EVERETT — For science, she shed a few tears.

Hai Evans wanted to support her son Rowan, 11, as he worked on inventing The Onion Shield.

She kept cutting onions using his prototypes of the stainless steel device, meant to block harsh vapors.

In April, Rowan attended a statewide competition hosted by Invent Washington. So did Richard “Ricky” Morgan, who created Super BioSoap, which is biodegradable.

The boys are in the fifth grade at Forest View Elementary. They both earned spots at the upcoming national expo in Michigan. Their teacher, Brandy Schroeder, encouraged them, they said.

Rowan wanted to solve a household problem. His mother mentioned onions.

“I was probably making dinner,” she said.

Rowan considered an item in their kitchen, a piece of stainless steel shaped like a soap bar. Cooks use the bars to remove strong smells from their hands.

The stinging compounds in onions bond to the steel, he said.

Ricky, meanwhile, has been obsessed with nature since he was little.

Soap can contribute to algae blooms, which “cause a bunch of bad stuff,” he said. “It takes up all the oxygen and kills the fish. I really like the environment, so I didn’t like that at all.”

Biodegradable soap is on the market, but his is special because it works for kitchen and medical use but also as hand soap and body wash. “It’s really bubbly,” he said.

Now, Ricky’s innovation is being distributed in Sierra Leone. A family friend with ties to the United Nations saw a post about the soap on Facebook. The friend said it would be helpful with humanitarian efforts.

Back at the Evans house on a recent night, Rowan’s mother was preparing a pasta dish that called for chopped onions.

She told her son: “Bring out the shield.”

Rikki King: 425-339-3449; rking@heraldnet.com; Twitter: @rikkiking.