Parallelogram found best for glass bottles

A Japanese research team has developed a glass bottle whose lid can be easily opened even by the elderly.

The team found an optimal bottle shape through feeling and numerical evaluations. The body of the bottle has a parallelogram-shaped cross-section so that the user can tightly hold it. It has a universal design that enables elderly people, women, children, etc to easily open the lid.

The glass bottle was developed by Noriko Hashida, professor at the College of Engineering and Design, Department of Engineering and Design, Shibaura Institute of Technology, and Hakuyo Glass Co Ltd, which is based in Tokyo.

First, Hashida asked men and women in their 20s to 80s to open the lids of 15 existing glass bottle products and evaluate “the ease of opening a lid” and “the ease of holding a bottle” in the feeling valuation. As a result, she found that the ease of holding a bottle depends on how the shape of a bottle fits the shape of the user’s hand and that the ease of opening a lid increases when a bottle shape is smooth from its neck to body.

Then, Hashida measured the movements of muscles at the time of opening and closing the lids with an electromyograph and examined how a force is applied to a bottle by using clay. After that, she came up with several shapes to narrow them down to one. As a result, she found that a parallelogram is the shape of the cross-section that enables to apply a force and open the lid of a bottle most easily.

Hakuyo Glass has already filed a patent application for the bottle design. It plans to commercialize the bottle, expecting that it will be used to store food such as jam and “tsukudani” (preservable food boiled down in soy sauce).

In recent years, as the use of plastic bottles spreads, the demand for glass bottles is decreasing. Though glass bottles look more valuable, have a higher heat resistance and is more sanitary, they have a disadvantage of lids that cannot be easily opened. To eliminate this disadvantage and make the advantages of glass bottles acknowledged anew, Hakuyo Glass asked Hashida to develop a well-designed, highly-functional glass bottle.

Nikkei Technology Online