By Darcy Brown-Martin

If you've ever stared out the window of a jet landing in Oakland or San Francisco, you've probably glimpsed the South Bay's crazy quilt of salt ponds. It's in these colorful flats that Cargill Salt—the world's largest marketer of the world's favorite seasoning—traps murky bay water and lets it evaporate in the sun, yielding up to 600,000 tons of salt each year. Dave Merriweather, Cargill's technical director, gladly stands up for his product.

Q How long does it take to make salt from bay water?

A It's a long-term process. From the time the water enters our pond system to the moment we scrape the solar salt from the crystallizer beds takes five years.

Q Can salt from bay water possibly be clean?

A We redissolve the solar salt, purify it, and run it through evaporators, and it comes out looking like ordinary table salt. It's 99.8 percent pure.

Q Is it purity that makes your salt so good

A We have specifications saying it has "characteristic saline taste." That is, it tastes salty.

Q Which tastes better, white salt or colored sea salt?

A Some of the colored salts have a flaky texture, which changes the way they dissolve in your mouth—it happens toward the front. But the color in those salts comes from impurities that can impart an astringent flavor.

Q What about kosher salt?

A It's a coarse white salt produced according to Jewish dietary guidelines. It combines the purity of table salt with the flakiness of sea salts. Lots of culinary people use it because it adheres to food differently and dissolves differently, so it has a different flavor.

Q And if we saw you with a saltshaker, you'd be . . . ?

A Topping french fries.