Burger King is showcasing a nasty looking Whopper to promote the idea that it is dropping preservatives from its food.

The campaign, aptly called “The Moldy Whopper,” shows what happens if a Whopper is left out on a table for more than a month. Spoiler alert: It spoils. It underscores the chain’s decision to eliminate artificial preservatives from its food.

“The idea is the beauty of real food is that it gets ugly,” says Fernando Machado, Restaurant Brands International’s global chief marketing officer.

The campaign is a joint effort among Swedish agency INGO, David Miami and Publicis. It begins running in some European countries and in the U.S. on Wednesday.

The Home of the Whopper wants to be seen as more appealing to those seeking foods with cleaner ingredient labels. Yes—even people who scarf down a 660-calorie Whopper want to feel better about the food they eat. Eliminating artificial colors, flavors and preservatives is something Burger King has been working on for years.

Burger King, like other chains, typically showcases nearly flawless images of its food in marketing, even if the versions customers receive don’t arrive with perfectly prepared and placed ingredients. This glowing portrayal is how the Whopper in this campaign looks, at first. Then, the lack of preservatives sets in. The Whopper goes from gleaming to something no one should touch, let alone eat.

“We took a very different approach than usually what food brands do” to make the point that real food goes bad, says Machado.

One part of the campaign is a 45-second video set to the tune, “What a Difference a Day Makes,” sung by Aretha Franklin.

As the video progresses the bun starts to sag, along with the lettuce. Soon, the burger patty begins to turn white. Then greenish-blue. The bun and other ingredients follow suit. The video ends with the phrase “the beauty of no artificial preservatives,” a line that’s also in print and out-of-home ads.

The idea was years in the making, as Burger King began to remove artificial colors, flavors and preservatives from its food, following well-known products such as McDonald’s Chicken McNuggets and Kraft macaroni and cheese.

David Miami presented a version of the campaign idea about three years ago, before Burger King had introduced artificial-free elements in enough markets. INGO presented a concept a few months ago, when Burger King was further along and felt it could work. Coincidentally, Publicis offered “a lightbulb” for the language and approach to the premise, Machado said.

Now, Burger King is far enough along in major European markets and in parts of the U.S. that it is ready to promote its food overhaul. Rather than picking one agency to handle the work, Burger King engaged all three on the project. The end result “is an idea that’s mainly from INGO,” says Machado, noting it produced every asset of the campaign, shot in Sweden. “But it has a bit of an influence and a bit of help from David and Publicis.”

“Mold grows in a very inconsistent way. We had to work for several months, with different samples, to be able to showcase the beauty of something which is usually considered undesirable. I never thought I would become a specialist in mold, but that was required to make this one happen,” Björn Ståhl, executive creative director, INGO, said in a statement.

Burger King removed artificial preservatives from the Whopper in most European countries and is on the way to removing them across the United States. Artificial preservatives have been eliminated from Whoppers served at approximately 400 U.S. restaurants. The chain aims to be preservative-free across its U.S. locations by the end of 2020. It also says it has already removed colors and flavors from artificial sources from all of its core sandwiches and sides in European countries and across the United States. More than 90 percent of all of food ingredients in the U.S. do not contain colors, flavors, or preservatives from artificial sources. Burger King says it has also eliminated MSG and high-fructose corn syrup from all food items.