MrWaski pisze:Co mogę zrobić żeby wyszło pięknie?

Simple and cheap way to blacken stainless:
Oil it very sparingly (any edible oil),
then heat it slowly to max. 400 °C
Repeat if needed....

... If you heat stainless with an oxy-acetylene torch (neutral flame) until it has an orange glow uniformly, then let it cool naturally it will remain black. Polishing with steel wool and metal polish enhances the finish. This is for cosmetics only. It is a very hard finish but will scratch with sharp objects. It is black about .002" into the metal.
Repeat the process again with a warm water quench and some stainless will harden. The blackening occurs because the chrome and nickel are being burned out. The remaining metal seems to be the same strength, toughness, etc.
i inne...
https://www.finishing.com/00/19.shtml

Black Oxide coatings on stainless steel are common. Type 303 has a high sulfur content that seems to interfere with the black iron oxide (Fe3O4) formation, but the rest of the 300 series can be coated to MIL-DTL-13924 [link is to free spec at Defense Logistics Agency / dla.mil] , Class 4. (I like 316 or 316L over the 304 alloy.) Remember that black oxide coating is not prescribed for corrosion protection. If you're not going to paint it, use a water displacing preservative coating such as MIL-PRF-16173 [link is to free spec at Defense Logistics Agency / dla.mil] , grade 3 or 4. The process details are found in MIL-HDBK-205A.

Get the military specs - they are free (you've already paid for them in taxes . Google "Assist Quicksearch" and put in the numeric part of the spec in the "Document Number" box.

https://www.finishing.com/17/54.shtml

Du-Lite’s black oxide is a chemical blackening process for carbon steel parts. Du-Lite provides other chemical processes to blacken stainless steel, silver solder, cast iron, brass or copper. The black oxide process actually penetrates the metal surface to provide durable protection without altering the physical dimensions or properties of the metal itself.
https://du-lite.com/about-black-oxide/? ... vOEALw_wcB