Thanks John.
I asked, because many of my Agfa CT18 slides are so afflicted with various shades of green and deep purple colour castes that they are well beyond recovery - even to B&W.
My Kodachrome slides are still OK - OK that is if you can live with their blueish caste and how Kodak colour "science" of the day was baked into the film and presented to Kodachrome users.
I am not sure, Hugh. I am now working on a digital restore only because a part of the original slides got lost or damaged beyond repair.
Example of the original.