A friend of mine was given thousands of frames of old black damaged comb by a commercial outfit. He rendered the combs in stacks of boxes with live steam. He repeatedly melted the slum and dirty wax every time reclaiming more clean wax.
He just brought me what he thinks is propolis, but is a white slightly foamy appearing slab off the bottom of his later renderings. It burns explosively. What is this? Can more wax be salvaged from it? Any experiences welcomed.