How do you prevent your wrought iron railing/gate/fence/flowerbox from rusting? We often get asked by fabricators and homeowners alike whether an architectural metalwork project should go through the galvanizing process to prevent rust. It does add upfront project cost, a logistical step that must be outsourced, and weight to the piece. So like most things, the answer is that “it depends.” In this article, we’ll review the benefits and considerations of galvanization, specifically hot dipped galvanization. Whether you are fabricating or making a purchase decision, it’s important to evaluate this all-important finishing option that can extend the longevity of your project.
What is galvanized steel?
First things first, what does “galvanized” mean? We use “galvanized” to refer to hot dipped galvanized and it has been around for over 150 years. After fabrication is complete, a steel (wrought iron) railing, fence, or gate, is brought to a local galvanizer. There, it goes through a thorough, multi-step cleaning process before an operator uses a crane to dip the piece into a massive bath of molten zinc. The zinc coats the entire piece, including any interior surfaces such as tubes and channels, and hard-to-reach crevices created by ornamental accents. This durable zinc layer adheres to the metal and protects the steel, creating a superior resistance to corrosion. By protecting the steel from the elements, the chemical reaction that creates rust cannot occur. Our friends at the American Galvanizers Association have a collection of helpful resources if you want to dig into the details.
Benefits of galvanizing for fabricated architectural and ornamental metalwork
In general, we recommend hot dipped galvanizing for any exterior metalwork project that uses steel or cast iron components. Based on our decades of fabrication experience in both residential and commercial settings, this additional finishing step offers a superior post-installation experience that extends the aesthetic beauty of the piece, and nearly eliminates regular maintenance requirements. An owner of a galvanized piece can expect to enjoy the following benefits for many years:
- Minimal maintenance
- Superior corrosion and rust resistance, even near salt water environments
- The only option that protects difficult-to-reach surfaces on ornamental elements like rings, scrolls, and baskets
- Virtually no rust bleed onto the ground, concrete, wall, or expensive masonry
- Can be re-galvanized for generations to come
Fabrication details to consider when choosing to galvanize
- Tubes and fully-enclosed caprail and channel assemblies require small, drilled holes to allow the molten zinc to flow throughout. Consult with your local galvanizer.
- May require using stronger, bigger, thicker materials to withstand the heat of the zinc bath. For example, use ¼” or thicker solid plates to prevent warping when using as a bottom plate in a gate fabrication (see below gate photo).
- Steel and cast iron are galvanized best at different temperatures. We recommend galvanizing them separately, then mechanically fasten.
- Ensure high-quality, professional welds throughout.
- Some preparation work and/or job minimums may be required by your local galvanizer.
- Size of a single section may be limited by the zinc bath size of your local galvanizer. This maximum can range from 10 feet up to 40 feet. In general, the bigger the section, the stronger it needs to be to prevent warping. Consider metalizing as an alternative (see below).
- Use stainless steel fasteners throughout.
- Some post-galvanized finishing should be expected. Utilize a used sanding disk to avoid damage to the zinc layer.
- We do not recommend hot dipped galvanizing for entry doors, or wherever an ultra-smooth surface finish is desirable.
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Frequently Asked Questions
Architectural and ornamental metalwork that is hot dipped galvanized can expect a long, virtually maintenance-free lifetime. In most non-industrial environments, metalwork will not require corrosion maintenance for at least 30 years, depending on the thickness of the zinc layer. In comparison, non-galvanized exterior metalwork requires attention every one to two years, regardless of paint or powder coat finish. If significant corrosion develops, the metalwork can be re-galvanized.
Yes, galvanized steel and wrought iron can be painted or powder coated. However, do not use oil-based paints. Specialized paints for use on galvanized steel are available, with most products coming from the popularity and ubiquity of galvanization in Europe for exterior applications.
While we believe hot dipped galvanizing is the superior process for protecting your ornamental metalwork project from rust, metalizing is another option worth considering for some exterior scenarios. Metallizing also applies a protective zinc layer like in galvanizing, but it is sprayed onto the piece instead of dipped. This allows fabricators to perform metallizing in house, as well as metallize pieces that are too large for hot dipped galvanizing. However, consider these disadvantages when evaluating metallizing as a potential option:
– Uniformity of the applied zinc layer will depend on the experience of the operator; some variation, and thus corrosion protection, are to be expected.
– Will not reach interior or difficult-to-access surfaces such as the area between a railing caprail and channel. This means that rust is guaranteed to develop in these areas and propagate outward.
– Reduced zinc layer density compared to hot dipped galvanizing.
At the end of the day, we recommend metallizing as a great option when hot dipped galvanizing isn’t a possibility. It will provide better rust protection, longevity, and lower lifetime maintenance requirements than going with only paint or powder coat finishing.
Do your projects use hot dipped galvanizing?
We want to hear from you! Tag us on social media and let’s share ideas, experiences and the all-important finished project photos.
Hot dipped galvanized accessories in stock and ready to ship
We offers several pre-galvanized components and décor pieces to accelerate your project:
- 35-2-26G; Available for 1”, 1-¼” and 1-½” sq
- DJA 145; Available for 1”, 1-¼” and 1-½” sq
- 46/14; Available for 2” sq
Gate Cane Bolt
- DJA 72; Available in 5/8” rd and 25/32” rd
Decorative railing planter
Decorative steel railing planter$160.00 – $240.00