Pair a Vince plaid shirt with a Gap denim jacket for the right mix. (Chris Walker, Chicago Tribune / March 10, 2010)

Ever the lightning rod, denim is crackling like it did at the dawn of $200 jeans. Gap, H&M, Armani Exchange, J.Crew, Banana Republic, D&G, American Eagle and others are turning head-to-toe denim into one of spring's most noticeable trends, one that knows no gender bounds.

For guys, fashion changes at a plate-tectonics pace. So going from a pair of jeans to jeans, a jean jacket and a denim shirt — all in one wearing — can look drastic, in the same way that Brad Pitt's backwoods beard seems a bit much, even in the midst of a facial-hair frenzy.

Not to Patrick Robinson, a design alumnus of Armani and Perry Ellis who now is creative director of the Gap.

"Denim is a huge, huge way of expressing yourself right now," he said. "Obviously, wearing all pieces of it makes you that much cooler."

But, "There is a trick to it," he acknowledges.

Proceed with caution

Robinson isn't talking — or walking — the Jay-Leno-with-his-cars interpretation of double denim (roomy blue jeans with a chambray shirt). Nor is Robinson advocating the jumpsuit look mocked as the "Canadian tuxedo" after the 2001 movie "Super Troopers" featured a character named Denim Dan.

"The trick is you don't want to look like you're wearing the same denim on top as on the bottom." Instead pair a darker and lighter wash, said Robinson, who often wears a white T-shirt with dark blue jeans, black motorcycle boots and a "really, holey, distressed (lighter blue) old denim jacket."

Nick Sullivan, fashion director for Esquire magazine, agrees on the need for contrast — and caution.

"There's a very famous picture of Steve McQueen shot by William Claxton of him wearing a denim shirt and denim jeans that match," Sullivan said. "That was the '70s. And that was Steve McQueen, more importantly. The problem is, when everyone else does it, it can be a bit John Denver."

If you're going to double up on denim, it's safest to keep the color of your top half lighter than the bottom, Sullivan said. "A darker shirt on lighter jeans doesn't work. It has something to do with the visual center of gravity."

Some say steer clear

The authors of the new book "Undateable: 311 Things Guys Do That Guarantee They Won't Be Dating or Having Sex" say they know the trick to double denim: Don't do it. Ever.

Ellen Rakieten and Anne Coyle rank "double denim" No. 20 on their list of deal-breakers, right up there with tube socks, Transitions sunglasses and owning a cat. They define double denim as a denim shirt or denim jacket worn with jeans, "which gives the illusion that you're wearing a denim jumpsuit."

"We know you love them both, but you're going to have to choose one or the other," they write. "And don't go thinking that you can get away with substituting a chambray shirt for a denim one, either. They're the same thing."

How to pull it off

Designers at Gap-owned Banana Republic advise the all-denim wearer to consider the cut of their jeans.

To keep it modern, steer clear of a relaxed fit.

"We're talking a slimmer fit or vintage fit that has a skinny-leg look," said Banana Republic creative director Simon Kneen. Limit the distress of the jeans; lean toward the "just worn-in with a tiny hole here and there."