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Heat Coloring Steel

Five Essentials for Your Success

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

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

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

Yet, the spontaneous nature of coloring steel with a torch poses unique challenges, and metal artists can struggle to get consistent results.

In the thirty-plus years I’ve worked with heat colors, I’ve identified five critical elements for successfully achieving the desired effects.

This page introduces them and includes fundamental heat coloring tips and information on my Art of Heat Colored Steel Engraving course and Heat Coloring Essentials workshop, which I’ve created to help you fast-track your learning.

Whether you’re tempering a tool or adding a patina to your latest metal art, understanding the variables influencing your success can help you achieve the desired results. This will ultimately free you to make the most of the spontaneity, beauty, and character heat colors can bring to your metal art.

Five Critical Elements for Consistent Results

Mastering these five essentials will free you to focus on your creativity unhindered by technical challenges.

  1. Your Workspace – Although you can do heat coloring almost anywhere, several factors influence the safety, efficiency, and ease with which you work.
  2.  Your Heat Source – Choosing the right heat source for the job can make the difference between success and failure.
  3.  Your Technique – Your heating technique is perhaps the most significant factor in getting your desired results.
  4. With these three dialed in, you can adapt Your Approach to fit your artistic temperament and style and
  5. Use Your Ingenuity to innovate and make your work stand out.

Digital Metal Art Course and Heat Coloring Workshop

"There is no other course like this!"

The Art of Heat Colored Steel Engraving class is phenomenal! I learned new skills to add color, texture, and depth to my art - it really was a game changer! The course is comprehensive, well laid out, videos are well done, and you have lots of support along the way. This course will provide you with the knowledge to build your skills to take your work to the next level. There is no other course like this!


Enhancing the Steel's Unique Character

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

They allow you to patina the metal without obscuring its metallic character.

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

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

The Challenge of Stopping at the Right Color

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, which is a factor of temperature and soak time, 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.

Variables 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.

It’s a pretty simple process; however, 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.

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.

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

Pay Attention to Your Torch Pattern

An irregular torch pattern can make it challenging 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 must 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 and proximity to the metal to account for any hot or cold spots.

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

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

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.

There are many approaches to applying heat colors, whether in isolated areas or across broader sections.

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.

I’m already using heat coloring, but always ready to learn more.
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
Bruce P.
Metal Artist

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.

Not ready for a workshop or metal art course?

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