How to Accelerate Rust on Corten Steel?

Corten steel, also known as weathering steel, is one of the most fascinating materials used in modern design, landscaping, and architecture. Its distinctive rusty color gives an authentic, natural, and industrial character to any project — from sculptures and garden planters to building façades and outdoor furniture.

However, one question comes up again and again: how can you accelerate the rusting of Corten steel in a safe, controlled, and efficient way?

In this comprehensive guide, we will explore how rust forms naturally on Corten steel, why it’s not always ideal to wait for nature to take its course, and how to use the professional Corten+ method to achieve the perfect rust finish — safely, without acid, and in just a few hours.

What Is Corten Steel and Why Does It Rust Differently?

To understand how to accelerate rust on Corten steel, it’s important to first understand what makes this metal so unique.

Corten steel (short for CORrosion resistance and TENsile strength) is a special alloy of steel that contains copper, chromium, nickel, and phosphorus. These additional elements allow it to develop a protective layer of oxidation when exposed to air and humidity.

This protective layer, known as patina, acts as a natural barrier between the environment and the underlying steel. Once the patina has formed, it stabilizes and prevents further corrosion.

In other words, unlike ordinary steel that continues to rust until it disintegrates, Corten steel stops corroding once its surface has oxidized enough.

Natural Rusting: A Long and Unpredictable Process

In theory, you could simply expose Corten steel to outdoor weather and let nature do the work. Over time, with alternating rain and sun, the metal would start to develop its orange-brown patina.

However, this natural process can take many months — even years — depending on your local climate.

Factors That Influence Natural Rust Formation:

Humidity levels: Rust forms faster in humid or coastal environments.
Rain exposure: Water accelerates oxidation, but too much can cause run-off stains.
Air pollution: Pollutants and salts can alter the rust color and texture.
Temperature: Low temperatures slow down oxidation.
Airflow: Poor ventilation can create uneven or blotchy rusting.

Because of these variables, natural weathering is unpredictable. Some areas of the metal may rust faster than others, leading to patchy, uneven colors. Inconsistent patina can be frustrating, especially for designers, landscapers, or homeowners looking for a clean, uniform finish.

That’s why many professionals use controlled oxidation — an intentional method to accelerate the rusting process safely and obtain a consistent, aesthetic result in record time.

Why Not Use Acid-Based Rust Accelerators?

A common mistake made by DIY enthusiasts and even some professionals is to use acid-based products (such as hydrochloric acid, vinegar, or certain industrial cleaners) to make the steel rust faster.

While acids do make steel turn orange quickly, they also destroy the chemical integrity of the Corten steel.

The Problem With Acid Treatments

Acids attack the steel’s surface, eating away at the protective alloy components (especially copper and chromium).
The corrosion does not stop — even after the surface looks rusty. The acid keeps reacting with the metal beneath the patina, which can eventually cause holes, flaking, or structural weakness.
Acid fumes are dangerous to inhale and require protective gloves, masks, and goggles.
The acid reaction must be neutralized with a stop bath, which adds complexity and cost.

In short: using acid might seem like a shortcut, but it ruins your steel and compromises safety.

The Corten+ Solution: Accelerating Rust Safely and Naturally

At Corten+, we developed a 100% acid-free rust accelerator that mimics natural weathering — but within just a few hours.

Our formula works by activating the steel’s natural oxidation mechanism instead of corroding it. The process is fast, uniform, safe for users, and completely respectful of the metal’s integrity.

Why Choose Corten+ Over Acid-Based Products

Feature	Acid-Based Accelerators	Corten+ Rust Accelerator
Composition	Contains acids	100% acid-free
Risk of corrosion	High (continues after application)	None
Safety	Toxic and corrosive	Safe and non-toxic
Neutralization needed	Yes	No
Color control	Difficult and uneven	Uniform, natural patina
Cost	High (requires multiple products)	Up to 3x cheaper

The Corten+ Rust Accelerator reproduces the effect of months of weather exposure in just one day, giving you full control over the color, tone, and depth of the rust.

Step-by-Step Guide: How to Accelerate Rust on Corten Steel

The rusting process requires three essential stages:

Preparation – Cleaning the steel surface
Oxidation – Applying the rust accelerator
Protection – Sealing the finish to prevent stains

Let’s go through each step in detail.

