Repainting metal parapet on the balcony: should you remove the old paint?
The most important part of painting is preparation.
You will want to remove all loose and flaking paint and you will want to remove all rust, which will probably involve scraping and grinding with power tools.
You will want to carefully inspect any paint that appears to be well adhered. You want to make sure that it is still stuck and that there isn't rust underneath it waiting to bubble up and pop the paint off. If you do find well adhered paint on good, solid metal, feel free to leave it. You'll probably want to give it a light sanding, just to make sure that it's got a &quot;tooth&quot; for the new paint to bite into, but if the rest of the paint is that old, it's probably pretty well worn, too.
Additionally, for any paint that is well adhered, you'll want to sand the edges to create a smooth transition from bare metal to existing paint. If you leave a sharp edge at the existing paint, you'll still see it when you apply the new paint.
When you start painting, be sure to use a good primer to ensure a good grip on the bare metal so your paint will stick longer. I don't think it would be an issue, but make sure the primer you pick will adhere well to existing paint as well as bare metal - a question to ask at the paint store.