The Oscar-winning prosthetic makeup artist is the frontrunner again this year for multiple feats of makeup mastery and pushing the limits of his craft.

Oscar-winning prosthetic makeup artist Kazu Hiro (“Darkest Hour”) has become a wiz at tackling real-life celebrities, and he’s the frontrunner again this year for achieving multiple feats of mastery on Jay Roach’s “Bombshell”: transforming John Lithgow as Roger Ailes, the late Fox News honcho forced out for his predatory sexual harassment, and producer/co-star Charlize Theron as former anchor Megyn Kelly.

Yet the challenges and obstacles were so great that Hiro and his Oscar-nominated team (Vivian Baker and Anne Morgan, heads of makeup and hair) were required to push the limits of their craft. That’s because Lithgow and Theron don’t very much resemble Ailes and Kelly. And while the strategy for transforming Lithgow was not a precise recreation, Theron wanted to look as much like Kelly as possible.

“When we do likeness makeup in a film, it’s always a question of how close they want to make the actors into the actual person, and they asked me to do a hybrid between Roger and John,” Hiro said. “Because I mentioned to [Jay] that whatever I do on John, he won’t look a 100 percent like Roger because the proportion of their shape is so different. But I told him I can put the essence of Roger on John. At the same time, I had a meeting with Colleen Atwood, who was the costume designer, and discussed making the body suit and wardrobe at the same time.”

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At first, Lithgow didn’t want prosthetics because of a bad experience, but once he started working with Hiro and discovered how soft and comfortable the pieces were, he was all in. But there was a lot of work to create the essence of Ailes for Lithgow. Aisles had bulldog cheeks, a bigger nose, thicker lips, a different hairline, and the shape of his forehead was round, whereas Lithgow’s is almost triangular.

On top of that, Hiro was informed that the application time needed to be as minimal as possible. “I decided what I could put on John without preventing him to make a subtle expression,” added Hiro. “In this case, I tried to open up around the eyes so he can use his eyes freely and also around the mouth. But, if I put lips on John, it will make it harder to talk and it won’t move well and there would need be a lot of touch up on set.”

The best solution involved individual pieces for the neck, cheeks, nose, and earlobes. Hiro also shaved the hairline back for Morgan to take over with necessary coloring and alteration. “And style it in a way by cementing the top down to be as flat as possible so the sides could appear wider,” she said. “Little things that just help the eye get more adjusted to an overall silhouette.”

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With Theron’s delicate transformation as the popular and recognizable Kelly, she required a whole other set of demands. “Charlize has a soft, round face, and Megyn has a strong, angular face,” Hiro said. “They have different [noses] and Megyn has heavier eyelids.” Therefore, a nose plug and tip were important, and, additionally, jaw and chin pieces helped reshape Theron’s round face to Kelly’s square shape.

“Charlize’s makeup is much more complex,” Hiro added, “because her skin is so smooth and translucent, and anything we put on and tried to match to her natural skin was fine, but applying beauty makeup changed the sheen and the color right away.” Baker then took over with the added difficulty of applying beauty makeup on top of the prosthetic, which changes the element.

“It was complicated at times,” Baker said. “We had the newscaster part of it to do because that was part of the makeup on her face. Kazu would mix up the sealer and then I would have to develop different types of makeup that could go over it, and everything would go on a different way. It was like a mad scientist building different things, but not as revealing as Kazu’s prosthetics.”

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Hiro said they pushed their limit with Theron as Kelly. “We tend to avoid this kind of makeup because each piece is so small and was hard to maintain on set,” he added. “You see right away if it’s not applied well. It has to be applied in the exact position every day. And the eyelids were hard. I was able to use scanned data to make another life cast of Charlize to sculpt just the eyelids. But I changed it six times.

“I think Charlize is really brave to accept doing this and wearing prosthetics,” Hiro said, “because most actresses don’t like to have pieces glued on and become different persons.”

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