Metal can be one of the trickiest surfaces to paint. It requires special preparation and special products. If you apply paint without a thought, as if you were painting any other surface, the results may be disappointing. As professional painting contractors, every so often we tackle a job where we have to paint metal surfaces. Here are some tips to help you complete a similar project yourself, or to simply give you the knowledge of what to look for when requesting a professional estimate for painting metals.
Preparation
Like any other paint job, preparation can make or break your final results. If the metal has been previously painted, it’s important to remove any old paint for maximum adhesion. You can remove loose paint with a scraping tool. Unfortunately, with metal surfaces, you might also have to deal with rust. This can really compromise the integrity of your paint job if it is not taken care of. Heavy rust should be removed with a scraping tool or putty knife first. Then, remaining rust residue can be removed using a wire brush. The surface should be cleaned after this to remove any lingering particles from the paint or rust.
Painting: Galvanized Metal
Galvanized metal is often found on gutters and on roofs. Galvanized metal, in particular, is coated with zinc to help combat rust. Surfaces with a zinc coating require a water-based, acrylic primer to start, since oil-based coatings can interact with the zinc and cause peeling. We recommend using a DTM (direct-to-metal) product that is especially formulated for this type of work. We recommend Super Spec HP DTM by Benjamin Moore, a product we frequently work with.
Painting: Ferrous (iron-containing) Metal
Painting ferrous metals can be difficult because you are more likely to encounter rust prior to applying coatings. After completing necessary surface prep, it’s important to apply an oil-based primer to the substrate. This will not only to help prevent future corrosion, but also to create a bonding first layer between the metal and paint. For best results, apply one or two coats of a quality oil-based paint after priming.
Painting: Pre-Primed Metal
If you need to paint any pre-primed metal, it’s important to clean the surface and apply a coat of paint as soon as possible after purchasing. A month is usually an appropriate timeframe. After a month, however, the pre-primed surface may be damaged or susceptible to rust. If you paint at this point you will likely experience bubbling or peeling later on. If this does happen, you will need to clean the surface, scrape off the peeling paint and rust, sand the areas smooth, and spot prime the affected areas with a metal primer before attempting to paint again. Again, we suggest using a Direct-to-Metal paint.
Painting: Factory-Baked Enamel over Metal
This is the most common kind of metal you might encounter on a new garage door or normal door. For this type of metal, we recommend you consider leaving them as they are. The factory enamel will usually outlast a paint job as long as you keep it clean. However, painting may be a good idea if the door does not match the rest of your decor, the quality of the enamel is deteriorating, etc. If you decide to have it painted, however, expect to have it painted again every 5 to 10 years. If you are set on painting, we recommend using a Direct-to-Metal product like the one mentioned above.
And there you have it – the most common types of metal and how to paint them. Of course, it is always advised to consult a trusted professional painting contractor. When it comes to specialty coatings or trickier surfaces you want to ensure a good outcome.