How to prepare and paint metal fences and gates
As you can see in the picture to the right…this fence has seen better days! The underlying metal is raw steel whose main component is iron. Once the raw metal is exposed, it immediately starts to react and turns to iron oxide rust, which in time will eat through the surface creating pits and holes If you are considering a fence like this , be sure to request a heavy galvanizing treatment before painting….this has to be done in a shop that specializes in galvanizing. Galvanizing is a process of applying zinc to the steel….you will get many more years out of your metal if it is galvanized.
How to treat red rusted iron fences and gates
The key here is to remove all loose/flaky rust by wire brush/wire wheel on a grinder and/or a abrasive grinding wheel. And do not forget to clean and degloss the remaining sound coating. To get good adhesion of topcoats, the surfaces must be chalk free and deglossed.
If your project is a gate that is removable, the absolute best system is to remove the gate, take to a sandblaster for blast cleaning to bright metal and then have it either powdercoated if you live in a dry area or have a marine primer/finish shop applied.
Prep tools needed:
- Grinder and abrasive wheel/wire wheel
- Safety glasses and gloves plus earplugs.
- Sandpaper, sanding block, 3M abrasive pad.
- For a bulletproof job the next step is to pre-prime all rust with a very thin penetrating two part epoxy primer that will bind the surfaces at a molecular level; follow this with a mastic (very thick) two part epoxy to create a thick barrier between the metal and the elements; follow this with a two part polyurethane topcoat. This system is the most durable and also the most time consuming.
- More commonly, folks choose to wire brush/abrade to a tightly adhering rust surfaces; then apply a rust converter primer such as Rust Destroyer…a product that contains Phosphoric acid to transform the rust as well as provide a thick barrier coat. This product will take a few days to dry as it is not catalyzed. Follow with one or two topcoats of a true oil enamel (thinned with paint thinner). Look for a product that says “silicone alkyd”
- As best you can, keep irrigation water from hitting the fence and keep dirt from burying the base of the fence…these are usually the culprits that cause the most damage to iron fences
Tools for priming and painting?
- Because there is usually a lot of fence, the best way to apply your primer and paint is by using what we call a 7″ small diameter “weenie” roller and a two gallon bucket with a metal washboard grid. Your local paint store will know what to give you if you ask for the above. This roller system allows you to get at all the surfaces from one side of the fence and critically the small diameter roller will allow you to load primer and paint on the underside of the fence which usually is hard to reach and has a “U” shaped channel that must be fully coated….as this is where a lot of rust starts