Metals are often thought of as strong, durable and long-lasting, and generally speaking, this is correct. However, if the metal’s surface is not sealed with a protective coating, it can corrode or rust. Metal outdoor furniture loses visual appeal and eventually its structural integrity. That’s why metal surface coatings are so important. They protect the metal and help street furniture last longer with less maintenance. Read about the metal surface coatings commonly used by outdoor street furniture manufacturers to make durable furniture.
What are metal surface coatings?
Metal surface coatings are protective layers applied to metals like stainless steel and aluminium to stop them from rusting, wearing down, or breaking over time. When these metals are used as street furniture materials, a coating acts as protection against corrosion.
Why are surface coatings used for metal furniture?
Street furniture is built to last, but metal can still break down without protection. Surface coatings are used because they help:
Protect Against Harsh Weather
Street furniture is exposed to rain, heat, sunlight, pollution, and dust every day. A surface coating works like a shield to protect the surface and the metal from rust and corrosion.
Improve Appearance
Surface coatings improve the look of street furniture by adding smooth finishes, colours, and giving it a professional appearance.
Reduce Maintenance Costs
Street furniture without a coating may need repainting or replacement more often. The right coating can reduce ongoing costs and add years to the life of outdoor furniture.
See our stainless steel furniture guide to understand the science behind surface coatings.
Common Metal Surface Coatings for Street Furniture
Below are the most common coating types used on metal street furniture.
Zinc Electroplating
Zinc electroplating is a process where a thin layer of zinc is added to metal using electrolysis. Generally, street furniture items that are zinc-plated are also painted. Zinc plate and powder coat can offer good service lives of up to 15 years.
Best for:
- Low-corrosive outdoor environments
- Light-duty street furniture components
Pros
- Lower cost
- Can be painted over to match the colours of your organisation or council’s branding
Cons
- Not ideal for coastal or corrosive environments with vandalism and “hard” use
- The thin coating may wear faster over time
Hot Dip Galvanising
Hot dip galvanising is one of the most trusted coatings for steel street furniture. The metal is dipped into a molten tank of zinc, leaving behind a thick protective coating. The high volume of zinc in the coating protects against corrosion. This coating is widely used for outdoor public furniture because it lasts a long time.
Initially, the metal has a bright silver look, but after several months, the furniture will take on a matt grey finish unless powder-coated.
Best for:
- Outdoor steel furniture
- Parks, streets, and high-use public areas
- Most harsh environments with vandalism
Pros
- Excellent corrosion protection
- Long lifespan outdoors
- Strong coating for heavy-duty use
- Reasonably economical choice
- Optional secondary finish, such as powder coating, for a visually appealing finish
Cons
- Work with a trusted supplier, as several steps are needed to ensure good adhesion and finish, like etching and de-gassing
- Dags (hardened zinc drips) and slag (weld impurities) are imperfections that may form if the coating isn’t done properly. Further labour is required to ensure the integrity of the galvanised coating is consistent.
Mechanical Galvanising
Mechanical galvanising is mainly used for small metal parts like bolts, nuts, and fixings. Components are placed into a rumbling drum with zinc powder and plastic shot. The rotating action of the drum imparts the zinc onto the surface of the components.
Best for:
- Fasteners and small steel components
Pros
- Uniform, even coating with protection levels that match hot dip galvanising
- Strong rust protection
- Great for small hardware
Cons
- Not suitable for large furniture pieces
Zinc Rich Primers
A primer containing zinc is applied to the material prior to a finish coat. This is done by powder coating or a wet coat paint process. Depending on the type of primers and paints used, protection levels vary. It is applied before a final topcoat, like powder coating. This system offers a medium level of protection.
