How do you make steel Blue?

Ed. note: the site is most definitely active. We have an FAQ about Black Oxide processes, and there are dozens of previous threads on the subject if you will patiently apply the search engine. Good luck with the project.

A. Bluing and black oxiding are the same thing, Andrew. If the substrate is relatively rough and matte, the topography is such that most people will call the color "black". If it is highly polished and reflective, some people will call it "blue". The oil that is applied may also enhance the reflection and the perception of the color as "blue" also, because anything reflective tends to not be called black. I have been to firearm "bluing" factories and consulted on the processes, Andew. Firearms are "blued" by polishing, followed by immersion into hot black oxide tanks, followed by oiling. Good luck.

If you go to a gunshop and ask for a re-blueing kit. This will have the rust and blue remover and sandpaper, and pick up some WD/40. This will be used as a degreaser. Also pick up sandpaper from coarse to super fine sandpaper and rubber gloves.
Once you remove the old blue and rust, place the pieces in a vice of some sort, cut up the sandpaper in thin strips and starting with the coarse hold the end of the strips inn each hand and slide across then up to remove the marks left by the sandpaper working your way to the bottom of the piece.keep doing this with a finer till the finest grit sandpaper. It's going to take at least 10 hours. You are actually polishing the steel and there should be a mirror image. Inside your kit you should find degreaser, rust and blue remover and blue and #0000 steel wool ⇦ this on eBay or Amazon [affil links] . Before putting on the blue make sure your project is free from grease. WD-40 ⇦ this on eBay or Amazon [affil links] .
Do the blueing outside or in a well vented area as the smell resembles urine.
Next would be to place the blue on a cotton ball and apply on the project very quickly wait a few minutes till it dries than rub Steel wool and watch it shine. Keep this process for about 5 times and each time polish with the steel wool...The trick is in the polishing. There are other ways but this is the inexpensive. But it also entails polishing.Good luck.

A. You can blue steel by heat tinting (heat it to 280-300 °C) or by use of chemicals (125 gm sodium thiosulphate ⇦ this on eBay or Amazon [affil links] / 45 gm lead acetate / 1 lit water, 82 °C temp., 5 minutes). Lead acetate is poison, avoid any contact with solution! Good luck!

A. Hi Tejas. While Goran has suggested two ways to add a bluish tint on steel, I'll repeat that the terms "bluing" and "black oxiding" usually refer to the same hot blackening process and the same finish. If the substrate is matte, the finish looks black because it is not reflective; but if the surface is highly polished before blackening, and oiled after blackening, many people perceive the color of the finish as "blue" rather than black and call it "bluing".

Just this past week the internet was ablaze with the picture of "The Dress" which many perceive as gold & white and others perceive as black & blue. There is a lot of subjectivity to color perception, and the general rule is that black oxiding on highly polished surfaces is what most people call "bluing".

Regards,