Corrosion-Sensitive Environment

Q. I have some fencing around my swimming pool that has corroded badly over the years. It was made with steel and there is a lot of visible rust on the rails and vertical pickets. I am considering the options; have a professional painter come in and clean, repair and repaint the fence; or have the fence replaced with one better equipped to handle the harsh environment around the pool. What would you do if you were me?

A. First, let’s address the issue of painted steel fence around a swimming pool. Probably a bad idea unless it has several layers and zinc phosphate on the steel. Water, heat, chlorine, sun, what could go wrong? The fencing options around a pool should put painted steel near the bottom. Galvanized fencing is a pretty good option. The zinc coating is a sacrificial barrier to the elements and it will work pretty well. It will show signs of age and become dull-looking and may break out in some areas over time but it can work. If you want color or the textured look of a coated surface, you should strongly consider aluminum. The aluminum substrate will not show the red rust common with iron. 

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The next critical aspect of the coated metal is the pretreatment used. Aluminum can be treated with several chrome or non-chrome conversion coatings to protect the substrate and create a good surface for bonding. A good conversion coating will add a lot to the necessary corrosion protection. 

With a good pretreatment in place, the next issue is what powder layers to use. You could use one coat of polyester powder. The polyester will protect against sunlight but one layer is still vulnerable to moisture penetration and breakdown of the coating. A second layer is definitely recommended. It protects the sharper edges much better and limits moisture from penetrating to the interior substrate. A powder primer should be seriously considered. The primer enhances the corrosion resistance significantly. 

So what would I do if it were my fence? If you have it repainted I suggest you keep the invoice and phone number of the painter for future reference. It will not be the last time you need their services. Get used to a budget to repair the fence every few years. I would seriously consider replacement with aluminum that has been properly treated, primed and topcoated. Be sure the supplier understands the environment and provides protection for friction points or fittings. Also, the design of the fence matters. It cannot have exposed metal or areas that will trap and hold moisture. It should avoid sharp edges. It will be a big bill when you do it but the look will last and maintenance will be much lower over time. 

Originally published in the January 2017 issue.