As temperatures moderate, everyone changes their focus to the outdoors and thinks about backyard entertaining, sprucing up the patio or deck–or just lounging on the lawn. Often that means doing something about the tired-looking, corrosion-prone patio furniture. And while a new paint job would do wonders for the substrate–as well as the appearance of these outdoor pieces–the prospect of prepping, priming and painting detailed ironwork or leggy, spindled pieces is daunting. To help with this not-so-familiar project, here are some recommendations and tips:
1. Assess the substrate: Metal furniture, structures and accessories are typically iron (steel) Galvanized iron or aluminum (which is easy to identify because it’s easy to lift). Steel can oxidize (rust) and peel. Galvanized steel will rust if the zinc layer on top of the steel is scratched. The zinc layer is soft and can be easily scratched with a nail or screwdriver. Aluminum, which is usually powder coated, can just peel (almost inevitable if exposed to a lot of UV).
2. Analyze the finish: First test by wiping the surface with a rag dipped in xylene. If the film softens, blisters or crinkles, you have an alkyd finish. If there’s no effect, it’s a harder finish such as epoxy, urethane or a powder coat. To check for a possible water-base coating, wipe with denatured alcohol; the color will transfer to the rag if it’s latex or acrylic.
3. Plan the approach: When it comes to metal items, it’s best to stick with alkyd primers and finishes. They dry harder and are more abrasion resistant than water-based finishes. The ideal application method–for the coating, as well as the irregular shape surfaces of outdoor furniture–is spray, specifically, HVLP. It’s easier and yields better results than brush-on. An alternative would be a fine mohair roller (short nap); then tipping out with a brush.
4. Prep the surfaces: Start with a simple (but thorough) washing with a bit of detergent and water; then rinse. Sand all surfaces to give it tooth (micro grooves for the new finish to grab). In rusted areas, sand all the way down to the clean (rust-free) steel. For aluminum as well as steel, remove all loose finishes and feather edges (to the point where you can’t flick an edge when scraping along with you fingernail). If you choose to go down to bare iron/steel by sandblasting, it’s essential to apply primer immediately to stop corrosion in its tracks.
5. Apply the primer: Spot prime bare iron/steel using alkyd metal primer such as Benjamin Moore Super Spec HP P06, Alkyd Metal Primer or P07 Universal Metal Primer, which dries faster (a consideration when applying by spray). On galvanized surfaces, use Super Spec HP P04 Acrylic Metal Primer. Bare aluminum can be primed with P04. You do not need to prime areas that still have a finish; just scuff-sand for better adhesion.
6. Finish with a top coat: Commercial alkyd coatings, such as P22, P24 and P26 are good choices. If you need to use an acrylic finish, P28 or P29 would work well. These high performance products may not be on the shelf at all dealers. Some consumer-level options are C163 (Ironclad) and C133 (Impervo), both of which are alkyd materials.