How to achieve black mirror finish on stainless steel

Q. I have a flat discs, 100mm diameter, of thin (0.3mm) stainless steel sheet, perforated with 0.5mm holes. It's annealed 316 steel.

I want to make one side black (preferably matte), and the other bright and shiny. Whatever finish I use, it mustn't block the holes (although I don't mind if they are reduced in size a little).

The discs will be in vacuum after finishing, so corrosion isn't a problem.

I was wondering about giving them a wash of silver, then putting them on a flat surface and passing hydrogen sulfide over them, to blacken only one surface. But I'm unclear about how bright a silver wash would be.

Does this make sense? Would I have to give a copper wash first?

Or maybe there's a better way.

Thanks,

A. Martin, you can simply use diluted muriatic acid [affil links] applied by brush or sponge. Birchwood Technologies [a finishing.com supporting advertiser] also makes a blackening patina for steel to achieve similar results. Good luck Barry Feinman BarrysRestoreItAll Carlsbad, California A. Oil one side very, very sparingly, then heat it to 300-400 °C (slowly). Any edible oil or fat can be used but linseed oil [affil links] is best.Repeat if needs.Hope it helps and good luck! Goran Budija - Cerovski vrh Croatia A. Stainless steel is probably the most difficult metal to colour by the usual oxide or sulfide treatments. The simple answer is why not paint it? Shiny side down on a piece of paper and use a high temperature spray paint as used on car silencers (try Halfords) An even simpler answer is to coat it with carbon. Simply hold it in a candle flame (high up in the yellow part). If you don't like it wipe it off. Geoff Smith Hampshire, England

Q. Hello There,

I am an art student currently working on a large metal sculpture. So far, it is a large stainless steel rectangular cube about 7 feet tall. It was fashioned out of extra scrap metal from out art department. I've run into a few problems. The steel sheets have a factory coating on them that became very mirror-like after experimenting with sanding. I wanted to achieve this look uniformly around the entire piece, but after grinding down my welds I have already taken off this great black finish around the edges.

I figured I'd have to sandblast the entire thing and re-coat with a metal patina. I ordered some Black Magic from Sculpt Noveau. I am deathly afraid that I won't be able to achieve the mirror effect from the factory coating. This project will be placed outside and will need to withstand the elements. Any help would be greatly appreciated!