Hello - I am planning to repaint my metal roof to give my garage a better appearance. As you can see in the pictures there is some minor surface rust covered on a large area of the roof. The material appears to be galvanized steel (attracts magnets). My plan was to (in this order) wire brush the roof first, apply phosphoric acid for any residual rust not removed from wire brushing, then apply a TSP detergent to clean the surface, followed by pressure washing the roof, applying a rust inhibitive primer, then an acrylic exterior paint. Any changes or additions to this process you would recommend? I have seen acrylic paint products labeled as "Direct to Metal (DTM)" that claim they do not require primer application beforehand, however the information I have seen thus far suggests always using a primer even with this type of paint.
The next thing I am struggling with is how to apply the primer and paint. The roof has the channeled profile so I would need to find a special roller that matches the roof profile in order to apply by roller. The other method I considered was renting an airless sprayer, however I must admit I do not really have experience with these so I'm not sure this would be a good situation to learn this skill. Appreciate any feedback, thanks!
The next thing I am struggling with is how to apply the primer and paint. The roof has the channeled profile so I would need to find a special roller that matches the roof profile in order to apply by roller. The other method I considered was renting an airless sprayer, however I must admit I do not really have experience with these so I'm not sure this would be a good situation to learn this skill. Appreciate any feedback, thanks!