AC 5025 SS is an alkaline material that forms black coatings electroless on stainless and high alloy steel. 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, while homogeneous matte coatings are obtained on etched or brushed surfaces. The thickness of the black oxide coating varies between 0.015 microns and 2.5 microns.