Etching Steel

Question: I am looking at using media blasting to identify/mark items made from stainless steel sheet using stencils to allow shielding of areas I don't want to blast. The stainless steel (used in a food factory) is highly polished. I was hoping media blasting would give a different enough surface finish to make the marking easily visible but what media would be best to achieve this?

Also, would a direct pressure or suction system media blasting cabinet be best? The factory air system produces up to 90 psi and supplied more than enough air to run lots of machinery.

Response: You can use either Aluminum Oxide or Glass Bead to create the marking you described. Aluminum Oxide will produce an etched finish with finer grit sizes producing a smoother, lighter etch. Glass Bead will produce a smooth, peened finish with finer grades producing a more uniform, matte finish while coarser grades will leave a brighter finish.

Either a suction system or direct pressure blast system could be used. The pressure system will typically shorten the cycle time, produce a more uniform surface finish and allow for more media re-use since you can blast at lower pressures.