Step 1: Surface Preparation

The quality of your oxidation result depends almost entirely on how well the steel is prepared. If the surface is dirty, greasy, or covered in mill scale, the rust will not develop evenly.

Determine the Type of Corten Steel

Before anything else, identify whether your steel is hot-rolled or cold-rolled:

Cold-rolled Corten steel: thinner than 2.5 mm, smooth surface
Hot-rolled Corten steel: thicker than 2.5 mm, rough surface with mill scale

⚠️ Note: Always confirm with your supplier, as thickness alone is not a guaranteed indicator.

If It’s Hot-Rolled: Remove the Mill Scale

Hot-rolled steel comes with a layer called mill scale — a dark, hard coating formed during manufacturing. This must be removed to allow proper oxidation.

Option 1: Sandblasting (Recommended)
At Corten+, we recommend sandblasting or grit blasting to mechanically remove mill scale and create a slightly rough surface. This ensures perfect adhesion of the oxidation layer.

Option 2: Corten+ Descaler
If you don’t have access to a sandblaster, use the Corten+ Descaler (also known as Descaling agent).

Spray the product evenly on the steel surface.
Allow it to act for the indicated duration.
Rinse thoroughly with clean water.

Because the Corten+ Descaler is a powerful chemical, rinsing is crucial to eliminate residues and prepare the surface for oxidation.

If It’s Cold-Rolled: Remove the Grease Layer

Cold-rolled Corten steel has a protective oil coating to prevent premature rust. Ordinary degreasers won’t remove it completely — you need a special Corten steel degreaser.

Use the Corten+ Degreaser, specifically formulated for this tough industrial grease.

Apply generously over the surface.
Leave for several minutes to penetrate the oil.
Rinse thoroughly with water and let dry.

Once clean, your Corten steel is ready for oxidation.

Step 2: Accelerating the Rust with Corten+

Now comes the exciting part — creating that rich, natural rust patina in hours instead of months.

Application Instructions

Make sure the surface is clean and dry.
Shake the Corten+ Rust Accelerator well before use.
Apply it evenly using a sprayer or brush.
Allow it to react naturally with the steel surface.

Within a few hours, you’ll begin to see the first orange tones of oxidation. Over 24–48 hours, the surface transforms into a uniform, natural rust color.

If you wish to darken the tone, you can apply a second or third coat until the desired depth of color is achieved.

Best Conditions for Application

Temperature: Between 10°C and 25°C (50–77°F).
Humidity: Moderate; avoid heavy rain during the process.
Surface: Must be dry and free of dust or oils.
Environment: Avoid direct sunlight or strong wind while spraying.

The Corten+ Rust Accelerator works by gently activating oxidation without damaging the metal. Since it’s acid-free, you don’t need any neutralizing agent or rinsing afterward.

Step 3: Protecting the Rust Finish

Once your steel has reached the desired tone, it’s important to seal and protect it.

Without protection, rainwater can cause rust run-offs that stain nearby surfaces such as stone, concrete, or wood. The rust layer can also rub off onto clothing or skin on contact.

To avoid this, use the Corten+ Sealer — a protective varnish designed specifically for Corten steel.

Why Use the Corten+ Sealer?

Prevents rust drips and stains on the ground.
Keeps clothes and hands clean from rust dust.
Locks in the color at your preferred stage.
Maintains the matte, natural look of the steel.
Easy to apply with a spray or brush.

The Corten+ Sealer forms an invisible, breathable layer that preserves your patina without altering its appearance.

How to Apply the Corten+ Sealer

Wait for the steel to reach your desired shade.
Ensure the surface is completely dry.
Apply the sealer evenly across the surface.
Let it dry fully before handling or exposing to rain.

After sealing, your Corten steel becomes waterproof and stain-resistant, ideal for both indoor and outdoor applications.

Controlling the Final Color of the Patina

One of the greatest advantages of using Corten+ is color control.

When rusting naturally or with acids, the patina color evolves uncontrollably — from light orange to dark brown — over months or years.

With Corten+, you decide when to stop. Once the desired tone is achieved, simply apply the sealer, and the color will stay exactly as you want it.

This flexibility is particularly appreciated by architects and designers who need consistency across large installations or multiple projects.

