Heat Coloring Steel

Five Essentials for Repeatable Results

Whether you’re adding a splash of color to a plasma-cut shape or creating an elaborate metalwork picture on steel, heat colors offer a rainbow palette of colors for your artistic expression.

There’s a touch of alchemy in the process and nothing quite like watching the colors run as you play your torch across the steel.

The immediacy of the transformation has a magical and unpredictable quality, making the patina process both extraordinarily satisfying and somewhat suspenseful.

Yet, the spontaneous nature of using a torch to color your metal art poses several challenges for achieving consistent results, and metal artists often struggle to get the effects they’re after when using heat colors to patina their art.

Over the last three decades of making heat-colored metal art, I’ve been able to identify the critical factors that allow me to get repeatable results with the full spectrum of heat colors, from light straw through the dark green.

Critical Factors for your Success

Whether you’re tempering a tool or adding the finishing touch to your latest metal sculpture, a clear understanding of the variables that influence your success will help alleviate some common frustrations so familiar with heat coloring.

Then, you can get on with your creative process to harness the spontaneity, beauty, and character of heat colors that can bring your metal art to life.

The Heat Color Spectrum - Heat coloring is one option for adding color on metal. The gradation of heat colors from light straw to dark green.

From your workspace and technique to your heat source and approach, mastering these basics will free you up to focus on your creative process unhindered by technical challenges.

With each dialed in, you’re free to adapt them to your artistic style, using your ingenuity creatively implement what you’ve learned.

This page contains heat coloring tips and information about my comprehensive online metal art course and the heat coloring workshop I’ve put together to help you fast-track your learning.

In this creative-edge metal wall art print of my layered steel and wood heat-colored steel engraving, a happily breaching humpback whale interrupts a seagull's evening meal.
Unexpected Company is metal and wood wall art made with layers of heat-colored steel and decorative grinding.

Online Metal Art Course and Heat Coloring Workshop

Learn the Art of Heat Colored Steel Engraving

Learn and master the entire process of making heat-colored steel engravings in your artistic style Comprehensive 6-Module Metal Art Course

Take Control of Heat Coloring Steel

Take the guesswork out of getting consistent results and predictable colors, Heat Coloring Essentials – Taking Control of Heat Coloring Your Metal Art.

Free 5-Step Guide – How to Make Heat Colored Steel Engravings

Enhancing the Metal's Unique Character

A happily breaching humpback whale interrupts a seagull's evening meal in this layered heat colored steel and wood relief.

When choosing patinas for metal art, we typically want to change the color of the metal without obscuring its metallic character.

Heat colors color the metal while enhancing its dynamic, reflective qualities and are directly influenced by any decorative surface grinding.

Unlike coloring steel with paint and opaque patinas, heat colors are transparent and integral to the substrate.

Though you can get transparent effects when staining steel, heat colors are an attractive natural alternative to commercial metal stains, having unique characteristics you won’t find in off-the-shelf products.

There are many approaches to applying heat colors in both isolated areas and across broader sections as colorful gradients.

The Challenge of Stopping at the Right Color

The color of metal can be altered with heat. This heat color chart shows the corresponding temperatures for each color in the heat color spectrum.
This heat color temperature chart illustrates the rainbow gradient of colors of metal achieved by heating steel with a torch along with their corresponding temperature.

Heating steel initiates a chemical reaction between iron and oxygen, creating a thin oxide layer on the metal. Its thickness determines the resulting colors.

As you can see in this heat color temperature chart, the colors begin to run with a hint of light straw, gradually darkening as the temperature rises.

They transition to dark straw, then orange-red and purple. Next comes dark blue, light blue, and light grey green.

As you continue to heat, you’ll notice the rainbow of colors run again in more pastel shades before turning to dark green and, ultimately, fire-scale gray.

Because heat colors develop in a narrow 400ºF to 700ºF temperature range with only a few degrees separating each color,  it can be difficult to stop heating at the desired color.

The full range of colors may appear in a narrow band or extend across a broad area, depending on how you control your heat source.

