How To Clean Black Residue Off Cast Iron Skillet

Three ways to clean black residue off cast iron skillets are:

  • Self Cleaning Oven
  • Soap & salt mixture
  • Vinegar & baking soda

The reason these methods work so well are as follows:

Self cleaning ovens use extreme temperatures to breakdown black residue or burnt food into an ash like substance that’s extremely easy to wipe off.

Soap is a degreaser which softens the black residue followed by a salt scrub where the salt acts as the abrasive.

Vinegar is an acid that breaks down anything alkaline and since most black residue is from charred food or oils, these are alkaline which allow the vinegar to act aggressively on them.

Just make sure that it is black residue and not an incorrectly seasoned pan which leads to your cast iron being sticky after seasoning.

How To Remove Black Residue Off Cast Iron Skillets

There are a few methods when it comes to cleaning black residue off a cast iron skillet. Personally I prefer to use a self cleaning oven first, and then move onto the more traditional methods to do a final clean.

Below are all the methods I use to clean black residue off my cast iron skillet.

Self Cleaning Oven

This method I love for cleaning cast iron cookware, because self cleaning ovens reach a temperature of around 500 degrees Celsius, and cast iron cookware can tolerate that kind of heat.

Self cleaning ovens work by using extremely high temperatures that oils, food residue and carbon residue cannot withstand and they breakdown.

To clean the black residue on cast iron skillets using this method, simply place the cast iron skillet upside down in the oven, turn the self cleaning cycle on, and leave it until the cycle has finished.

This should normally take a few hours.

Dish Soap & Kosher Salt

Using soap and salt to clean cast iron pans is a traditional method, the soap acts as a degreaser, and the salt is the abrasive.

Start by adding dishwashing soap to the cast iron skillet and use a sponge to scrub it all over. While that’s taking effect and breaking up the black residue, fill half a cup with salt.

After 10 minutes, pour the salt into the cast iron skillet and start scrubbing with the sponge. This should remove any black residue on your cast iron pan.

Once you feel like all the black residue on the cast iron pan is gone, rinse it thoroughly with some warm water, scrub with the sponge if needed. You want to clean any of the cleaning mixture off.

Now dry with some paper towels, you need to remove all the moisture by doing this as cast iron rusts very easily.

Finally, just to be safe, heat the cast iron skillet on the stovetop to evaporate any left over moisture.

Vinegar & Baking Soda

Vinegar is amazing for cleaning, especially cleaning black residue off cast iron skillets. It’s high acidity can break down even the strongest of bonds since residue is mostly alkaline and acid breaks down anything alkaline.

To use this method, simply pour some vinegar into your cast iron skillet and boil the vinegar. Once the vinegar has boiled, add some baking powder. You should see a reaction occur.

Let the vinegar and baking soda mixture cool down, and start to scrub away at the black residue. This should clean it straight off.

Now rinse the cast iron skillet under some warm water, and again place it back on the stovetop to evaporate any moisture left over to prevent your cast iron pan from rusting.

What is the black coating on a cast iron skillet?

Black residue is normally the seasoning on a cast iron pan. The seasoning reacts to the iron to create a visible black layer of seasoning.

Other causes can be down to burnt food simply building up in the pan and over time creating a layer of burnt on food.

Is black residue on a cast iron pan harmful?

Over time, black residue will always build up in your cast iron pan due to seasoning and burnt food. This is unavoidable.

The black residue from seasoning is completely harmless, and it shouldn’t come off into your food anyway as it’s bonded against the cast iron cookware.

If the black residue is from burnt on food, then it’s perfectly safe to cook in and is very unlikely to increase your risk of cancer. However it will add a charred taste to your food and ruin the flavor, so it’s best to keep your pan clean from any burnt food.

How To Prevent Black Residue

Preventing a build up of black residue will not only save you time and effort, but it will protect your cast iron cookware.

Since black residue is mainly due to carbonized/polymerized oils and burnt food, it’s quite easy to avoid.

Keep it clean – Cast iron pans tend to get very hot, and this causes food and greases to burn onto the bottom of the pan. This is mainly what causes black residue. Ensure you are cleaning your pan with warm water after every use.

Reseason – If you have started getting a small build up, simply clean the current layer of seasoning off and re-season it. This will prevent a large build up of black residue, saving you both time and effort in the future.

How To Season A Cast Iron Skillet

After cleaning off black residue on cast iron skillets, you will most likely need to add seasoning back onto it, this is because during the cleaning process you will have taken off the current layer of seasoning.

Simply follow the steps below to re-season your cast iron skillet.

  1. Add some sort of cooking oil like flaxseed oil, olive oil, vegetable oil or canola oil to your cast iron pan.
  2. Use a paper towel to smear it around the surface ensuring the entire pan is coated in oil.
  3. Preheat your oven to the smoke point temperature of the oil
  4. Place your cast iron pan upside down in the oven and bake it for 1 hour.
  5. Repeat the above process 3 times to ensure a built up layer of seasoning.

How To Prevent Rust On Cast Iron Skillets

Sometimes rust can have a black tint to it and look like black residue. However all rust is brown/orange and if you discover that your black residue is rust, you need to clean it off straight away.

Rust will keep on eating away at your pan, until eventually it becomes unusable. It forms when the water, oxygen and iron react together so to prevent it from building up, you need to ensure your cookware is dry after every wash.

You also need to make sure that you are not storing it in a place with lots of moisture. The best place to store cast iron is in a dry dark place such as a cupboard.

To clean rust off, you simply needs to use some steel wool and warm water. Simply add the warm water to the pan and start scrubbing away with the steel wool ensuring that your getting all of the rust off, especially on the cooking surface.