Quote Originally Posted by TheToadMen View Post
I'm not sure but if I remember correctly the Kodak BW400 film (= B&W film for C-41) has also a brown base?? I'm not sure but can't check it right now.
You could develop an unexposed part of the film to see what colour the base is in itself.

It not the Kodachrome film base color you see, it's the CLS (Carey Lee Silver) that is colloidal silver used as a yellow filter layer.