Factors to Consider When Coloring Steel With Heat

When it comes to changing the color of metal, heat coloring is one of the more ‘natural’ methods, as it doesn’t require additional chemicals, pigments, or coloring agents.

Coloring steel with heat is a pretty simple process. However, there are a few things to keep in mind to achieve consistent results.

Variables to Consider

A lone mammoth gazes across a barren winter landscape into a late Pleistocene sunset in the watchful presence of its ancestors.

To successfully apply heat colors, you must compensate for many factors besides temperature alone.

The cleanliness and texture of the surface you are coloring, its thickness and shape, the weather and work environment, the soak time, your torch size, fuel, and torch pattern are some things that affect how the heat colors develop.

Knowledge, practice, and experience enable you to adapt to each situation, thus improving your chances of successfully getting the effects you’re after in your metal art.

Ensure You're Working in a Safe Environment

Basic shop safety is beyond this article’s scope, and you should always familiarize yourself with acceptable safety practices and follow the instructions for using your equipment.

Before you begin, be sure the work area is free from flammable materials and tripping hazards.

And be sure you have a working fire extinguisher at the ready.

Familiarize Yourself with the Heat Color Temperature Chart

Though it’s not necessary to know what temperature each color appears at, you can see from this chart that only a few degrees separate the various heat colors.

A heat color temperature chart is a handy reference but actual temperature values don’t really come into play when you’re coloring your artwork.

Unless of course, you use a heat treating oven. In the absence of a suitably sized oven, the tool of choice for heat coloring is a torch.

With an oven, you can let the metal soak long enough to achieve a uniform temperature, though soaking time will also come into play. With a torch, the challenge of creating an even heat throughout the workpiece is in your hands.

Use a torch sized for the work piece.

This example of heat coloring steel shows the process of coloring the ocean layer of piece of multi-layer metal wall art with the heat from a large propane torch. For larger piecs of thinner steel, I do the coloring from one side to the other rather than with a uniform even heat on the whole piece.
A large propane weed burner is an excellent all-around heat coloring torch

When you are heat coloring steel and want to achieve an even color across the entire piece, it’s best to create an oven-like environment.

Trying to heat a large piece of steel with too small a heat source can be futile. Your torch needs to provide enough BTUs to keep the steel from cooling in one area while you are heating another.

But even with a suitably sized torch, you must pace yourself, giving the heat time to soak the steel thoroughly.

Pay Attention to Your Torch Pattern

An irregular torch pattern can make it difficult to achieve an even heat. The shape of your steel also comes into play when heat coloring.

For example, when coloring an unevenly shaped piece of steel, you’ll need to adapt the torch pattern to accommodate projections that may heat and cool more quickly.

Nonetheless, when the first straw color appears, you’ll have a visual reference for adjusting your torch pattern to account for any hot or cold spots.

Though it’s a speedy timelapse, the following video illustrates my typical torch pattern.

Patience is Everything

Take your time as you ease up to the desired color. Heating too fast is one of the most common mistakes artists tend to make. And, practice, practice, practice.  Scrap steel is your friend. Grind it to bare metal, pick up your torch, and color it. There’s a lot to learn.

 I’ve been making heat-colored steel metal art for nearly thirty years and am still developing and refining my techniques for heat-coloring steel.

If you’d like to avoid learning by trial and error and quickly learn to take control of heat coloring, take a look at my online heat coloring workshop.

I detail the essential factors for achieving success with heat coloring so you can get beyond the struggle and focus on your creative process.

Variations in Reflected Light

Though heat colors are beautiful in their own right, they really come to life when you combine them with variations in the inherent color of steel as light reflects from the surface of decorative grind patterns.

A painter can model forms and suggest subtle variations of color found in nature by mixing different values of color.

In heat-colored steel engraving, the metal artist uses decorative metal grinding to create subtle variations in the reflected light and, in turn, variations of color value and the suggestion of form, motion, transparency, and material.

I teach the entire process of making heat-colored steel engravings in my signature online course, The Art of Heat Colored Steel Engraving.

And if you’re particularly interested in decorative grinding, I’ve dedicated an entire module to it.

