Since I never witnessed a hog killing, I could be misremembering the details he told me. I think he said they would cut a trench into the ground and somehow fill it with hot water. I guess they could have been pouring the water over...but he said they would scrape the hair off with jar lids.
Now that I think about it, Mason Jar lids are two piece. The cap part, which has a hard edge, might be used as a scrapper. It may even be better for getting at the nooks and areas hard to get at with a straight edged scrapping tool.