Nothing Ambiguous about apparel company's growth. (Up Front).

Talk about due diligence.

When apparel industry veteran Don Kerkes was looking to invest in Irvine clothing upstart Ambiguous Industries, he turned to his teenage daughter.

"She said, 'Yeah, Dad, it's the new hot brand,'" Kerkes recalled.

The clincher: a Christmas party put on by Ambiguous founder Frank Delgadillo at a local club. Early in the evening, 11- and 12-year-olds were hanging out. By 9 p.m., the place was jammed with hundreds of 20-somethings. Outside, a big line of people waited to get in.

"Twenty-five percent or more were wearing Ambiguous clothes," Kerkes said. "They created this brand that 11- and 12-year-olds love, and 21 and above believe in, too. You have an opportunity to sell to a pretty big cross-section of kids."

Kerkes, former sales vice president for the men's division of Santa Monica-based Mossimo Inc., was sold. He joined Ambiguous in 1999, a move that marked a shift for the company Delgadillo founded in 1995 while he was studying pre-law at Chapman University.

"With Don's expertise and our knowledge on how to keep the design concept authentic, it was the perfect match." Delgadillo said. "That's the downfall of most small companies. They don't have the expertise."

Abiguous remains small. Industry sources put sales in the range of $2 million to $5 million (though company officials say those figures are low), and there are only 15 employees.

But Ambiguous is hot. The company falls somewhere between big surfwear makers like Huntington Beach-based Quiksilver Inc. and more trendy designers such as Newport Beach-based Paul Frank Industries Inc.

Outlets grow

In six years, the number of stores offering its T-shirts, hats, jackets, jeans and other products has grown from 50 to 500. Along with domestic sales, the company also ships to Japan, Canada and, just recently, South America and Puerto Rico.

"Buyers are always looking for what's next, and Ambiguous has been one of those 'what's next' brands," said Darn Dennee, publisher at Laguna Beach-based ASR Trade Expo.

Until now, Ambiguous has worked off word-of-mouth buzz from having rock bands like Alien Ant Farm and Black Eyed Peas sport the company's clothes. But Seattle-based Foundation has been tapped to develop the company's first marketing campaign.