Wrong primer on garage door

Hi there,

My garage door needed repainting and I have primed bare spots with a primer for non ferrous metal which I've discovered is the wrong one as the door is made of ferrous metal!
Just wanted to ask do I need to get it all off back to the bare metal before using the correct primer? If so what would be the best way to do this?
Thanks for your help

I expect your door is not made of bare steel (very prone to rust) but of grey galvanised steel. So your primer will probably be OK. Scraping it off would damage the coating, so don't do that.

If you have any bare, rusted or blistered parts, they will need to be rubbed off and treated with a rusty steel system, which will be more work.

Thin coats of paint are better than thick, as they will be less prone to crack or craze with thermal movement.

Avoid black or dark colours which will absorb the sun's heat.

Ok thanks for your help John.