Heat Tarnish: Stainless Steel Pan Discoloration

Heat tarnish, or heat tint, on stainless steel pans is a common issue for home cooks and professional chefs alike. This rainbow discolouration is caused by a combination of chromium (found in stainless steel) and oxygen in the air, which creates a thin protective layer on the pan. When stainless steel is heated to high temperatures, the top layer oxidises and thickens, resulting in a rainbow hue. Although unsightly, this discolouration does not affect the performance or safety of the cookware. To remove the heat tint, a diluted vinegar solution and soft sponge can be used to scrub away the stain, restoring the pan to its original shine.

How to identify heat tarnish on stainless steel pans

Heat tarnish, or heat tint, on stainless steel pans is caused by a combination of chromium and oxygen. Stainless steel contains chromium, which helps to resist corrosion and rusting. When stainless steel is heated to high temperatures, the top layer oxidises and thickens, causing a rainbow tint.

To identify heat tarnish, look for a rainbow stain on your stainless steel pan. This will be a colourful film on the surface of the pan. The colours are usually in a range from yellowish to blue.

Heat tarnish is harmless and does not impact the performance of your pan. It is simply an aesthetic issue. However, if you want to remove the heat tarnish, you can use diluted white vinegar and scrub with a non-abrasive sponge. Then, rinse and dry the pan.

What causes heat tarnish on stainless steel pans

Heat tarnish, or heat tint, on stainless steel pans is caused by a combination of high temperatures and the chemical composition of stainless steel. Stainless steel contains chromium, a metal that helps to keep stainless steel pans from rusting or corroding. When stainless steel is heated, the top oxidized layer can thicken due to increased oxidation, resulting in a rainbow tint on the pan's surface. This occurs because as the layer thickens, it reflects light at different wavelengths, producing a range of colours.

The temperature of the pan increases over time, and so does the oxidation, typically resulting in a colour change from yellowish to blue. This phenomenon is not limited to stainless steel pans but is common in stainless steel items in general. While it may be unsightly, heat tarnish does not affect the performance of the pan or the food cooked in it. It is purely an aesthetic issue.

To remove heat tarnish, a diluted vinegar solution can be applied to the pan and scrubbed with a non-abrasive sponge. Alternatively, specific cleaning products such as Bar Keepers Friend or baking soda can be used to scrub off the stains.

How to remove heat tarnish from stainless steel pans

Heat tarnish, or "heat tint", on stainless steel pans is caused by a combination of chromium and oxygen when stainless steel is heated to high temperatures. This results in a rainbow stain that is simply an aesthetic imperfection and does not affect the cooking performance of the pan.

Using Vinegar

Splash some diluted white vinegar into the pan and wipe the area with a soft sponge before rinsing and drying the pan thoroughly. The acidity of the vinegar will help break down the thin oxidized rainbow layer while being gentle on your pans.

Using Bar Keeper's Friend

Create a paste with some water and Bar Keeper's Friend, then scrub it away with a non-abrasive sponge. Bar Keeper's Friend is a gentle yet effective commercial cleaner designed to clean without scratching or damaging stainless steel surfaces.

Using Baking Soda

Add a few spoonfuls of baking soda and enough water to cover the burnt areas of the pan. Bring this mixture to a boil and simmer until most of the water has evaporated. Turn off the heat and wait until the pan is cool enough to handle. Scrub away any remaining residue with a non-abrasive sponge and wash in hot, soapy water.

Using Boiling Water and Baking Soda

For bigger, tougher stains, add a small mound of baking soda to the centre of the pan and cover it with about 1/4 cup of water. Bring this to a boil and as the water evaporates, it will leave a film of baking soda around the walls of the pan that you can scrub off. When most of the water has boiled off, turn off the heat and use a long-handled brush or scouring pad to scrub away the residue.

Using Boiling Water, Baking Soda, and Submerging the Pan

For an even more intensive cleaning method, fill a larger pot or roasting pan with enough water to submerge your stainless steel pan. Add a generous amount of baking soda (about 1/4 to 1/2 cup) and carefully place your pan in the water. Bring the water to a gentle boil and let the pan cook for about 15 to 30 minutes. Remove the pan from the water and create an abrasive slurry with more baking soda and water to scrub away any remaining residue.

Using Commercial Cleaners

For lighter stains, commercial cleaners such as Bar Keeper's Friend or baking soda can be effective. Simply moisten the pan, sprinkle the cleaner onto the bottom to form a paste, scrub it into the stained areas, and then rinse. Repeat the process if necessary.

