PORTLAND, Maine — Maine’s recreational pot business is ready for a boom, but is only experiencing a slow burn. There’s plenty of retail consumer demand but the licensing process is slow, making raw materials scarce. That, in turn, slows down the manufacturing pipeline and makes for empty shelves in retail stores. “It’s supply and demand at its worst,” said Dave Page, owner of Coastal Cannabis in Damariscotta. Page was ready to open his store on Oct.