Heat Coloring Steel

5 Essentials for Mastering the Art

Heating steel initiates a chemical reaction between iron and oxygen that creates a thin oxide layer on the metal. The thickness of the oxide layer determines the resulting colors.

Heat colors develop in the 400ºF to 700ºF range, with the lowest temperature color being a light straw color and the hottest dark green.

You can apply specific heat colors to bare steel using a torch to control the temperature and produce the desired result.

This image shows the rainbow blend of colors of metal you can achieve by heating steel with a torch, as seen in a lesson from my signature metal art course, The Art of Heat Colored Steel Engraving. 

More on that and my online heat coloring workshop further down the page…

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 a layered metal and wood wall piece made using heat-colored steel and decorative grinding.

The Heat Color Spectrum

When you color your metal art using heat, you can apply the specific heat colors in distinct, isolated areas or across broader sections as colorful gradients.

When the colors first begin to run, you’ll see a hint of light straw. After that, it will gradually darken as the temperature rises, transitioning to orange-red and then to purple.

Next comes dark blue, light blue, and a light grey-green. And, if you continue to heat, you’ll notice the colors run again, but in more pastel shades before turning to dark green and ultimately fire-scale gray.

Although a degree is a degree, many factors besides temperature come into play when heat coloring steel.

The surface you color, your heat coloring technique, and the work environment can affect the resulting heat colors.

Subtleties of Color

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’ve dedicated an entire module to decorative grinding in my Art of Heat Colored Steel Engraving course.

Why Use Heat Colors to Patina Your Steel Art?

There are many ways for artists to add color on metal.

Unlike paint, whose primary purpose may be protecting the surface from the elements, when we choose patinas for metal artwork, we prefer to change the color of the metal without obscuring the metal’s innate character.

One of the beauties of heat colors is how they color metal while retaining its dynamic, reflective qualities.

Nevertheless, many artists struggle to achieve consistent results with heat colors.

I’ve identified five elements that play a vital role in your overall success with heat colors.

When you have each of them dialed in, they will help you harness the spontaneity, beauty, and character heat colors offer to bring your artwork to life.

These five elements are

  • Your Workspace
  • Your Heat Source
  • Your Technique
  • Your Approach
  • and Your Ingenuity

I cover each of them in detail in my heat coloring workshop.

"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.

Functional Uses for Heat Colors

Heat colors have been around 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.

Want to learn how to make heat-colored steel engravings in your artistic style?

How to Color 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. 

I’ve been using heat colors to patina my steel wall art since the early ’90s.  This page contains a few tips I’ve found to be essential for getting repeatable results with all the heat colors from light straw to dark green and all the colors in between.

Whether you’re tempering a tool or adding the finishing touch to your latest metal sculpture, these pointers will help alleviate some of the common frustrations you may have experienced when heat coloring.

And, if you have a couple of hours and want to take control of heat coloring and get consistent results and predictable colors, check out my online heat coloring workshop, Heat Coloring Steel – 5 Essentials for Mastering the Art

PS. It’s only $27

Here's What You'll Need…

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.

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 color. 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.

Your torch needs to provide enough Btu’s to keep the steel from cooling in one area while you are heating another.

But even with a suitably sized torch, you have to proceed slowly, giving the heat time to soak the steel thoroughly.

Use a regular torch pattern over the entire surface.

Using a regular pattern as you pass the torch across the work will help to achieve an even heat.

You can take it a step further and vary the direction now and then to ensure complete coverage.

The shape of your steel also comes into play when heat coloring.

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

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.

And remember to use each subsequent color that appears as a visual reference for the next.

Patience is Everything

Take your time as you ease up to the desired color. If you proceed too quickly, you run the risk of overheating and going beyond the intended color. Heating too fast is one of the most common mistakes artists tend to make.

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 working by trial and error and quickly learn to take control of heat coloring, take a look at my online heat coloring workshop.

I detail each of the five essentials for achieving success with heat coloring so you can get beyond the struggle and focus on your creative process.

Are you struggling to take control of heat colors?

Learn to get the colors you want, precisely where you want them?

I share exactly how to get consistent results with heat coloring steel in my 2-hour online workshop.

We’ll go into detail about each of the five essentials that are necessary for mastering the art of heat coloring.

The Heat Color Spectrum
– What are heat colors?
– Your heat color palette?
– How are they unique among patinas?

Your Workspace
– Basic safety considerations
– Workstation options
– Lighting

Your Heat Source
– Choosing the Right Torch

Your Technique
What affects the result
– Torch pattern basics
– Adapting your technique to the job at hand

Your Approach
– Putting Heat Colors to Work
– The typical heat coloring sequence
– Applying solid colors beside each other
– Creating even color gradients

Your Ingenuity
– Adaptation and Innovation
– Advanced heat coloring techniques

All for only $27

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
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

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.

Not ready for a workshop or course right now? If you’d like inspiration and information about heat coloring, decorative grinding, and my metal art process, subscribe to my metal art newsletter.

You’ll also get instant access to my Free 5-Step Guide, ‘How to Make Heat Colored Steel Engravings’

5-step artists guide - How to make heat colored steel wall art

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 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.

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