SO339 is the replacement for (not the same as) Kodak's 4168 "Direct
Duplicating" film. There were complaints about the SO339 (Palladio didn't
like it for their paper), but I've found it fine for my purposes -- though
painfully expensive. It was also handy in duplicating view camera
negatives that were too soft for non-silver -- longer development upped
the contrast.
I prophesy, however, that this too will be discontinued in the
not-too-distant future. Kodak sees its maximum profit in digital.
> The 16x20 film runs about $450.00 per 25 sheet box.
Or $18 per sheet.
Judy