Office of Steam Forum for Model & Toy Steam Gas & Hot Air Engines

Of course. Here are some pictures of cylinders of an engine I have blackened with the Regner solution. Look at the last few pictures, with the cylinders before and after:
https://www.flickr.com/photos/28865130@N04/albums/72157622660772239

The process is easy, just place the cleaned parts into the solution (darkness varies with exposure time), then wash. However, a part of the dark surface oxide will go away with washing or handling the part, this is normal.

This is the chemical I have used: 
https://www.regner-dampftechnik.com/product-page/messingf%C3%A4rber-kaltbr%C3%BCnierer