The coming brain drain in U.S. manufacturing by Anne Fisher @FortuneMagazine November 5, 2013, 10:04 AM EDT E-mail Tweet Facebook Google Plus Linkedin Share icons FORTUNE — “Manufacturing has an image problem,” says Paul Gerbino, head of industrial-supply trade publishers ThomasNet News. “People think of it as dirty, dark, and low-paying.” That stereotype is one reason why companies that make tangible products are struggling to find candidates for about 237,000 job openings. To put that figure in perspective, it’s 89,000 more than the entire U.S. economy created in September. The shortage isn’t new — demand for factory workers has been rising sharply every year since 2005 — but it’s poised to get a whole lot worse. It all comes down to demographics. Consider: Almost 80% of the current manufacturing workforce is between the ages of 45 and 65, says a new report from ThomasNet.com. One-third are between 55 and 64 years old and starting to look toward retirement. Yet more than three-quarters of the manufacturers in the study said that fewer than 25% of their employees are under age 30, and most don’t see that changing anytime soon. As a result, the study notes, manufacturing faces a “ticking biological clock” that could derail future growth. It’s more than a little surprising, at a time when unemployment among Americans aged 18 to 29 stands at a whopping 16%. MORE: When professionals don’t practice what they preach Why the disconnect? For one thing, people in that age group are increasingly dropping out of the workforce altogether, at least for now. But even those who are looking for work “often don’t even think about manufacturing as a career, because they don’t realize that factory jobs are not what they were in the old days,” says Gerbino. “Many of these jobs involve sophisticated technology” — and they pay accordingly: Salaries can start at $50,000 or more, and climb to well over $100,00 a year for skilled, experienced engineers and technicians. Moreover, manufacturing companies have job openings beyond the factory floor: Of the 42% in ThomasNet’s poll with plans to increase headcount in 2013 if they can find enough people, 55% are looking for sales and marketing pros, and 53% need more production managers. Replacing the Boomers who’ll be stepping aside in the next few years will take “an image makeover,” says Gerbino. “Manufacturers have to get the word out to high school and college students that this can be a great career. As one of our survey respondents put it, ‘We need to create excitement about building something tangible.’” Some companies are already trying. About half of those in the ThomasNet study say they’re beginning to step up their recruiting efforts through apprenticeship and internship programs, as well as from technical schools and community colleges. ThomasNet, meanwhile, has been spurred to action by its own research. The publisher recently launched an online magazine called IMT Career Journal, which covers topics like how employers can work with local school districts to promote technical training in public high schools, and it started a manufacturing-only job board.