Selena Gomez debuted her new look at the American Music Awards on Sunday. Picture: Bang Showbiz

Selena Gomez's bleach blonde hair took "nine hours", eight bowls of dye, 300 foils and two hair experts to perfect.

The 25-year-old singer flaunted her newly dyed bob at this year's American Music Awards, which took place at the Microsoft Theater in Los Angeles, California, on November 19, and the star's beauty team have revealed the makeover took almost 10 hours to carry out as "eight bowls of bleach" and "300 foils" were used in "one sitting".

Speaking to Us Weekly about the transformation, hair stylist Riawi Capri from Nine Zero One salon said: "It took nine hours, about 300 foils, and eight bowls of bleach, all with two stylist [Riawi and Nikki Lee] working together simultaneously.

"It was a nice long patient process of baby fine slices, then going back and opening each foil and reapplying, but done in one sitting. Anything is possible in one day, it just takes time, no other clients, and patience to maintain the integrity of the hair."

And the experts made sure they did their utmost to ensure the 'Fetish' hitmaker's tresses remained "healthy" and the lighter hue complimented her skin tone, especially because it was Selena's "first major colour change" going from brunette locks to blonde. 

The salon's co-owner, Nikki, said: "Being that this was the first major colour change Selena's ever done, it was important to us that her hair remained healthy and the tone was right for her skin. The vibe is 90's chic and she named the colour.

"Now that Selena is blonde it's so important to keep her hair moisturized, strong and healthy. For an added dose of moisture she swaps out her regular conditioner for Pantene's Radiant Colour Shine 3 Minute Miracle Daily Conditioner. This keeps her rooted creamy blonde healthy and Selena can rock this new fresh look just in time for the New Year."