Adam Minter, Bloomsbury, 299 pages, $28. Adam Minter’s “Secondhand: Travels in the New Global Garage Sale” is a fascinating account of what happens to that sweater you bag for Goodwill or the totaled car your insurance company writes off. It is eye-opening — and even surprisingly hopeful. Journalist Minter, who hails from two generations of junkyard owners, makes his living from writing about reuse. His last book, “Junkyard Planet: Travels in the Billion-Dollar Trash Trade,” chronicled the fate of waste and international recycling. He carries on the work in “Secondhand” by following the merchandise — and the money — from objects discarded in Minneapolis or Tucson, Ariz., to ports as far-flung as Malaysia and Benin. The rag-and-bone trade is now a huge, complex international business. He begins with the proliferating companies, like Empty the Nest, that help facilitate poignant clean-outs of people’s homes when they are ready to downsize. Then it’s on to a Goodwill in Tucson, where he tracks a never-ending tide of objects. As he documents, by no means do most things donated to a Goodwill sell. Next stop for the remaining flood of stuff is Goodwill Outlet Centers, where they are sold by the pound to specialists, many of whom will cross the border to resell in Mexico. Other tons go to Pakistan or Africa. What doesn’t make the cut there is often shipped back to the U.S. to be broken down into rags — who knew that rags are such big business? Minter is no poet. His prose is statistic-rich and straightforward. He’s at his best in the chapters discussing the ecological impact of waste as it relates to product durability, and encouraging companies to be more transparent about planned obsolescence.