Japan team develops ‘eco-fireworks’ with water-soluble shells to cut debris

TOKYO – A Japanese fireworks manufacturer and a university professor have jointly developed more environmentally friendly fireworks with water-soluble shell casings that naturally dissolve after use, in hopes of reducing the impact of fallen debris after displays.A fireworks ball consists of gunpowder layers inside the outer shell, which shatters upon explosion and falls to the ground. While debris from conventional casings, typically made of kraft paper, takes half a year to decompose, the new shells incorporating water-soluble resin can dissolve in as little as one day.Hiroyuki Kakinoki, president of Kakinoki Fireworks Industry based in western Japan’s Shiga prefecture, said: “We want to accelerate the decomposition speed and reduce the environmental burden.”With the newly developed shells, debris from a standard medium-sized aerial firework of around 12cm in diameter can dissolve by the following day under the right conditions, according to the team involving Kakinoki Fireworks and Ryukoku University professor Takahiko Nakaoki.The new shells use a water-soluble resin commonly applied to agricultural seeds and soil improvers.The biodegradable material is considered harmless even if consumed by living organisms, with no adverse impact on the environment.When exposed to moisture, the new shell becomes soft like heated caramel and can dissolve almost completely within a day in areas with flowing water, such as rivers.In Japan, many fireworks festivals are held over large rivers, lakes, or at sea.Although kraft paper is still used to keep moisture away from the shell, paper consumption can be reduced from about two A3 sheets for a standard aerial firework to just about one sheet.During the development process, one of the challenges was the resin’s stickiness, which caused it to adhere to the machine making the shells. By adjusting the amount of release agents, the team succeeded in manufacturing shells that could be peeled off cleanly.Kakinoki Fireworks has been working on developing more environmentally friendly fireworks for about 25 years, including efforts to reduce remnants. It previously tried to make shells using a different biodegradable resin but abandoned the attempt after facing problems such as the generation of microplastics.In 2018, the company was introduced to Nakaoki, an expert in polymer science, and the two sides began the joint development project, which ultimately led to the completion of the new shell. KYODO NEWS