General Tips to Prevent Heat Tarnish

• Always allow your pan to cool completely before washing it. Submerging a hot pan in cold water can cause warping and disfiguration.
• Avoid using coarse scrubbers and harsh cleaning solutions like bleach or household cleaners, as these can scratch the surface and damage the finish of your pan.
• Prevent water spots by drying your pans immediately after washing.
• Only add salt to water once it has come to a boil to avoid "pitting corrosion", which can leave tiny but irreparable pockmarks in the bottom of your pan.
• Always heat your pan before adding oil, and then add food once the oil is hot.
• Allow cold foods to come to room temperature before cooking to prevent them from sticking to the pan.
• Do not rush the preheating process by using high heat, as this can lead to overheating your pan.

How to prevent heat tarnish on stainless steel pans

Heat tarnish on stainless steel pans is caused by a combination of oxygen and chromium, a metal often found in stainless steel, which creates a thin protective rainbow-coloured layer when exposed to high heat. While this discolouration is completely safe, it may be unsightly to some. Here are some tips to prevent heat tarnish on your stainless steel pans:

• Always let your pan cool down before cleaning. Submerging or soaking a hot stainless steel pan in cold water can cause irreparable warping.
• Avoid harsh cleaning solutions like bleach or household cleaners, as these can scratch your stainless steel and damage its finish.
• Stick to a cleaning routine. Clean your stainless steel pans and pots after each use to avoid a buildup of stains.
• To prevent water spots, always dry pans immediately after washing.
• Only salt water once it has already come to a boil. When water is salted pre-boil, "pitting corrosion" can occur, leaving tiny but irreparable pockmarks in the bottom of the pot.
• Always heat your pan before adding oil. Adding oil to a hot pan causes the steel to become "static", creating a temporarily non-stick surface.
• Take the chill off cold foods. Cold food is more likely to stick to a hot pan, so allow refrigerated ingredients such as meat, chicken, or fish to sit at room temperature for 10 to 15 minutes before cooking.
• Do not rush the preheating process by using high heat. Since high-quality stainless steel is effective at holding heat, preheating on high heat may lead to overheating your pan and burning your food.
• To prevent food from sticking, preheat your pan before adding oil, then wait until the oil is hot before adding your ingredients.
• To determine whether your pan is hot enough for the oil, do a simple water test: drop a tiny amount of water (about 1/8 teaspoon) into the pan. When the water immediately forms a ball that glides across the surface, your pan is preheated perfectly.

If you are unable to prevent heat tarnish on your stainless steel pans, you can always remove the discolouration by cleaning your pans with vinegar. Simply dilute some white vinegar with water, scrub with a non-abrasive sponge, and then rinse and dry your cookware.

What other types of stains can occur on stainless steel pans

Stainless steel is an alloy of iron, chromium, and other metals that vary depending on the type of stainless steel. Chromium, which must comprise at least 10.5% of the mixture for it to be considered stainless steel, protects the iron from rusting. While stainless steel is designed to resist corrosion and rust, it can still be stained by heat tarnish, as well as other types of stains. Here are some other common types of stains that can occur on stainless steel pans:

Food Stains

Food can leave stains on stainless steel pans if left for long periods or soaked in water overnight. Food scraps, especially those containing salt or acids, can cause dullness and discolouration on stainless steel. To remove food stains, it is recommended to use a mixture of dish soap and warm water, scrubbing in the direction of the grain. For stubborn food stains, a paste of baking soda and dish soap can be used, or a commercial cleaner such as Bar Keepers Friend.

Chemical Stains

Stainless steel is susceptible to corrosion and staining caused by certain chemicals, including bleach and oven cleaner. Cleaning stainless steel with harsh chemicals can damage the protective layer of chromium oxide, leaving the steel susceptible to further corrosion. Never use steel wool or abrasive cleaning pads, as they can scratch the surface and make it more vulnerable to staining. Instead, use a microfiber cloth or soft brush to clean your stainless steel pans.

Water Spots and Stains

Hard water can leave white, cloudy residue or water spots on stainless steel pans. To prevent water spots, it is important to dry your cookware immediately after washing. To remove hard water stains, a mixture of vinegar and water can be boiled in the pan, which will help to break down the chalky buildup.

Rust Stains

While chromium in stainless steel helps to prevent rusting, stainless steel can still be susceptible to rust stains, especially if exposed to salt or left in contact with cast iron or silverware with salty food scraps. To remove rust stains, scrub the surface with a paste of water and baking soda, or use a bleach-free scrub powder like Bar Keepers Friend or Zud, which contain oxalic acid to help remove the compromised chromium oxide layer.

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