I've never built a UDS before and I don't know what I'm doing. Now that we have that out of the way, I ordered an "unlined" drum from a local supplier and when it arrived it had a slight pinkish lining on about 40% of the drum. I tried burning it and then grinding it out and, while the burning and grinding took most of the pink build-up there is still some left even in the spots that I ground. I contacted the manufacturer and they assured me that their remanufactured drums are all unlined and processed with an incinerator as well as being media blasted. So my question for all of you is this: Is this an actual "liner" or is it just some pinkish rust? Here's a picture of the drum in its current state. There was also some exterior paint that seems to have made itself interior paint.