[RichardH]

I had a project recently that was cut from cold rolled bar stock before I welded it up. I was surprised to be fighting contamination in the weld, as I'd cleaned off the oil and wiped it down with acetone. Turned out, it seemed to have a thin layer of mill scale that had to be wheeled off, despite being shiny.

I don't usually use cold rolled, but I thought the CR process caused it not to have mill scale, which is why it's kept oiled. Am I wrong here, or what else might this have been?

Thanks,
Richard

[zank]

Yes, cold-rolled generally has scale that should be removed prior to TIG welding. If you just brush it, it does shine up. But you are not getting down to bare metal.