I have a 3 story steel exterior stairway with infill aluminum perf rail panels. We sealed the steel orig with an ext varnish that worked for over a year, but with the harsh weather we're getting this winter, I'm noticing large areas where the varnish is peeling away and the steel is exposed. The alum panels are beginning to rust as well. Window grates should be treated and painted as well.

What is the best way to clean the rust off ? It is beginning to stain the conc pad below. Any input on the best techniques would be helpful. Ie: grinding wheels on a drill ? Gels on the market that claim rust removal ? Power washing ?

Does the metal need to be treated before applying the primer ? With a very thorough job, how long can we expect this to look good and prevent further rusting??

We're looking at Duron Duraclad oil based primer and 2 coats of oil based exterior paint for metal.

I think the gels might be to expensive for a 3 story staircase, even if they do work as claimed. If there isn't too much rust, I would try using a wire brush, otherwise an angle grinder with a wire wheel or sanding disks. One trick we used to use at the steel shop I used to work at was put 2 sanding disks back to back. It made them a little stiffer (sometimes we would put a third one in the middle for extra stiffness), and you can work from both sides with it.

I've never used Duraclad Primer, but from checing Duron's website it looks like it will work fine. Just make sure everything is clean and dry before priming and painting. Putting a coat on every few years should keep everything looking good and prevent rust for a long time. Just keep an eye out for any rust spots that might need a little wire brushing and touch up a couple times a year.

Good luck,
Pete.