Photo: All rights reserved.

Mandy Moore

Mandy Moore's tears cause her This Is Us prosthetics to "melt" right off of her face.  

The actress has won praise for her performance as Rebecca Pearson in the NBC drama, especially in the scenes in which she dons prosthetics to appear as an older version of her character.

While This Is Us has built up a reputation for including lots of tear-jerking moments, Mandy has now shared that she has to avoid crying too much herself in order to keep her make-up intact.

"(Applying prosthetics) takes four hours but it's worth it," she said during an appearance on The Tonight Show Starring Jimmy Fallon on Monday night. "But when I'm with the (present) side of the family it is tough because Sterling (K. Brown), Justin (Hartley) and Chris Sullivan are all such jokesters, they're all laughing. And I'm not supposed to move in my prosthetics too much - the more you move and talk and laugh - it loosens them up. And we realized very early on in the show, tears are the perfect solvent for removing the prosthetics... My face would start melting halfway through the day and (the team) are trying to spackle me together and keep me going."

Mandy went on to credit make-up artist Zoe Hay for doing such a good job on the prosthetics. And she divulged that season three of This Is Us, which premieres in the U.S. on Tuesday night, features a lot of fun and romance.

"It's a really good season. We are seven episodes into the season already and it's my favorite yet," the 34-year-old smiled.

During the conversation, host Jimmy also pointed out that Mandy is building quite the reputation for starring in highly emotional projects, especially as she also headlined 2002 flick A Walk to Remember with Shane West.

But the brunette star explained that she never had any intention of making a name for herself in dramas.

"I started with A Walk to Remember when I was 16. That movie has touched people and still continues to in a way that we never, ever expected. I'm totally flattered. I'm slightly flabbergasted that the sort of things in my career that I'm most known for, are making people cry. I never would have guessed that in a million years," she added.