How to Waterproof Metal

Although metal is naturally waterproof—as in it doesn’t let water pass through it—many metals are susceptible to rust and degradation if left in the rain for too long. Over time, the elements will begin to lay waste to your outdoor furniture and metal fabrications, causing you to replace them. But what if you could stop that process?

Waterproofing metal outdoor furniture and fabrications is an easy way to extend their life. Using just a few products and methods, you can stop water from damaging or rusting your belongings and save you the expense of buying replacements.

In this guide, we’ll give you a quick rundown on why you should waterproof metal surfaces and also walk you through a few simple methods for how to do it. Let’s get started!

How to Waterproof Metal

Why You Should Waterproof Metal Structures

Rust is more than just an aesthetic issue. As your metal surfaces begin to degrade in the rain, they will slowly lose surface hardness and become more brittle. If you don’t stop the rust from spreading, it will slowly make your outdoor furniture and fabrications unfit for use.

Furthermore, sitting on rusty furniture can be dangerous for you and your family. As metal rusts, it becomes jagged and can easily cut someone who sits on it. Cuts caused by rusty metal can quickly become infected and require you to seek out medical attention.

Therefore, if you are going to put metal surfaces outdoors, you should protect them from daily exposure to rain, snow, sleet, and other forms of moisture.

Why Does Metal Rust When It is Exposed to Water?

Rust is just one of the ways in which metal goes through a process called oxidation. As oxidation builds up, metal will become scarred with discoloration, pitting, or even begin to flake off like dandruff. Another common way to say this is that it begins to corrode.

At a molecular level, oxidation happens because the oxygen in the water begins to trade electrons with the metal. As oxygen trades more and more electrons, the metal becomes ionized as oxidation or, more commonly, rust. The oxidation slowly builds up and takes over the rest of the steel or aluminum.

Depending on where you live, you may have to deal with oxidation more than others!

 If you live near the ocean or a lake, in a rainy area of the country such as the Pacific Northwest, or in humid regions such as swamp and marshlands, your metal outdoor equipment will be more at risk of corrosion. Saltwater in particular can wreak havoc on metal far faster than standard rain or humidity.

So, what can you do to waterproof your metal and prevent it from breaking down before its time?

How to Waterproof Metal

Waterproofing Metal the Easy Way

No matter how dedicated you are to preventing rust and degradation, understand that no single method will permanently save your outdoor equipment. Some methods will help preserve them better but the longer you want your equipment to last, the more work you’ll have to put in. Let’s start simple and then work towards the more involved methods.

Paint Your Metal Surfaces

Covering all metal outdoor equipment in a thick coat of waterproof paint is one of the easiest and fastest ways to get another 5 to 10 years of use. Oil-based paints are ideal for outdoor furniture, fencing, or barbecues and will be more effective than water-based paints thanks to the naturally water-repellant characteristic of oil. Oil paints also dry rigid and can stand up to dents and scratches.

POR-15 Semi Gloss Black Rust Preventive Paint

POR-15 Semi Gloss Black Rust Preventive Paint

  • Seals Rust Permanently
  • No Need to Remove Rust Before Applying
  • Lead-Free

Oil paint is, however, more expensive than water-based paint and can crack and fade over time. We recommend finding a product that has anti-fade protection already added to it. To get the best results, start by applying an oil-based primer and let it dry before applying the paint. You can find sprayable paints or use a brush to get a thorough coat.

RP-342 "Heavy" Rust Preventative Spray

RP-342 "Heavy" Rust Preventative Spray

  • Our strongest, longest-lasting & fastest-drying
  • Durable & tough
  • Easy-to-apply

Use a Powder Coating

In addition to adding a new coat of paint, applying a powder coat to your metal equipment will extend the lifespan of your outdoor metal fixtures. Aluminum, in particular, is well suited to powder coatings because it generally corrodes faster than steel. But be aware, powder coatings are harder to apply than paint.

Eastwood Hotcoat Powder Coat

Eastwood Hotcoat Powder Coat

  • Provides extremely durable finish
  • Contains no environmentally harmful solvents
  • 100% virgin powder

Powder coatings come in two varieties—thermoplastics and thermosets. At their most basic elements, though, both are essentially powdered enamels that you spray onto a metal surface and then heat up to cure them as a coating. The spraying process is usually done using an electrostatic spray gun and manufacturers will even use curing ovens to finish the job.

TPSHKE Cordless Electrostatic Spray Gun

TPSHKE Cordless Electrostatic Spray Gun

  • Electrostatic sprayer
  • Cordless and portable
  • Efficient design

At home, you can make do with a toaster oven or even your kitchen oven. The only requirement is that the powder reaches at least 350 degrees Fahrenheit for 20 minutes. If you cannot reach that temperature, the coating will not develop a complete seal.

Galvanize Your Metal Using Zinc

This final method is not something you should attempt at home. However, if you want the maximum amount of life from your metal fixtures, you can take them to be galvanized in zinc. Galvanization involves dipping your metal equipment into molten zinc and allowing it to cool to create a solid zinc barrier.

The zinc acts as the first line of defense and will oxidize before the rest of the metal, providing up to 50 years of added protection. However, once the zinc has decayed away, it may be difficult to galvanize your fixtures a second time if they have already been set in place. Galvanization can also be expensive for large equipment.

Waterproof Any Metal

Depending on the type of equipment you want to waterproof and how much effort you want to put into it, you should be able to safely put another 5 to 10 years of life into your outdoor furniture, fencing, fixtures, or appliances. For long-term waterproofing, you’ll have to invest in zinc galvanization but for shorter-term protection, a new coat of powder or paint will do just fine.