Protective coating for Carbon Steel

[RES1]

I am looking for a dip coating that would offer some corrosion protection for Carbon Steel. The coating can not add any dimensions to the part. Some type of a phosphate coating that would protect the part from indoor corrosion and handling. Something that is simple to apply

 

[phoward]

How long does it have to last?
Can it have an odor?
Does it have to be nonflammable?
Can it remain liquid to get around your non-dimension added criteria?

Does it have to dry to touch?
Why does it have to have phosphate?
Any other restrictions or open possibilities you might add?

Kerosene never dries and will give some protection as a thin coat; but it will rub off easy, be smelly, and is combustible.