Applications: Where Accelerated Rust Is Most Useful

1. Garden and Landscaping Projects

Planters, fire pits, edging, and garden screens made from Corten steel look stunning with a controlled rust finish. Using Corten+ Rust Accelerator, you can achieve a beautiful patina before installation — avoiding dirty run-offs later.

2. Architectural Facades

For large façades, consistency is key. Natural rusting can lead to uneven coloration between panels. The Corten+ method guarantees a homogeneous finish across the entire surface, enhancing visual harmony.

3. Artistic and Decorative Projects

Artists love Corten steel for its raw texture. Using Corten+, they can create the desired patina quickly and precisely, even indoors, without the risks associated with acid-based accelerators.

4. Indoor Furniture and Decoration

When using Corten steel indoors (tables, lamps, wall panels), natural rusting is impossible. The Corten+ Rust Accelerator creates the desired patina instantly, and the Sealer prevents rust transfer or staining in living spaces.

Frequently Asked Questions

How long does it take for Corten+ to produce visible rust?

Visible oxidation begins within hours, and full patina formation occurs in 24 to 48 hours depending on conditions.

Do I need to rinse the surface after using Corten+?

No. Unlike acid-based products, Corten+ does not require rinsing or neutralization. The process stops naturally when oxidation stabilizes.

Is it safe to use indoors?

Yes. Since it’s acid-free and non-toxic, Corten+ is safe for indoor use, provided the area is ventilated.

Can I use Corten+ on ordinary steel?

While designed for Corten steel, it can also be used on regular steel to produce a rusted look. However, the protective effect of Corten alloys will not apply, so sealing is strongly recommended.

Can I reapply Corten+ later if I want to adjust the color?

Absolutely. You can add another coat anytime to deepen the tone before resealing.

Comparing DIY Methods vs. the Corten+ System

Method	Time	Safety	Color Uniformity	Durability	Cost
Natural Weathering	6–12 months	Safe	Uneven	High	Low
Acid Treatments	1–2 days	Dangerous	Patchy	Poor	Medium
Corten+ System	2-4 hours	Safe & Acid-Free	Uniform	Excellent	Low (fewer products)

Corten+ delivers the perfect balance of speed, safety, and professional-quality results.

Maintenance Tips for Rusted Corten Steel

Inspect yearly: Check for any cracks or worn areas in the sealer.
Clean gently: Use water and a soft cloth — avoid harsh chemicals.
Reapply sealer every few years for long-term protection.
Avoid standing water: Ensure good drainage for outdoor items.
Store properly if moving Corten objects indoors or outdoors.

With these simple maintenance steps, your Corten steel will retain its unique charm for decades.

Why Professionals Choose Corten+

Corten+ has become the go-to solution for landscapers, architects, artisans, and metalworkers around the world. Here’s why:

100% acid-free technology — safe for you and your steel.
Fast, natural oxidation in 24 hours.
Perfectly even results across large surfaces.
Simplified process: no rinsing, no neutralization, no hazards.
Lower total cost: one integrated system for preparation, oxidation, and protection.
Global delivery: fast worldwide shipping through our network of carriers.

Whether you’re a homeowner or a professional, Corten+ gives you the tools to create and preserve perfect rust finishes every time.

Step-by-Step Recap

Step	Objective	Recommended Product	Purpose
1. Preparation	Clean and ready the steel	Corten+ Descaler / Degreaser	Remove mill scale or grease
2. Oxidation	Accelerate rust naturally	Corten+ Rust Accelerator	Create uniform patina safely
3. Protection	Seal and stabilize	Corten+ Sealer	Prevent stains and color change

Final Thoughts: The Art of Controlled Oxidation

Rust is often seen as a symbol of decay, but on Corten steel, it becomes a mark of beauty, authenticity, and endurance. The key is to control the process rather than letting nature take over.

With Corten+, you can accelerate the creation of that signature patina quickly, safely, and beautifully — without compromising the metal’s integrity.

Whether you’re building a modern façade, crafting a garden masterpiece, or designing a sculptural centerpiece, Corten+ gives you complete control over how your steel looks and lasts.

Where to Buy Corten+ Products

All Corten+ products — including the Descaler, Degreaser, Rust Accelerator, and Sealer — are available on our official website.

We offer fast international delivery, and our products are trusted by professionals across Europe and worldwide.

👉 Visit our site to explore the Corten+ complete treatment range and transform your Corten steel with confidence.