painting steel siding

I have steel siding on my house that is about 40 years old and as solid as the day I put it on. about 10 years ago I painted it. I used zinsser primer and top quality dutch boy exterior satin paint. the paint is in good shape, no cracking, peeling, or coming off. the problem is the paint is starting to fade from the sun. I was wondering the proper way to paint over. should I reprimer or just go over with another coat of the same paint? does the old paint need to be prepared in some manner? I am not much for painting, so the proper procedure is what I am looking for. thanks

 

Primer is for adhering paint to metal/wood/ etc.

If the paint is good then a good cleaning, scuffing down to clean all debris would be sufficient for additional paint coat!

 

Often paint will get chalky as it weathers. Not a big issue with oil base but it is an issue with latex [assuming that's what you used] You need to wash off the chalk before painting! When it isn't feasible to remove all the chalk it's best to add Flood's EmulsaBond to the first coat of latex. As stated above there shouldn't be a need for primer.

 

I did use acrylic latex. I never heard of emulsabond. I will look for it thanks.

 

I could have worded that better Both types of paint can get chalky. Oil base coatings are fairly good at penetrating the chalk to bond with the substrate but latex coatings tend to just lay on top of the chalk and will peel sooner or later. EB helps to alleviate that concern with latex paints.