Aluminum cans are increasingly being used for canned coffee in Japan, grabbing market share from steel, the conventional material for containers of the ubiquitous beverage.

According to data from the Japan Soft Drink Association, the market share of steel cans fell to 45.7 percent in 2014, while that of aluminum cans increased to 22.3 percent. Plastic bottles accounted for 20.3 percent.

In the face of growing competition from aluminum cans, steel makers and can manufacturers are working hard to reduce the weight of their products.

As aluminum is weaker than steel, the inner pressure of an aluminum can needs to be higher if it is to be used as a beverage container. But high inner pressure makes it difficult to carry out checks for bacteria inside the container.

Therefore, the soft drink industry long avoided using aluminum cans for coffee with milk, due to the possibility of bacteria developing inside the cans.

But seeking the benefit of lower transportation costs for aluminum, which is one-third the weight of steel, beverage makers have gradually adopted aluminum cans shaped like bottles for black coffee products since the middle of the 2000s.

In August last year, the soft drink industry modified its rules on materials used for beverage cans, lifting a ban on aluminum cans for coffee with milk, after improvements in the production process and better quality control made it possible to stop bacteria from getting into beverage cans.

Following the change, Coca-Cola (Japan) Co. switched from steel to aluminum cans for 23 of some 40 products of its mainstay Georgia coffee line. Kirin Beverage Co. adopted aluminum cans for four products.

Aluminum manufacturers are excited about the rising demand.

Showa Denko K.K. has added a production facility at a subsidiary plant. “We hope a further shift (in demand from steel cans),” an official said.

For their part, steel makers and can manufacturers are racking their brains for ways to make cans thinner yet strong enough for use as beverage containers, thereby cutting transportation costs. Taking advantage of steel being more workable than aluminum, the manufacturers exercised ingenuity in the shape of a steel can.

A steel can to hold 190 ml currently weighs a little less than 30 grams, down 20 percent from 10 years ago and coming closer to some 10 grams for a comparable aluminum can. Steel can manufacturers believe that cutting the weight by an additional 20 percent could make a steel can comparable to, or even better than, an aluminum can in terms of cost competitiveness.

Beverage makers are closely watching the competition between manufacturers of materials for coffee drink cans. “We are looking at both steel cans and aluminum cans as options,” an official of Coca-Cola (Japan) said.