A booming business based on the nationwide popularity of craft beer has left the humble beer can in short supply.

The squeeze is specifically in small orders of 16-ounce cans, used by several Maine brewers who have reported supply problems, said Sean Sullivan, executive director of the Maine Brewers’ Guild.

“There’s just too many breweries,” Sullivan said of the national explosion of beer makers. He said most Maine brewers have enough cans on hand to avoid a panic, but managers are scrambling to find new suppliers before they exhaust their inventories.

Most beer comes in bottles, but a segment of the craft beer industry has taken a decided turn toward using 16-ounce cans. The size differentiates it from mass-produced 12-ounce beer, and cans preserve quality since sunlight can degrade beer. Also, the target market for craft brews – hipster, outdoorsy types – can more easily transport canned beer in backpacks or take them where glass bottles are forbidden, including most parks.

All of that has created a growing demand for craft beers in 16-ounce cans and strained the segment’s primary supplier, Pennsylvania-based Crown Holdings. Normally, beer can suppliers deliver a minimum order of 155,000 cans – the payload of a conventional 18-wheeler. But Crown, a metal can manufacturer, developed a niche business catering to those small brewers who only needed half-truck orders.

A few months ago, word started trickling out that Crown would no longer offer half-truck orders, and was dropping some customers entirely – even if they ordered full truckloads.

That’s what happened to Portland’s Rising Tide, owner Heather Sanborn said.

“We were shocked by the news,” said Sanborn, adding that her brewery had purchased three full truckloads of cans from Crown in 2015. “I spent probably four very sleepless nights, literally, wondering if we were going to be able to continue with our most popular brand,” the Maine Island Trail Ale.

Sanborn has found a new supplier, and aside from some additional art costs to rebuild the graphic design of the cans, there was no significant financial hit. Some sales were lost when Crown delayed the delivery on the cans for Rising Tide’s winter brew, dropping them off the first week of November instead of early October, as expected.

“We lost the sales we would have had for those weeks,” she said. “But for us, knock on wood, it’s just been a lot of stress and a lot of scrambling.”

Bart Watson, chief economist for the Brewers Association, said the situation is affecting brewers nationwide.

The association’s members are reporting a range of issues with Crown, which has neither put out a public statement on the situation nor offered an explanation to the Brewers Association. Crown did not return calls for comment on Monday.

Some brewers are reporting delivery delays and some have been notified that they must buy a full truck at a time, Watson said. Others, like Rising Tide, report being dropped entirely.

The shift by Crown isn’t surprising, Watson said. There’s not a lot of money for major can manufacturers in the small market for 16-ounce, preprinted cans.

“To quickly retool and rebuild for a change in the industry is challenging for these larger manufacturers,” he said. “They’re built for big, long runs.”

Some brewers have adjusted by finding new suppliers, but others switched to ordering plain 16-ounce cans and putting their own shrink-wrap labels on them.

Watson said the manufacturers are trying to keep up with a booming market, adding that beer isn’t even the biggest player in 16-ounce cans.

“Products like energy drinks do a lot more volume in that package, which may be one reason for some of the disruptions as well,” he said.

‘SMALL PLAYER IN A SMALL MARKET’

In the late 1970s, there were fewer than 50 brewing companies in the United States. Today there are 4,000.

Craft brewers, who make less than 6 million barrels a year, make up only 3 percent of U.S. beer sales. Within that 3 percent, only about 10 percent of craft brewers use cans, and those that use the 16-ounce size are “a very small minority” within that, Watson said.

And for brewers who use 16-ounce cans, they may have multiple small-batch varieties, all with different labels that require manufacturing different preprinted cans.

“It’s a small player in a small market,” Watson said.

Mainers, however, can be excused for thinking craft breweries play a bigger role in the beer market. Maine ranks sixth nationwide for breweries per capita, and seventh nationwide for per capita beer production, Watson said.

“(Maine) certainly punches above its weight,” Watson said.

Baxter Brewing Co., which was the first regional brewery to exclusively use cans, said it wasn’t affected by the situation because it has a different supplier, Ball Corp.

Sullivan, the director of the state’s brewers’ guild, said most Maine brewers still use bottles. It’s easier, less expensive, and a switch to canning means a six-figure investment in a canning line.

But craft brewers, and their customers, like cans, Sullivan said.

“Craft brewing as an industry is definitely shifting to cans,” he said. “They’re easier to transport, more environmentally sound, in theory, and people appreciate them.”

The supply disruption has hit several Maine brewers who use the 16-ounce cans, but none was affected immediately because Crown honored existing contracts, he said. But there is concern it could turn into a problem in 2016.

“It’s not as if there is anyone left with beer in the tank that they had to dump,” he said. “It’s a long-term impact.”

Watson agreed, considering the steady growth in the craft beer industry.

“We’re not increasing the number of can manufacturers in this country,” he said. “This may not be the last time we hear about this issue.”

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