Mario you must be talking about some weak lasers. You can cut 25mm thick Hardox with or without paint. It is better with paint otherwise the steel can rust. The only difference is the speed of the cut. Also, laser cutting machines are gas assisted which blow away any gases produced and protect the cut steel surface from oxidising. I can only assume that the volcano you speak of was produced a long time ago, or someone was cutting something they should not have been. Anyway with respect to the thicknesses used to make robots I donet think even the weakest laser would have a problem cutting it, with or without paint. Anyway, if it is really troubling anyone, simply wire brush it off, after all it is only a powder paint primer anyway.