Best for:
- Painted street furniture
- Projects needing colour matching
- Areas where furniture is not prone to physical damage
Pros
- Adds rust protection under paint
- Works well in multi-layer systems
- Cost-effective in some applications
Cons
- Usually, a more expensive process
- Not as durable as galvanising alone
- Performance depends on the topcoat quality
Zinc Plated Sheet Steel
An alloy of aluminium and zinc (zincalloy, zincallume, etc.) or zinc is applied during manufacturing. The sacrificial properties of zinc protect the raw edges of the metal, even when cut to shape.
Best for:
- Light outdoor use
- Low-corrosion environments
- Used in fabrication projects
Pros
- Affordable
- Basic protection from rust and corrosion
- Useful for fabricated panels and parts
Cons
- Cost-effective method
- Less durable than hot-dip galvanising
- Some areas may become vulnerable to corrosion if large areas of the finish are damaged during fabrication
Powder Coating
Powder coating is a baked-on finish. The metal components are coated with a primer or a layer of powdered polymer. The coated parts are baked in an oven to melt the polymer, resulting in a very smooth and consistent finish. Powder coating is popular because it looks clean and comes in many colours.
Best for:
- Decorative finishes and projects requiring specific colours
- Works on both steel and aluminium furniture
- Works best when applied over galvanised steel or a zinc primer
Pros
- Wide range of colours
- Smooth and consistent finish
- Cost-effective
- Resistant to scratches and fading
Cons
- Powder coating alone is not always enough to stop rust, as it is only an aesthetic finish
- If water gets under the coating, corrosion can spread unseen
2 Pak Painting
2 Pak paint is a two-part paint system that hardens into a strong protective coating. Components are coated with a primer and a two-part top coat. This top coat consists of a base and a hardener that offers a high-level finish.
Best for:
- Heavy-duty street furniture
- Tough outdoor environments
- High-traffic areas
- Projects that require colour matching
Pros
- Hard-wearing surface and high-level finish
- Better corrosion resistance than standard paint or powder coating because the base material is sealed from the atmosphere
- Professional appearance
Cons
- More expensive than powder coating
- If the surface underneath is damaged, corrosion and rust can spread under the paint
Anodising (Aluminium)
Anodising is a protective coating used only for aluminium. Components undergo an electrolytic passivation process used to increase the thickness of the natural oxide layer on the metal’s surface. In simpler words, aluminium naturally gains a skin that protects it from further corrosion. Generally speaking, all aluminium outdoor furniture should be anodised. This stops the surface from becoming cloudy and unsightly, particularly in corrosive environments.
Best for:
- Aluminium street furniture
- Coastal and marine environments with salty air
- Heavy-duty public use
Pros
- Excellent corrosion and rust protection as the natural outer layer of aluminium is protected
- Long-lasting finish
- Cost-effective process
- Can be powder-coated on top
Cons
- Only works for aluminium
- May not suit all colour and finish requirements
Frequently Asked Questions (FAQs)
What is the best coating for outdoor street furniture?
The best overall option is usually hot-dip galvanising followed by powder coating. It provides long-lasting rust protection and a clean finish.
Does powder coating prevent rust?
Powder coating helps protect metal, but it is not always enough on its own. If moisture gets underneath, rust can spread. It works best over galvanised steel.
What coating is best for coastal street furniture?
Coastal street furniture needs strong corrosion resistance. The best options are:
- Hot dip galvanising
- Galvanising + powder coating
- Anodised aluminium
Can street furniture coatings fail?
Coatings often fail due to:
- Poor surface preparation
- Scratches exposing bare metal
- Water getting under the coating
- Coastal salt exposure
- Low-quality paint systems
Choosing the right coating system and a trusted manufacturer reduces these risks.
Choosing the Right Coating Matters
Choosing the right metal surface coating improves durability, reduces maintenance costs, and keeps street furniture looking professional.
Draffin Street Furniture has vast experience with metal surface coatings. If you have any questions or need advice when specifying a surface coating, contact one of our friendly engineers. We love to put our experience and resources to work helping solve our customers’ problems.