What make-up technique was used to preserve Jack Nicholson’s grin as the Joker on the original Batman movie? ?

Question by Javier M: What make-up technique was used to preserve Jack Nicholson’s grin as the Joker on the original Batman movie? ?
For Jack Nicholson’s Joker grin, were prosthetics used? Was his face freeze dried as original rumor has it?

Best answer:

Answer by The Drat. Penny Dreadful
I’ve never heard that ridiculous rumor.
I’m assuming it was a type of foam glued to his face, then they painted make-up over it.

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