Engraving mild steel

I bought some new mild steel sheet yesterday. It was 1.5mm thick. It was much newer than the other steel I got. It sanded clean very easily and was not pitted with rust. I engraved this with a 3mm slot drill, a 1mm slot drill and my engraving tool; nominally 27.5 degrees half angle, 0.1mm cutting diameter at the tip.

I was pleased with the result, although I had to tidy it up with my pen-knife and sand and polish it to get shiny ridge tops. Also, the fine detail pass at 0.05mm depth left a step on the ridges.