it's been a learning exsperence. i researched the blasting bez for about a year before we got into it. i thought i knew what was going on first i found out warpage does not come from heat. i was told walnut shells release some oil when used. not sure about that one but they know more than me. ther are so many blasting matereals it's insane. sand has been out for many years. the acrylic is softer than metal but harder than paint so it shatters the paint off without harming the metal. not sure what starblast is but it works great on rust but does not hurt the finish it's only about 10 bucks a bag. a 50 lb bag is half the size of sand.