03-12-2012, 02:29 PM
If it's simply structural steel shapes (I-beams, H-columns, etc.) it would likely be unpainted. Grey, blue/grey, black would be common, and, as MountainMan notes, likely with some signs of rust. This could range from just a hint here and there, to totally rust-covered - some grades of steel oxidise very rapidly, then that surface coating protects against further action.
For pre-assembled construction steel, such as roof or floor trusses, these are usually painted at the assembly plant, either in primer (probably red lead in the '50s) or in that company's "stock" paint colour. The customer could probably request a particular colour, too, depending on where it was going to be used. Of course, when a roof is a couple hundred feet wide, the trusses would likely be assembled on-site and probably painted before installation.
Most of the mills in the steel plant where I worked had the structural steel painted grey, the steel floors non-slip red, and the outside of the buildings (usually corrugated siding) in various colours or unpainted galvanised.
Wayne
For pre-assembled construction steel, such as roof or floor trusses, these are usually painted at the assembly plant, either in primer (probably red lead in the '50s) or in that company's "stock" paint colour. The customer could probably request a particular colour, too, depending on where it was going to be used. Of course, when a roof is a couple hundred feet wide, the trusses would likely be assembled on-site and probably painted before installation.
Most of the mills in the steel plant where I worked had the structural steel painted grey, the steel floors non-slip red, and the outside of the buildings (usually corrugated siding) in various colours or unpainted galvanised.
Wayne