"(...) Metal Finishing Techniques
Mild steel will rust upon exposure to any source of oxygen, air being the most common source. Heat causes most chemical reactions to accelerate. Therefore, if you take a piece of mild steel, heat it and do nothing else, it will rust. In order to not have your work rust, you must exclude oxygen from the metal. The amount of humidity in the air determines the kind of finish you will need. Areas having low humidity, like New Mexico, could use an oil finish for both interior and exterior work. However, areas having high humidity, like the East Coast, require stronger coatings for exterior work. - Mark Williams Phd.
Finishing Steel
Use a mixture of equal parts of liquid wax and boiled linseed oil. The wax is any liquid wax that we can find in the grocery, hardware, or auto store. We used to use liquid floor wax, but that has become unavailable in recent years (no plastic finishes please), so we have gone to the water soluble car wax that you "mix with water to wash and shine your car in one easy application."
To apply, we heat the piece just short of color and brush on. Continue applying until the liquid ceases to boil on the surface of the metal. Then quench in water and rub with a cloth. (Do not try this at home because the smell is horrendous and takes months to go away!) The finish is very durable under weather and mechanical action. Hinges, latches, dinner bells, etc. that are outside last for years before rust appears at the mechanically abused points. (Unknown Source from ARTMETAL mailing list)
For Indoor Work
Mix 60% boiled linseed oil, 40% turpentine, a dash of Japan drier . All available at your local hardware store. Make sure you remove all loose scale with rotary wire brush. Apply the mixture liberally with a brush and then wipe the excess off with a clean cloth. Re-apply as needed.
The thinning of the linseed oil allows for it to get into all the cracks and crevices. For exterior work: sand blast the piece and apply a zinc base enamel primer. Then apply a top coat. Sherwin Williams Commercial division has a graphite black premix that looks pretty good. It isn't as good as applying graphite dust while the paint is tacky, but repair touch ups are hard to match.
Final note. If you are quenching your work while it is still hot, a hard rust layer forms and is very hard to remove with wire brushing. (Enrique Vega from ARTMETAL mailing list) (...)"
