Rust on metal railings is caused by a number of conditions. Most common is wear and tear on the paint protecting the metal from rusting. As paint ages and dries out, it cracks, letting moisture attack the metal to start the rusting process. Scratches and nicks in the paint will create the same situation. Metal rusts anytime it is not protected from moisture.
When railings are constructed, the metal components are ground or brushed to remove rust, welded together and then painted. If there is a delay in the final painting, the bare Industrial Paint metal may begin to rust. The rust is not visible and is hidden in the pores of the metal. The metal is then painted. After the railing is installed, it may start showing rust through the paint, eventually forcing off chips of paint. This could happen within a few months of being installed.
To stop the rust and restore the railing to a new rust free condition, the rust must be stopped or completely removed. In the past, this required removing the rust and paint, then priming and repainting the surface. This is a very time consuming and expensive process because of the many hours required to grind off the rust and paint.
Thankfully, there are now non-toxic, latex-based products that allow you to stop the rust without the time and expense of grinding off rust and paint. These can be painted over the rusty surface to neutralize the rust and prime the entire surface. A good topcoat of paint will restore the railing to a new condition and give long-term protection against rust.
The easiest way to apply these products is to use a paint mitt (available in paint stores) to spread them over the metal. This is much faster than using a paintbrush. When finished treating the surface, wash the mitt with soap and water to clean it for reuse.
The surface will be dry in 20 to 30 minutes. After 24 hours you can top coat with any kind of paint. As long as the topcoat is maintained and not allowed to crack and breakdown, you will not have to deal with rust on your railing again!