You could clean it very well to remove all oil and hit it with cold gun blue then re-oil. A phospate chemical like used in boilers could also give a dark finish.

Dan D.

 

there are some rubbed bronze stains out there that would work as well.

http://www.sculpt.com/catalog_98/patina/Stains_Oils.htm

As Dan mentioned, it will need to be a chemical to get it to stain.

 

Ospho. NAPA used to have it > Does NAPA still exist ?
[video=youtube;MVxaWeseToo]https://www.youtube.com/watch?v=MVxaWeseToo[/video]

 

NAPA still exhists Burpee.

Brooklyn, have you looked into blueing like as in gun blueing?

 

The Ospho is the exact same reaction as liquid cold blue. Just a slightly different makeup.
Like anything "gun", bend over .Pho is for phosphoric acid, used in both products.After a coarse blast on a shotgun barrel the Ospho actually "blues" better and lasts as well as Oxpho.
http://www.brownells.com/gunsmith-t...oloring/metal-bluing/liquid-cold-bluing-chemicals/oxpho-blue-reg--prod1072.aspx

 

Load it in the mini van and take the kids to lunch.....it's bound to get stained.

 

Water it down al let it rust some. Next time leave the mill scale on it

 

Sand blast it, it wont be shiny anymore, at least.

 

Using the table will fix your problem

 

vinegar, or ferric chloride