A small crowd at the Clark County Antique & Collectible Show gathered around Charles Tovar as he used a paintbrush to swirl clear liquid onto an old oil painting.The Forest Grove, Ore., art restorer was removing dirt and even insect poop from the work of art. Most of the paintings he restores from the late 1800s or early 1900s, however, are covered in something else, too.“Coal dust,” he said. Many homes during that era used coal-burning stoves, which over time blanketed household items, including art, with a dingy coating.Those darkened paintings are less attractive to modern-day collectors, meaning Tovar is able to grab them up, restore them and resell them. He had restored paintings, drawings and sculptures on display Sunday at the collectibles show, and they were priced from a couple of hundred dollars to thousands of dollars.Organizers of the annual antique and collectibles show said the event offered more fine art and higher-end items than usual among its 250 booths this year. It was the 12th year for the show, which was at the Clark County Event Center at the Fairgrounds over the weekend.