The tubing comes lightly oiled to prevent flash-rusting during storage and shipping. Clean any surfaces to be welded with chlorine-free brake cleaner and a lint-free rag and wire brush. Most of our tubing was laser-cut with clean ends, but a couple had been mechanically notched. We cleaned up any burrs with a half-round file. Cleaning each tube end inside and out before beginning will make the assembly flow more smoothly and help ensure clean, strong welds.