See 'The Watermelon Man'
I watched "The Jazz Singer" last night and the blackface reminded me of the movie "The Watermelon Man" (1970). It's the same thing as blackface, only in reverse.
And someone's idea that blackface wasn't a convention of the times and not consciously racist is ridiculous. Ask a black person (i.e. read a testimony) from that time if it was racist or not. Or, better still, ask a fat person today how he/she feels about somebody wearing a fatsuit.