There are several signs of a poorly seasoned cast iron skillet. Fortunately, they are easy to repair, no matter how dire the situation may seem. That’s an added bonus to owning and cooking with cast iron. The signs of a poorly seasoned cast iron skillet are: foods sticking to the surface, a sticky surface, flaking, rust, bad odors, and black residue.
Before we get into the issues and the repair methods let’s review what seasoning on a cast iron means. A properly maintained cast iron will have a deep black, semigloss look to it and the surface will be non-stick. This seasoning happens when cast iron is cleaned and oil is rubbed unto the surface and then heated up for a minimal amount of time.
When oil is heated in cast iron long enough, the fatty acids oxidize into a plastic-like coating.. The cast iron is porous so it allows the oil to bake in and form a non-stick coating. Low saturated oils are best to use as they polymerize better. The more you use and season your cast iron, the more non-stick it will become.
1. Food Sticking To The Surface
Food sticking to a cast iron skillet means one of three things. The first one is that the skillet wasn’t seasoned well enough to form several layers of non-stick. The other reason for food sticking is because the food was heated too long and the food scorched. The food is essentially burned onto the bottom of the skillet. The last cause of food sticking to a cast iron skillet is because not enough oil or fat was used in the cooking process and the food burned onto the dry surface of the skillet.
2. Sticky Surface
If a cast iron skillet has a sticky surface this usually means that there is an excess of oil built up on the surface. This can happen for a variety of reasons. The wrong oil was used, the oil wasn’t heated up to the correct temperature, the oil wasn’t heated long enough, or the heating surface used to heat up the oil wasn’t hot enough. In these instances, the oil never got the chance to polymerize with the cast iron.
Flaking occurs when the seasoning breaks down and the temperature of the skillet chips the seasoning off. Generally, this occurs on the side of the skillet because oil dripped down the side during the seasoning process. If flaking occurs on the cooking surface of the skillet, excess oil has built up in the cast iron’s pores and broke off when the skillet got hot. Flaking is unsightly but not harmful although it will show up in your food.
Rust occurs when a cast iron is exposed to too much moisture. Remember, a cast iron skillet is metal and, like all metals, cast iron rusts when it isn’t properly dried off or it is left in a moist environment for too long. If a cast iron skillet is left in a sink to soak, placed in a dishwasher, or stored near a dishwasher, rust occurs. Although rust is not harmful, you shouldn’t cook in rusty cast iron pans. See these tips for keeping your cast iron skillet rust-free.
Off-putting odors occur when fish or other pungent food is cooked in a cast iron skillet and the skillet is not cleaned properly. Cast iron can also get a rancid metallic odor from the seasoning breaking down. Generally, bad odors occur when a cast iron isn’t washed properly and too much oil is left on the surface.
6. Black Residue
A black residue on a cast iron is a sign of your seasoning coming off. The black residue is carbon deposits that form when oil or fat is overheated or from leftover food bits. Low smoke point oils carbonize at high temperatures so it is good to research oil smoke points before cooking with them, especially with cast iron. However, the black residue is not harmful and usually shows up when you are cooking with liquids.
How To Fix a Poorly Seasoned Cast Iron Skillet
Fixing a poorly seasoned cast iron skillet is easy and there are a few options to choose from. The first methods, the stovetop method, and the oven method, are for minor damage such as stickiness or not enough seasoning. The scouring methods are for more severe damage such as rust or stuck on food. Then, there is a simple method to remove unwanted odors from the cast iron skillet.
The first option for minor repairs is the stovetop method. Heat the cast iron skillet on the stovetop and dip a paper towel in 2 tablespoons of oil. Hold the paper towel with a pair of tongs and wipe the surface of the skillet until it becomes dark with a semigloss sheen. Make sure the skillet is not sticky. Repeat the method 3-5 times until the cast iron skillet is seasoned properly.
The second option for minor repairs is the oven method. Preheat the oven to 500 ℉. Wipe the surface of the skillet with 1 tablespoon of oil. Remove any excess oil with a clean paper towel. The skillet should look dry. When the oven is preheated, place the skillet upside down on the center rack and bake for one hour. Remove the skillet using potholders and allow it to completely cool before using it.
To remove stuck-on food from the skillet you can scrape the food off with a wooden or plastic spatula. After the food comes off, make sure to reseason the skillet, especially the areas where the food was stuck on. If this method is not working, pour water into the skillet, just enough to cover the bottom of the skillet and heat on the stovetop on high. Once the water is boiling, scrape the stuck-on food off with a wooden or plastic spatula.
Once the food is removed, dry thoroughly with a paper towel and reseason the skillet. If you have to add water to cast iron, it is best to season the piece in the oven to ensure the entire skillet dries. If it doesn’t dry all the way, rust will occur.
To repair a sticky cast iron skillet, add a tablespoon of oil to the skillet prior to cooking with it. After the food is cooked, remove any food bits with a wooden or plastic spatula and reseason the cast iron with a tablespoon of oil. Make sure to wipe all the areas of the skillet and season it in the oven or on the stovetop.
To eliminate flaking caused by carbon deposits, scour the skillet lightly with a scouring pad and season it by adding one tablespoon of oil to the skillet. Wipe the oil over the entire surface and place it on the stovetop or reseason it in the oven for one hour.
For rust, scour the skillet with warm soapy water and a scouring pad. It is okay to add water to the skillet during this process because it will be completely reseasoned at the end of the process. You can also use a spatula to remove rust. The trick is to scrub the skillet lightly so you don’t damage the cast iron. Once the rust is removed, apply a thin layer of oil to the skillet and bake, upside down in the oven at 500 ℉ for one hour.
To eliminate unwanted odors from a cast iron skillet, bake the skillet in the oven at 500 ℉ for 15 minutes. This simple method is effective and it won’t damage the seasoning on the cast iron. The other, more traditional method, is to pour salt in the skillet and let it set overnight. Then, rinse the salt off and dry the skillet thoroughly and reseason it.
Another simple trick is to boil water in the skillet until the odors dissolve. For stubborn odors, you can also add a baking soda mixture consisting of five parts water to one part baking soda. This method is very effective and should solve the odor issue. Whatever method you use, other than the baking method, make sure to reseason the skillet before using it again.
If odors persist, the cast iron will have to be scoured and reseaoned. What this does is remove the seasoning completely. Essentially, you will be starting from scratch. It is recommended to try the above-listed methods a couple of times before this is done, especially if the cast iron is well seasoned.
There are several ways to remove black residue from a cast iron skillet. The easiest method is to ignore the residue and continue to cook in the skillet. The residue will gradually go away the more the cast iron is used. To remove black residue instantly, there are two ways to go about this: salt and water.
For the salt method, boil one or two cups of water in the skillet. The hot water will loosen the carbon deposits. Allow it to simmer for a couple of minutes and discard the water. Then, add one cup of salt to the skillet and wipe the skillet with a dish towel. The abrasive salt will lift the carbon deposits away from the skillet. The salt will change color as it absorbs the deposits. Dry the skillet thoroughly and reseason.
The water method is straightforward. Boil one or two cups of water and scrub the dark spots with water. As the water becomes dirty, discard the water and repeat until the deposits are gone. This method isn’t as effective as the salt method but some people prefer it over the abrasiveness of the salt. Once the deposits are gone, dry and reseason the skillet by baking.
My name is Jason Phillips and I cooked for many years, primarily aboard Merchant Marine vessels and in fast-paced commercial kitchens. My passion for culinary arts led me to attend a culinary arts academy in 2019 where the instructor piqued my interest in food and beverage writing.