How to Blue a Carbon Steel or Cast Iron Pan

Word on the street is that you need to “blue” your carbon steel or cast iron pan. What’s the deal?

What is Bluing?

Bluing, or blueing is the process of adding a black oxide layer on your steel. This can produce a bluish or blackish tint to the metal, hence the name.

Bluing has been used in gunsmithing, knifemaking, machining and many other applications to add corrosion resistance and visual appeal to the metal. There are many different ways to blue a metal, some involving acids, chemicals, heat or a combination of the three. While most applications use specific processes, blueing a pan can be done with only heat.

What Do I Need to Blue My Pan?

First you must determine what type of metal your pan is composed of. Bluing cannot be done on non-ferrous metals like aluminum because of the lack of iron. While bluing can be done on stainless steel, it requires chemicals and a more elaborate process. While it’s not common to blue a stainless steel pan, you can season it similarly to a cast iron or carbon steel pan to reduce sticking on the surface.

Most home cooks will be bluing a carbon steel or cast iron pans. This process converts the iron in the outer layer of the pan to magnetite (Fe3O4). This darkens and “blues” the outer layer forming the protective and visual appearance pictured below.

You will also want to make sure your entire pan is capable of taking the heat. Some carbon steel pans are not oven safe and may have handles that will deform in the process. Check with the manufacturer to see if the pan is capable of taking heat of over 500F for up to 30 minutes.

Clean your pan.

First you must ensure your pan is clean from any other seasoning or coatings. These can polymerize if heated and make the pan much more difficult to season and use properly. Bluing is easiest when the pan is new without any coatings. Most cast iron pans are pre-seasoned so it is recommended to sand blast or sand down the coating to bare metal. Most carbon steel pans come from the factory lightly coated in a protective oil. This can typically be removed with dish soap and scrubbing. Check the instructions from the manufacturer if in question.

Heat to Blue!

Next is to determine what heat source you have access to. One of the easiest ways to blue a pan is to heat it over an extremely hot flame such as a wok or gas range burner. New woks are cleaned then blued quickly by rotating the pan over the flame.

The heat source will need to reach 500-600F or 260-315C. Be sure to slowly increase the heat on thick pans to reduce the thermal shock and prevent cracking. Woks are typically thinner and therefore blue quicker than cast iron or carbon steel pans.

Another way to blue your pan is to heat it in the oven. Slowly increase the heat in several bursts to temper the pan to the highest setting on your oven. Leave the pan on the hottest setting for 30 minutes and then let it cool. The pan should have the bluish tint after the process is over. Season the pan as you normally would and you’re ready to cook on your blued pan!