There are a few different methods of doing this depending on how good of a job you want to do how much time and energy you have and how large of an area you are doing.
How to repaint metal siding.
It is imperative the enamel finish itself not be removed during this process.
Cleaning of the surface can be done by hand washing with warm soapy water or with the use of a high pressure washer 2500 psi minimum.
First i washed down each wall with a garden hose to remove the loose dust and then filled the detergent tank with krud kutter pressure washer concentrate specified for house siding.
Step 4 letting dry and cleaning equipment.
That is how you can get the paint to adhere to steel siding.
Step 3 paint.
The first step includes cleaning.
Restore the original color and finish instead.
I would use the red rust oleum primer the oil based primer and i would let it thoroughly dry after you knock off all the loose paint and sand it and make sure the surface is ready to accept it.
After the building has been properly prepared it must be immediately coated with a direct to metal epoxy primer.
Wash the steel siding with trisodium phosphate tsp and use a pressure washer.
Set the washer to low then direct the water flow over the panels working along each panel length to remove any dirt or debris.
Step 2 tackle rust.
Step 1 cleaning the metal siding.
When applying a detergent with a pressure washer you have to lower the pressure and use the right nozzle a low pressure tip.
Step 5 applying.
Begin by thoroughly cleaning your siding of all loose dirt chalk and other contaminants.
Metal siding is often subjected to extreme moisture that will make it rust or accumulate a thin layer of oil.
How to paint metal siding.
There is a great alternative to re painting your metal siding.
Step 2 protecting other areas.
As with all exterior painting projects proper surface preparation is the key to restoring your metal siding.
You can easily restore the original color and finish to look new again without all the problems of painting.
Place a low pressure tip onto the washer.
If you are striping a small area then you can do very well with a bucket of water that has some bleach and tsp in it.
How to paint steel siding.
Step 1 clean the steel siding.
Wait two hours for the siding panels to dry.
Step 3 applying primer.
If poor adhesion is observed the surface must be roughed up by sanding 400 mesh recommended or power washing.