At last: the truth about Trump's hair

It's a question for the ages: just what is going on with President Donald Trump's hair?

A new book may finally have the answer.

Journalist Michael Wolff's Fire and Fury: Inside the Trump White House potentially reveals the candid truth behind the coiffure. 

Ivanka Trump loves to mock her dad's hairdo, says Wolff, and "often described the mechanics behind it to friends" to "comical effect".

It's a head-scratching combo, claims Wolff, of scalp-reduction surgery, industrial quantities of hairspray and a supermarket brand of hair dye.

Scalp-reduction surgery involves a surgeon excising the bald spot and stitching together the skin that still grows hair. Wolff says Trump's hair is then carefully combed over the remaining bald spot and fixed in place with liberal spritzes of hairspray.

The peculiar colour, Wolff says, is due to Trump's impatience: he uses Just For Men dye but gets bored while it's processing, and washes it out too soon, resulting in the odd orange tint.

Fire and Fury won't be on sale until next Tuesday, but pre-orders - and a long extract published by New YorkNew York - mean it's already top of Amazon's bestseller list.

In addition to its hair-raising facts about the Trumpian tresses, it reveals such juicy titbits as the tale of an advisor attempting to explain the Constitution to the new president.

Apparently Trump became bored by the time he got to the fourth amendment.

It also contains top aides slating their boss's intelligence: "For Steve Mnuchin and Reince Priebus, he was an 'idiot.' For Gary Cohn, he was 'dumb as s---.' For H.R. McMaster he was a 'dope.' The list went on."

The White House has decried the book, which Wolff says was based on 200 interviews with White House insiders, as "trashy tabloid fiction".