Good Hair (2009)

There are things in Good Hair, Chris Rock's deeply funny and very serious documentary about the African-American obsession with straightened tresses, that may make your hair stand right up on end. Here are a few of the movie's fascinatingly fun facts:

· The hair ''relaxer'' used by African-Americans for many decades is sodium hydroxide, which will eat away a soda can in two hours and leave you with permanent bald spots if it seeps into your scalp. (Peering into an 18,000-pound vat of the stuff, Rock remarks, ''This would last Prince for about a month!'') The asymmetric hair that Salt-N-Pepa made iconic was the result of a relaxer accident.

· The weaves that are now legion among African-American women can easily cost the most modest working-class folks $1,000 a pop. Those high-maintenance 'dos have become an integral point in the politics of black dating.

· The next time you see an artist like Eve or Nia Long (both interviewed in the film), there's a good chance that the hair they're wearing once belonged to a woman from India who cut it off in a religious ceremony.

Rock, who co-wrote Good Hair and serves as its guiding host, is hilariously aware of the cultural insecurities that have driven many African-Americans to spend a fortune on straightening their hair. Yet by structuring the film around the Bronner Bros. Hair Show, a battle-of-the-salon-stars so over-the-top it's like Iron Chef meets Paris Is Burning, Rock gives Good Hair a rousing message: Where African-Americans in the '60s adopted a ''natural'' look, they now feel free to coif their heads any way they want. That's cultural power.