Coloring steel

Hubert Carr's "metal black" works well. Just brush it on and wait.

Blueing and Parkerizing are both very durable finishes.

Black oxide is a commercial process.

http://www.clevelandblackoxide.com/

Browning and blueing already mentioned.

If you're doing it yourself, any of the gunsmithing purveyors will sell you kits.

http://www.birchwoodcasey.com/

milo

Black oxide

Don't forget about electro, and electroless plating.

I read about a high end treatment on sniper central website. can't remember the name but the gun builders and customizers have some surprisingly effective products.

Hi carcu

If you decide to try a bluing process as mentioned earlier, try This stuff:

http://www.brownells.com/aspx/NS/store/ProductDetail.aspx?p=1072&title=OXPHO-BLUE~

I used this for years on customer's guns in my shop back in my smithing days. It's the Best cold blue I've ever used! Real easy to work with and creates a nice finish that is very resistant to harmful rust.

Not real cheap but a little goes a long way.

uh.... try paint

they are plenty of electroplating finish and color avaible for steel u can try to find a plating shop around your area