Every medium has its workflow

Just as your inspiration for learning new skills holds you to the course throughout the learning process, your vision for each finished piece guides your every action during the creative process.

Unlike working with many mediums, heat-colored steel engraving is a process of finish-it-as-you-go. Because you have to texture and color areas of your design sequentially, working from hot to cold, you develop all-new ways of reconciling the current stage of progress with your vision of the finished piece.

Each section you complete reinforces, clarifies, or alters that intention. And when you add the final silver highlight, you are greeted with what will likely be a combination of familiarity, surprise, and wonder.

I cover every detail of this metal art process in my metal art course, The Art of Heat Colored Steel Engraving.

Take Control of Heat Coloring Your Metal Art

In my 90-minute online workshop, Heat Coloring Essentials – Taking Control of Heat Coloring Your Metal Art, I share exactly how to get consistent results with heat-coloring steel.

The workshop covers the essential factors necessary for mastering the art of heat coloring.

The Heat Color Spectrum
– What heat colors are
– Your heat color palette
– How do heat colors set themselves apart from other patinas?

Your Workspace
– Important safety considerations
– Optimal workstation design
– Lighting considerations for best results
– Workpiece support configuration

Your Heat Source
– Choosing the Right Torch
– Choosing the right fuel
– Torch Size vs. Workpiece Size

Your Technique
– Factors that affect the result
– Torch pattern basics
– Adapting your technique to unique shapes and special situations

"My biggest single problem is consistency and control of color."

I have several years experience with CNC cut artwork and heat coloring as primary decorative accent. – Biggest single problem is consistency and control of color.

Coloring the ocean with a large propane torch. For larger piecs of thinner steel, I do the coloring from one side to the other rather than with a uniform even heat on the whole piece.
I’m already using heat coloring, but always ready to learn more.
Coloring the ocean with a large propane torch. For larger piecs of thinner steel, I do the coloring from one side to the other rather than with a uniform even heat on the whole piece.
Pat G.
Metal Sculptor and Blacksmith
I do metal art with painting only have not tried heat coloring yet but would love to learn. I have a plasma table so I cut out all sorts of things from sheets of flat steel mostly 26 gauge. It looks like it is something that I could incorporate with what I'm cutting out with my plasma table
Coloring the ocean with a large propane torch. For larger piecs of thinner steel, I do the coloring from one side to the other rather than with a uniform even heat on the whole piece.
Bruce P.
Metal Artist

Functional Uses for Heat Colors

Artists and craftspeople have used heat colors since time immemorial.

If you’ve worked with steel, you’ve seen them appear as you weld. And if you’ve held a tool to the grindstone a bit too long, you’ve discovered the hard way just what that blue color can mean.

As I learned from Alexander Weyger’s book ‘The Making of Tools,’ blacksmiths, toolmakers, and bladesmiths have long used heat colors, or temper colors to gauge the hardness of steel during the heat-treating process.

Each color in the heat color spectrum corresponds with a specific temperature and hardness.

Blue for springiness, straw for woodcarving chisels, etc. When you temper a tool, watching the colors run on the bare steel provides the necessary cue for quenching the tool for a specific end purpose.

I’d made a good many wood and stone carving tools before I ever considered heat colors as a patina for artwork. 

But that’s another story

In Conclusion

Heat coloring may be a perfect choice if you’re looking for ways to enhance the color of metal, whether for artwork or coloring steel for industrial uses.

It takes some time to master, but the rewards are many.

One of the things I love so much about heat coloring steel is that no matter how skilled you become at achieving a particular effect, there are always variables beyond your control that may enhance your work.

The wind and the weather when heating, the degree of surface cleanliness, imperfections in the steel, variations in surface texture, compensating for hotter and colder spots in contact with the support, and uneven heating are just a few of the things that can influence the way the heat colors ‘take.’

It takes patience to learn to mitigate those you can’t live with and on-the-spot decision-making to embrace those that further your artistic vision.

The more proficient you become with controlling your torch and applying heat colors to your metal art, the more you can focus on the creative process and what inspired you to make your art.

Visit my online metal wall art gallery to see my current selection of contemporary metal art.

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