AC 5025 SS is an alkaline material that produces black coatings on stainless and high-alloy steel without electrolysis. The appearance of the black coating depends on the surface conditions of the steel to be coated. Glossy black coatings are obtained on polished glossy surfaces, and homogeneous matte coatings are obtained on abraded or brushed surfaces. The thickness of the black oxide coating varies between 0.015 microns and 2.5 microns.