'Increase in Activity' Luckily I had Grade 1 paper !
It could of course be your scanner but the scan of the print looks remarkably grainy, Pete. If the negs don't exhibit more grain under a grain focuser than is normal for D400 then I suppose it might be the fact that the paper is also old.
Do you see the same and if so what do you think is the cause?
I think it was also the fact that my ID 11 had increased in Activity and all negs were over-developed. Also -- that batch of film ( I have 2 Cassettes) came from a Huge Stash given to me by Sons of my Deceased Great Friend of over 65 years.