Rust Grades from CarrolMcneil's blog

A Grade – A steel surface is completely covered with adhering mil scale and little if any rust

 B Grade – A steel surface starting to rust and from which the mil scale has begun to flake. laser cleaning price

 C Grade – A steel surface where mil scale is rusted or can be scraped off, but little pitting is visible to the naked eye.

 D Grade – A steel surface with rusted mil scale, significant pitting corrosion visible to the naked eye.

Steel Grade A – It is almost entirely covered with mil scale, has little rust or oxidation, and is free of pitting corrosion.

Steel Grade B – Steel exposed to the elements shows signs of surface rust, but high levels of mil scale remain.

Steel Grade C – Weather-beaten steel, it is rusting, Little or no mil scale remains and has been scraped off the surface. The pitting is clearly starting.

Steel Grade D – Steel that has been weathered for a long time. You can see pitting and rust inclusions. Extended surface oxidation leaves no mil scale.