Heat Coloring Steel

5 Essentials for Mastering the Art

Why Use Heat Colors to Patina Your Steel Art?

Though you can alter the colors of metal artificially, when we think of elemental metallic colors, we typically think of various silver, gold, and copper colors, depending on the particular metal or alloy.

Steel color ranges from the dark fire scale grey of hot-rolled steel and the lighter silvery grey of cold-rolled to the satin luster of a sandblasted or wire-brushed surface and the bright reflectivity of freshly ground steel.

When you add variation in abrasive scratch pattern angle found in decorative grind patterns and the subsequent color variation from reflected light, the value range of uncolored steel is nearly infinite.

Just as black and white photographers capitalize on tonal value, artists can do a lot with the contrast these greys and silvers offer, but many of us have an eye for the entire color spectrum and look for ways to patina our metal 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 intend to change the color of the metal without obscuring the metal’s innate character.

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

I’ve been making heat-colored steel wall art since the early ’90s. This page outlines five key elements of the process I’ve found to be essential for getting repeatable results.

If you’d like to further enrich your metal arts knowledge and practice, I’m nearly finished creating an online course to share what I’ve learned about heat coloring, decorative metal grinding, and innovative ways to combine the two.

In the meantime, this page, and my Free 5-Step Guide ‘How to Make Heat Colored Steel Engravings’ will introduce you to this unique and extraordinary medium and provide a framework to follow when you’re ready to give it a try.

The Heat Color Spectrum

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.
The colors of metal you can achieve by heating steel with a torch.

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 400º to 700º 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.

An example of metal wall art made using decorative metal grinding techniques.

Though heat colors are beautiful by themselves, they really come to life when you apply them over decorative grind patterns.

Heat Colors Are Not Purely Decorative

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. 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.

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. 

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 people experience when heat coloring.

What You'll Need

1. Ensure You are 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.

2. Use a torch sized for the work piece.

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 heat to keep the steel from cooling in one area while you heat another.

A large propane weed burner is an excellent all-around heat coloring torch.

3. Use a regular torch pattern over the entire surface.

When you are heat coloring steel, using a regular pattern as you pass the torch across the work will help you achieve an even heat. Vary the direction now and then to ensure complete coverage.

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

When the first straw color appears, adjust your heating pattern to account for any cold spots.

4. Take your time as you ease up to the desired color.

A few degrees separate the various heat colors, so proceed slowly, giving the heat time to soak the steel thoroughly.

Use each color that appears as a visual reference for the next.

5. Patience is Everything

Practice, practice, practice. Scrap steel is your friend. Grind it to bare metal and pick up your torch.

I’ve been making heat-colored steel metal art for nearly thirty years, and I’m still learning and refining the process of heat coloring steel.

That said, if you’re handy, you can pick up the basics pretty quickly.

And if you’re interested in learning more, I’m putting together an online course that will dive deep into the nuances of heat coloring, tools and abrasives, advanced grinding patterns, and other techniques for making heat colored steel artwork.

Every medium has its workflow.

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

And as heat-colored steel engraving is a process of finish-it-as-you-go because you texture and color areas working from hot to cold, you develop all-new ways of reconciling the current stage of progress with your intended result.

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’m nearly finished with my online course, The Art of Heat Colored Steel Engraving. Enter your email below to download the free guide and be added to the waitlist.

In Conclusion

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

One of the things I love so much about heat coloring steel is, no matter how skilled you become at achieving an effect that conveys the character and feel of your subject; there are always variables beyond your control that may enhance the work you are doing.

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.

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