Inventor and engineer Mark Kennedy Bantugon poses with his invention, Pili Seal, the first sustainable aircraft sealant. (Photo courtesy of Mark Kennedy Bantugon)
In 2018, when aeronautical-engineering student Mark Kennedy Bantugon interned at the aviation-maintenance departments of Philippine Airlines and Lufthansa, he noticed the unpleasant odor of the sealants used to repair planes, prevent fuel leakage, and protect areas exposed to water or weathering. Commercial sealants are made of polysulfide, a synthetic chemical compound widely used for more than 50 years that, while effective, is toxic to humans and causes serious skin, respiratory, and eye irritations. In fact, Bantugon and his coworkers needed to wear full personal protective equipment (PPE) to handle them.
In 2019, Bantugon decided that for his senior college thesis at the Philippine State College of Aeronautics, he would invent a sustainable, nontoxic aviation sealant. He called it the Pili Seal, and it’s the first sustainable aircraft sealant of its kind.
Bantugon, who is the son of a farmer and learned how to farm at an early age, was inspired by his childhood to invent an organic sealant made from the spent resin of the pili tree, which is native to the Philippines. Resin is commonly used as an adhesive and is produced naturally, from trees, or synthetically. The natural resin from the pili tree is a gluelike substance that’s secreted by the trees and solidifies when exposed to air.
The tree’s raw resin can be distilled into two parts: an essential oil called pili oil (commonly used as an ingredient in perfumes) and the spent resin, which is typically regarded as the waste by-product of the oil-distillation process.
The Pili Seal is ingenious in its simplicity—it’s made of only two ingredients: 90 percent is pili resin, and 10 percent is a chemical hardener, used to strengthen the resin as it sets. Bantugon’s invention passed 20 different standards tests—from a flammability test to a peel-strength test—conducted by the Department of Energy in the Philippines and other Philippine government agencies. Because the Pili Seal passed a toxicity test, aviation-maintenance workers do not have to wear PPE when working with it. And unlike the commercial sealants, the Pili Seal smells fragrant, with a scent described as fennel with citrus and woody notes, because essential oils are extracted from its raw form.
Bantugon’s invention first garnered international attention in 2021 when it won the James Dyson Award’s international category.
“One of the key differentiators that stood out to the judging panel about Pili Seal,” Dyson’s senior design and development manager, Craig Douglas, explains, “was that not only was it a sustainable design with direct environmental impacts, but also social, health, and economic impacts, as we saw the potential for the design to positively benefit multiple sectors.”
Such benefits help farmers like Bantugon’s father, whose work inspired Bantugon’s invention. “His kind of work,” Bantugon says, “allowed me to establish a good and strong foundation in education, particularly in experimental-based research, which is aligned with agriculture and sustainability.” Bantugon hopes his sealant creates a steady income stream for the Philippine farming community, including his father, that farms pili trees. His ultimate goal is to make the Philippines independent of importing aviation sealants.
The sealant design was patented in April 2023, and Bantugon has been pitching it to investors from the Philippines, where he’s based, and the United States. He hopes to raise enough capital to build his own aviation-sealant-manufacturing company.
But fundraising has been a challenge, he explains, “because it’s my first time, and I don’t know the potential investors—we haven’t yet built a relationship.”
Bantugon envisions the sealant’s use beyond aircraft to cars, electronics, industrial assembly, and roofs. The last potential application is urgent, since Filipinos face escalating, strong, and destructive typhoons due to climate change that damage their roofs. For Bantugon, progress and innovation are inseparable from sustainability and problem-solving, and he hopes there will be more inventions like his.
“We need people who are willing to contribute to solving a problem and being part of a solution,” Bantugon says. “We just need to plant the right seed, not only for our lives but also for the next generation of people.”
Read more stories by Anne Lagamayo.